Dramatic sexuality changes after brain disturbance:
The Neurocritic has compiled a collection of interesting neurological studies where a number of patients seems to have experienced a profound change in their sexual preferences as a result of brain disturbance.
One of the most well-known of these studies is a recent case of a man who was convicted of paedophilia late in life, but was later found to have a brain tumour, and on removal of the tumour his sudden interest in children disappeared. It reappeared again when the tumour once more began to grow.
The case has raised questions about free will and self-determination in light of the fact that such morally reprehensible acts seemed only to occur when a tumour was affecting brain function.
It's importantly to mention that brain damage rarely causes such tragic events, although sexual difficulties, in general, are not uncommon. Problems can range from difficulties with arousal and enjoyment, to behavioural disturbances and inappropriate behaviour.
In some rare cases, preferences themselves seem to be affected, although it's never clear whether it's actually that the person has different desires, or whether they always had them but now are, perhaps, less able to stop themselves acting on them.
It's easier to think that damage has changed people's desires when the behaviour markedly unusual, such as this case of a man who was, to put it bluntly, screwing the coin return tray of a public telephone after brain deterioration.
But one thing we know from the forensic literature and cases of healthy people who accidentally die during sexual practices (for example, thesetwo), is that no matter how strange the attraction seems to you, someone is out there expressing it.
Not all of the cases of changes sexuality after brain damage are where people act outside of the norm, of course. In one, admittedly, not brilliantly detailed case, an apparently exclusively homosexual man found he developed heterosexual attraction after a stroke.
Sadly, this area is massively under-researched so we really know relatively little about how different aspects of desire, emotional attachment and sexual behaviour are handled by the brain, but these case studies give us a window into the possibilities.
Link to The Neurocritic on 'Unusual Changes in Sexuality'.
I've just discovered a curious medical finding that can be detected on MRI brain scans called the 'face of the giant panda sign' where, quite literally, it looks like there's a panda face in the middle of the brain, indicating a specific pattern of neural damage.
The image you can see on the left is the 'face of the giant panda sign' that appeared in a brain scan of a patient with multiple sclerosis who started showing unusual sexual behaviour and is taken from a 2002 study. Click the image if you want to see the whole scan.
The pattern is apparently caused by "high signal in the tegmentum, normal signals in the red nuclei and lateral portion of the pars reticulata of the substantia nigra, and hypointensity of the superior colliculus".
It is most associated with Wilson's disease, a genetic condition which causes a toxic build-up of copper in the body, but obviously can appear in other disorders as well.
Technology Review has a fantastic photo essay that tracks how we've visualised the brain from times past and includes some of the most stunning images from the last century of neuroscience.
It's been put together by Mo Costandi, the writer you may know from the Neurophilosophyblog, with each image concisely described so you can get an insight into exactly what you're seeing.
Link to 'Time Travel Through the Brain' photo essay.
BBC News has a fascinating short video report of a robotic hand that is connected to the nerve fibres of an amputated arm and which allows the patient to actually feel touches with the robot fingers.
Although it doesn't mention it in the report, the technology is from the SmartHand research group who are attempting to use knowledge about the cognitive neuroscience of action and body sensation to make fully integrated naturally controlled prosthetics.
There's an interesting part of the video where the patient says "When I grab something tightly I can feel it in the finger tips, which is strange because I don't have them anymore".
In other words, despite the fact that the robot hand feeds touch information into the nerve fibres into the arm stump, the patient feels the sensations 'in' the robot fingers.
This is essentially the 'rubber hand illusion' and the same research group demonstrated exactly this in a recent experiment where they induced touch sensations in a robot hand by stroking it and the stump simultaneously.
This is interesting because a recent study found that sensations in people with intact arms only transferred to a realistic looking rubber hand and not a wooden one, whereas this research team uses a obviously false robot limb.
The fact that touches transfer to an obviously false hand for someone with an amputation but not for people with intact limbs is interesting, because it suggests that brain's remaining body-image 'maps' for the amputated hand may be being recruited to enhance the illusion.
Link to BBC News video report "New robotic hand 'can feel'". Link to SmartHand project.
The latest edition of the Journal of Neuroscience has a fantastic collection of articles by leading neuroscientists who look back on the last 40 years of discoveries in brain research.
The collection is to celebrate the 40th anniversary of the Society for Neuroscience. As the articles make clear, the last four decades have seen a huge expansion in our knowledge of how the brain works and the Society asked leading lights in the field to reflect on this scientific revolution.
Memory and Brain Systems: 1969–2009 by Larry R. Squire [link]
Neurotransmitters, Receptors, and Second Messengers Galore in 40 Years by Solomon H. Snyder [link]
Four Decades of Neurodegenerative Disease Research: How Far We Have Come! by Anne B. Young [link]
A Paradigm Shift in Functional Brain Imaging by Marcus E. Raichle [link]
The Development of Developmental Neuroscience by Carol Mason [link]
The Biology of Memory: A Forty-Year Perspective by Eric R. Kandel [link]
Strictly speaking, they're not all retrospectives. For example, while Larry Squire gives a whistle-stop tour through the last 40 years of the cognitive neuroscience of memory (and you'll probably not read a better brief article in this area), Marcus Raichle takes the opportunity to look forward and is clearly enthusiastic about the 'default network' which he is co-credited with discovering.
They're all academic articles, so are not the most accessible if you're not familiar with the scientific literature, but as brief guides to some of the major areas of neuroscience they're fantastic and freely available online.
Science News has a brilliant special issue on the 'science of slumber' that tackles sleep disorders, the mental impact of sleep deprivation, how sleep differs across species and the still mysterious question of why we need to sleep.
I found the article on two seemingly straightforward sleep disorders, insomnia and narcolepsy, the most interesting. They seem straightforward because they appear as a lack and an excess of sleep, but as the piece makes clear, they are still quite mysterious.
Insomnia is particularly interesting because having trouble sleeping happens to everyone at some point, so in itself, it's not abnormal - meaning that research into what triggers it is unlikely to find anything striking.
Instead research has shifted to try and understand what prevents insomnia from resolving naturally so it becomes a chronic condition:
Sleeplessness may be brought on by traumatic events such as a death in the family, an illness such as cancer or anything else distressing, causing a person to lie awake at night with a racing mind. For a subset of people, though, insomnia has no prompting signal — a condition called primary insomnia.
Regardless of the trigger (or lack thereof), temporary insomnia has a nasty way of becoming a habit. Poor sleep habits can become ingrained. When trouble sleeping persists for three or four nights a week over several months, insomnia is considered chronic.
It may turn out that untangling the prompting signals of insomnia, as many sleep researchers attempt, is a fool’s errand, says Michael Perlis, director of the University of Pennsylvania’s Behavioral Sleep Medicine Program in Philadelphia. “The whole zeitgeist has changed,” he says. Most sleep researchers now agree that “once insomnia goes chronic, it stays that way,” regardless of the prompting signal, Perlis says. So rather than focusing on the immediate trigger for insomnia, many scientists are trying to figure out why it becomes chronic and how to prevent that from happening.
I also liked the short piece that briefly compares the amount of type of sleep between lots of different animals. It seems dolphins don't have REM sleep. I wonder if that means that they lack or have very limited dreams?
Anyway, a great collection of articles and all freely available online.
There's a curious case published in the medical journal Epilepsy and Behavior of a young man who had his epilepsy triggered by the sight of stairs. This would cause seizures that would trigger "repetitive hugging and affectionate kissing of one of the people around him".
Our patient is currently 24 years old. He is a right-handed male with a history of right temporal lobe epilepsy. He had his first seizure when he was 10 years old. His seizures usually started with an aura of a “feeling” inside his body or abdomen. This feeling, described at times as pain or nausea, lasted a few seconds or a few minutes. His eyes would then widen, he would become confused, and he would look around right and left as if wondering. The seizure would last 1 to 2 minutes with altered consciousness, spitting, and often repetitive hugging and affectionate kissing of one of the people around him.
At times this was followed by head and eye deviation to the left and, sometimes, rotation of the whole body to the left side. Occasionally, he would walk around for a few seconds. These seizures were often precipitated by looking at stairs, whether or not he was walking up the stairs. He learned to avoid looking at stairs to avoid having seizures. He also noted that looking down a flight of stairs did not precipitate his seizures.
I am constantly amazed by both how seizures can be triggered by very specific experiences (such as seeing a certain thing, or hearing a specific sound) and how they can lead to very selective actions.
This is by no means a typical effect of epilepsy but it does raise the interesting question of how these very narrow experiences lead to destabilising brain states which trigger a seizure.
I have heard anecdotal reports from several clinicians that they've met patients who can 'think their way out' of a seizure by deliberately focusing their thoughts on a specific topic, presumably which reduces the destabilising effect of their original 'trigger experience'.
I've not seen this discussed in the medical literature though, so if you know of any articles that do tackle it, I'd love to hear about them.
Link to PubMed entry for stair triggered epilepsy case.
Electrical readings from seven patients who died in hospital suggest that the brain undergoes a surge of activity at the moment of death, according to a study just published in the Journal of Palliative Medicine.
Palliative care is a medical approach that aims to make dying patients as comfortable as possible. As part of this, doctors from George Washington University Medical Centre's intensive care unit were using standard alertnessmonitors for seven patients that include EEG measurements of the frontal lobes.
The monitors are commercial devices designed to help anaesthetists monitor how 'awake' patients are, and they combine the electrical readings from the brain into a single signal that reflects alertness.
For each of the seven patients, the researchers noticed that at the point where blood pressure dropped to zero there was a surge in brain activity. The graph on the right is from one of the patients and shows a typical activity burst.
This is not the first time these have been noticed, but previous reports were single cases and the electrical surges were explained away as due to electrical interference from other sources. In these new cases, the doctors could be pretty confident that previously suggested sources of interference weren't present.
Instead, they suggest that the surge was due to 'anoxic depolarisation' - a process where the lack of oxygen destabilises the electrical balance of the neurons leading to one last cascade of activity.
Now, this is just a case series and the neuroelectrical measures aren't the best. The researchers encourage more systematic research with appropriate tools, but they do suggest an intriguing hypothesis with regard to 'near death experiences':
We speculate that in those patients who suffer cardiac arrest who are successfully revived, they may recall the images and memories triggered by this cascade. We offer this as a potential explanation for the clarity in which many patients have "out of body experiences" when successfully revived from a near death event.
One of the difficulties, of course, is that although 'near death experiences' are a well-known phenomenon, we only know about them from people who weren't really dying (or even from people who were never actually 'near death' as one of my favourite studies attests).
Nevertheless, neuroscience studies on the dying are likely to be of increasing interest especially as the debate about what counts as death become more prominent.
I just found a curious case study of a man who developed 'robotic speech' after being hit by lightning. Rather than the "I am a Dalek!" style mechanical sound it seems to be more like the very. deliberate. and. exact. speech synthesis style, somewhat like Data from Star Trek the Next Generation
Lightning-induced robotic speech
Neurology. 1994 May;44(5):991-2.
To the Editor
Because of a recently observed case, I was intrigued by the communication of Cherington et al[1] concerning lightning encephalopathy. The authors referred to evidence by Critchley[2] that the cerebellum can be selectively injured in lightning-struck patients, Two of their there patients had signs of cerebellar dysfunction. MRI in one of their patients evidenced superior cerebellar atrophy.
The force of a lightning strike threw a 20-year-old roofer to the ground from the truck in which he was standing. Panicked, he immediately began to run. A numbness and weakness of his arms and back cleared after several days, but the more striking abnormality was a profound alteration of his speech, which he described as having become robotic. Each syllable was clearly enunciated with a slight pause between syllables, so that while the flow of his speech was slowed, he was able to communicate well. His speech was actually easier to comprehend than that of some normal persons. His brother had indeed complained that the patient's premorbid speech had been too rapid and word-jumbled; that speech was transformed to robotic speech, with fine diction and super-clear enunciation. Each morning, his speech was "normal" until shortly after he began to talk, when it reverted to the robotic pattern for the remainder of the day. The neurologic examination was normal except for right upper extremity hypalgesia. Brain MRI was normal.
I considered his robotic-speech problem to be most like the "scanning speech" of cerebellar disease. I have found no references to similar cases, but the reports of selective cerebellar injury by lightning strike[1-3] lead-me to suspect that robotic speech maybe a more common sequel than has been recognized.
Gordan J. Gilbeft, MD
St. Petersbutg, FL
1. Cherington M, Yarnell P, Hallmark D. MRI in lightning encephalopathy. Neurology 1993; 43(7):1437-8
2. Critchley M. Neurological effects of lightning and electricity. Lancet 1934;1:68–72
3. Morocutti C, Spadaro M, Amabile G. TRH treatment in cerebellar ataxia following a lighting stroke. Ital J Neurol Sci 1989;10:531.
The original authors reply and seemed somewhat baffled, saying that it could equally arise from the shock of the experience rather than damage to the brain.
The New York Times has an absolutely fantastic article on the psychology and neuroscience of anxiety and how an anxious temperament at birth can ebb and flow during our lifetime.
It's an in-depth article that really does justice to the topic, looking at extensive research into our anxious states, but also carefully questioning some of the sloppy assumptions of many article where brain activity is described as directly representing mental states.
But having all the earmarks of anxiety in the brain does not always translate into a subjective experience of anxiety. “The brain state does not make it a disorder,” Kagan told me. “The brain state exists, and the statement ‘I’m anxious,’ exists, and the correlation is imperfect.” Two people can experience the same level of anxiety, he said, but one who has interesting work to distract her from the jittery feelings might do fine, while another who has just lost his job spends all day at home fretting and might be quicker to reach a point where the thrum becomes overwhelming. It’s all in the context, the interpretation, the ability to divert your attention from the knot in your gut.
The article is incredibly well written and it tackles a huge range of topics in the understanding of fear and anxiety. Highly recommended.
Link to NYT article 'Understanding the Anxious Mind' (via @mocost)
I've just found this remarkable TV interview with Oliver Sacks from 1986, only a year after the publication of his famous bookA Man Who Mistook His Wife for a Hat.
It's a fascinating discussion, not least because it's something you don't see much these days - an extended interview that focuses solely on a neuroscientist and his work.
There are no gimmicks or attempts to jazz it up with fancy editing and graphics. We see everything during the discussion, including Sacks' many 'ums' and 'ahs' and even hear a telephone going off half way through!
Still, it's a really wide ranging discussion which covers everything from the effects of brain injury to the role of doctors in exploring their patients' lives.
From what I can make out, the interviewer is Harold Channer who did the piece for a Manhattan-based public access TV network probably before Sacks became well-known.
The video quality is a bit ropey but Sacks has a spectacular beard and is as chaotically engaging as ever. Classic stuff.
I've just found a brief but interesting study finding that migraines are much more common in neurologists than the general public which inspired an interesting reply by Oliver Sacks.
The prevalence of migraine in neurologists
Neurology. 2003 Nov 11;61(9):1271-2.
Evans RW, Lipton RB, Silberstein SD.
To assess the prevalence of migraine among neurologists and neurologist headache specialists, the authors performed a survey of neurologists who attended a headache review course. The 1-year and lifetime prevalences of migraine in the 220 respondents were as follows: male neurologists, 34.7%, 46.6%; male headache specialists, 59.3%, 71.9%; female neurologists, 58.1%, 62.8%; and female headache specialists, 74.1%, 81.5%. Migraine is much more prevalent among neurologists than in the general population.
Sacks later wrote to the journal to mention an earlier study finding much higher levels of migraine-related visual disturbances in doctors than other people. He also wonders:
Speculating on the possible reasons for the prevalence of migraine in neurologists, and particularly headache specialists, Evans et al. wonder, among other possibilities, whether "a personal history of migraines might stimulate an interest in neurology and headache as a subspecialty." For myself, with a personal history of classical migraines (and, more often, isolated visual ones) going back to childhood, the extraordinary phenomena of the aura (which for me included transient or partial achromatopsia, akinetopsia, as well as visual agnosias, alexias, etc), excited an interest in the brain, and especially in visual processing, at an early age. These migraines were certainly one of the reasons I was attracted to neurology, why I chose migraine as the subject of my first book, and why I devoted a large part of this book to illustrating the varied presentations of visual auras in my patients
However, he gets short shrift from the researchers who curtly point out that their survey asked whether neurologists' experience of migraine had influenced their career choice and they said no, so it can't be true.
This is clearly not the finest psychological reasoning in the world and I remain fascinated by whether personal experience shapes the specialisation of clinicians.
It only happens in some cases of course. It's probably rare that neurologists had their interest sparked after major brain damage or oncologists after experiencing cancer.
We do know, however, that psychiatrists are morelikely to have experienced mental illness than other doctors and I wonder how many other links between clinical speciality and illness experience there might be.
Neurosurgical Focus has an excellent article on the development of stereotactic neurosurgery where an external frame is usually screwed into the skull and fixes the head in place to allow surgeons to precisely locate brain areas in a standard 3D space.
In modern stereotactic surgery, the system is usually used with an electronic tracking system that maps the surgeon's instruments onto a previously acquired brain scan in real-time. The frame allows the brain scan and the actual brain to be precisely aligned.
This means the surgeon can, for example, place a depth electrode into a precise spot without having to physically see that area while still being confident that they're in the right place.
The system is also used in research labs to ensure that, for instance, the brain is stimulated in precisely the right spot with magnetic pulses, using a technology called transcranial magnetic stimulation or TMS.
For example, if researchers wanted to see the effect of stimulating the auditory cortex they could run a listening experiment in an fMRI machine, see exactly where your auditory cortex is by mapping the activity on your brain scan, and then use a stereotactic system (e.g. this one) to guide the TMS machine to exactly this spot on your actual brain.
With all of its high-tech trappings, I never realised that the first human stereotactic system was created in 1918 with the system you can see in the picture.
The Neurosurgical Focus article looks at how the technology has developed from the original brass contraptions to the modern age of neurosurgery.
Link to Neurosurgical Focus on the history of stereotactic brain surgery.
I've just found this alarming case study [pdf] from the Singapore Medical Journal about a patient who had a nail banged into their head by a local healer in an attempt to treat persistent headaches.
Craniocerebral penetrating wounds caused by nails are rare and reported as curious experiences. A 45-year-old female patient presented with a metal nail in situ in the middle of her head, very close to the right side of the midline. The patient had been unconscious since the time of injury. There was no history of vomiting or seizures. Neurologically, the eye opening and verbal response were nil, but she was localised to the pain and moved all four limbs equally. The pupils were bilaterally symmetrical and reactive to light. General and systemic examinations were unremarkable.
The relatives revealed that she had been suffering from a headache (more on the right side) for the last ten years, with off and on exacerbation. They took the patient to a Tantrik, who hammered the nail into her head to get rid of the bad omen. Anteroposterior and lateral radiographs of the skull showed a foreign object inside the skull, very near to the midline. As there were no facilities to perform computed tomography (CT) in the peripheral hospital, the nail was removed under local anaesthesia, based on the radiographical findings. After the removal of the nail, she was managed conservatively and made a gradual recovery in her sensorium. The patient was doing well at follow-up.
As medical historian Owsei Temkin discussed in his definitive book on the history of epilepsy The Falling Sickness (ISBN 0801848490) banging nails into the head was also a Roman 'treatment' for seizures.
Link to PubMed entry for case study. pdf of full text of case study.
I just found a curious article from the Journal of the American Medical Association about a case of 'laugh syncope' - a condition where the patient passes out when they crack up with laughter.
Syncope is the medical term for when someone feints and it is caused by a reduction of oxygen to the brain.
At 4 PM on a March day, a 32-year-old, previously healthy barber was standing and cutting a client’s hair. The client related a funny story, upon which the barber broke out into a very strong, sustained, loud, and unrestrained laughing fit during which, according to observers, he "blacked out" and fell to the floor. Although he sustained interscapular bruising and minor trauma to the right shoulder, he exhibited no seizure activity and no bladder or bowel incontinence.
He regained consciousness within a few seconds, was completely oriented, had no apparent neurological deficit, and immediately resumed his work. He had been working on his feet throughout the day, but this was customary for him and he had never had a syncopal or near-syncopal episode before. The temperature at the time had been mild. The timing of his most recent meal was not recorded. The patient did not reveal the content of the story.
I love that last sentence. It reminds me of an earlier medical warning about the dangers of powerful jokes.
I note there's another case of 'laugh syncope' that was published last year.
Apparently these cases can be caused simply by problems with getting the blood to the brain (such as heart difficulties), problems with the brain itself (for example, difficulties with its own blood supply network or the occurrence of a seizure) or due to what is known as a vasovagal episode that can be due to psychological triggers or vagus nerve dysfunction.
Link to 'Shear hilarity leading to laugh syncope in a healthy man'.
I've just had pick my jaw up from the floor after reading an article on the brain scanning of unborn babies. I was idly wondering whether anyone had attempted to do an MRI scan of the fetal brain only to find that researchers are so advanced that they can do almost any sort of adult neuroimaging on the fetus - including psychological studies of brain activation.
One of the main difficulties with brain scanning unborn babies is that they move about a lot. You can asks adults and children to stay still, but fetuses are a little bit harder. One of the major advances in the field has been the development of algorithms to reconstruct high definition scans from blurred images.
Researchers have also completed diffusion scans that can create 3D maps of the white matter 'cabling' of the brain in the unborn baby, as with a recent study [pdf] on how brain connections develop during gestation. Recent studies have similarly been able to measure developing brain metabolism and examine how the size and shape of specific areas change during pregnancy.
But most amazingly, several studies have conducted functional MRI experiments on fetuses. In other words, they measured neural activity in specific brain areas in response to specific experiences.
The two scans on the right are from a 2008 study that looked at whether unborn babies at the 33rd week of development would show brain responses to sound in their auditory cortex, part of the temporal lobes. The researchers simply put headphones on the belly of the pregnant women and scanned while they played tones.
The top scan is from an adult, while the one from the bottom is from one of the fetuses, showing clear and selective activity the auditory cortex nearest the sound source.
I was completely blown away by that, and researchers are continuing to develop new and intriguing ways of presenting experiences to the fetus (such as shining lights through the belly to look for visual brain responses!).
Link to PubMed entry for paper on brain scanning fetuses.
The Llullaillaco mummies are the spectacularly preserved bodies of three sacrificial children from a 500-year-old Inca civilisation found at more than 6,500m above sea level in the Peruvian Andes. I've just found a study that brain scanned the mummies and the results are nothing short of stunning.
I've tried to link each scan to the picture of the relevant mummy (although I have to say, the online photos of the mummies are a bit inconsistently labelled so I apologise for any mismatching) and you can see how remarkably well-preserved they are both inside and out.
The mummies are of a 15-year-old girl, a 7-year-old boy and a 6 year-old girl that are thought to have been left as part of a ritual Inca sacrifice. From the article:
The scientific excavation was carried out at an altitude of 6,739 m above sea level on the summit of Mount Llullaillaco in the northwestern Argentinean Andes at an average temperature of –15°C. These children had been sacrificed 500 years ago in times of the Inca Empire to appease the mountain deities and to ensure the emperor's well-being. In addition, the mummies were buried with more than 100 objects, including textiles, gold and silver statues, pottery, and feathered headdresses.
The children had been buried in three pit tombs built by the Incas by enlarging natural niches in the bedrock at the summit shrine of Mount Llullaillaco, which is considered to be the highest archaeological site in the world. The mummies were individually buried 1.7 m deep with their associated offerings. The funerary sites were covered with a mixture of soil and stones, which was also used to fill in the platform that was later built to cover the burials.
According to a National Geographicnews story, the older girl was found to have chewed coca leaves and drunk corn liquor, the latter possibly to put her asleep.
Link to study on brain scans of Llullaillaco mummies. Link to NatGeo story on the mummy of the older girl.
Gizmodo has picked up on an interesting new neurosurgery simulator that not only provides virtual reality skills training but also allows doctors to use data from MRI scans to practice on the brain of a specific patient.
The system also gives tactile feedback through the instruments, so you can feel the resistance in the brain tissue as you 'cut' through it.
According to a piece in TechReview, it's the result of an ongoing project to create a neurosurgery simulator that started last year in Canada.
Check the Gizmodo page for a news clip where you can see the simulator in action.
Link to Gizmodo with video of NeuroTouch. Link to TechReview write-up.
Instant reflex may reveal brain injury after knock out:
I've just found a fascinating video clip reporting on newly discovered reflex action that occurs after a knockout blow. The researchers scoured YouTube for videos of nasty bangs the head and found many examples of the reflex appearing in people as they hit the deck.
The news clip is a a bit American (Americans, if you're not sure what this means, to us, all your news seems like this) but includes some video clips which illustrate the response in sportsmen who have been knocked out.
The researchers who have discovered the response have named it the 'fencing response' apparently because it looks like the en gard position in fencing - presumably though, only if you've never actually seen any fencing.
It actually looks more like the boxing stance with both hands out in front with elbows bent.
They suggest in their study that the response is a visible marker of moderate brain injury.
Link to news clip on the 'fencing response'. Link to abstract of study.
Your gut has its own neural network. Called the enteric nervous system, it controls digestion and has as many neurons as the spinal cord.
Parkinson's disease is a brain disorder that has been long associated with stomach upsets. These were often explained away as due to poor diet or stress, but it seems increasingly likely that the disease may also be affecting the neurons in the digestive system.
It was originally thought just to destroy dopamine neurons in a deep brain structure called the nigrostriatal pathway, an effect which causes the distinctive movement problems, but it has become clear that the disorder causes damage throughout the nervous system via the formation of protein clumps called Lewy bodies.
A new article in European Journal of Neuroscience suggests that Parkinson disease affects the enteric nervous system, which might tie together some curious findings in the medical literature that have remained unexplained for many years.
Stomach upsets, swallowing and digestion problems have long been associated with Parkinson's but it has never really been clear why.
While we commonly think of it purely in mechanical terms, digestion is remarkably complex process and the enteric nervous system is involved in the careful regulation of the muscle ripples of the gut, secretion of digestive fluids and blood flow to aid absorption.
Damage to this system would cause exactly the sorts of problems that have been reported in Parkinson's disease patients and this fits with some previous findings that have been ignored for many years.
Until recently, only one study had investigated whether the enteric nervous system was damaged in Parkinson's patients. It found that large numbers of the gut's dopamine neurons seemed to be missing in patients with the disorder.
The next study appeared more than ten years later, this time looking for protein clumps in the gut of deceased patients, and found evidence that not only were these tell-tale signs present, but that the distribution suggested that neurons in the gut may be the first to be damaged.
The author of this study, neuroscientist Heiko Braak now proposes the radical idea that while we know part of the risk for Parkinson's is genetic, maybe an environmental trigger - a virus - could get into the nervous system via the stomach, eventually triggering the brain changes that lead to the debilitating tremors and movement problems.
Link to Parkinson's and gut nervous system article summary.
Discover Magazine has an excellent Carl Zimmer article on glial cells. They make up the majority of the brain's volume but they get relatively little attention from the neuroscience community who would rather focus on the seemingly more lively neurons.
There's a traditional format for these stories, that says that we used to think that glial cells were just 'scaffolding' for the brain that gave protected padding for the neurons, but now we are on the verge of a breakthrough in understanding what they do.
Here's one from New Scientist in 1994, and a pdf of another from Scientific American in 2004.
One difficulty has been integrating the action of glial cells into the popular cognitive model of the brain that suggests that it works as an information processing device.
While there have been various discoveries about the biological function of glia, this is the first article I've read which gives a clear idea of how one type of glial cell, the astrocyte, might be involved in information processing.
For some brain scientists, these discoveries are puzzle pieces that are slowly fitting together into an exciting new picture of the brain. Piece one: Astrocytes can sense incoming signals. Piece two: They can respond with calcium waves. Piece three: They can produce outputs—neurotransmitters and perhaps even calcium waves that spread to other astrocytes. In other words, they have at least some of the requirements for processing information the way neurons do. Alfonso Araque, a neuroscientist at the Cajal Institute in Spain, and his colleagues make a case for a fourth piece. They find that two different stimulus signals can produce two different patterns of calcium waves (that is, two different responses) in an astrocyte. When they gave astrocytes both signals at once, the waves they produced in the cells was not just the sum of the two patterns. Instead, the astrocytes produced an entirely new pattern in response. That’s what neurons—and computers, for that matter—do.
If astrocytes really do process information, that would be a major addition to the brain’s computing power. After all, there are many more astrocytes in the brain than there are neurons. Perhaps, some scientists have speculated, astrocytes carry out their own computing. Instead of the digital code of voltage spikes that neurons use, astrocytes may act more like an analog network, encoding information in slowly rising and falling waves of calcium. In his new book, The Root of Thought, neuroscientist Andrew Koob suggests that conversations among astrocytes may be responsible for “our creative and imaginative existence as human beings.”
Obviously this is based on the idea that we need to fit new biological findings into the computational model, rather than fitting our model of the mind into the biology, but that's a whole different battle.
Link to Discover article 'The Dark Matter of the Human Brain'.
The Wellcome Trust is putting its archive of medical films online which includes some fascinating footage of some 1933 neurosurgery to remove a tumour from the frontal lobe.
The film says the tumour is a tuberculoma. While we typically link tumours to cancer, the name also refers to other types of abnormal growths.
In this case, it's an abnormal growth caused when tuberculosis (TB) reaches the brain and leads to an infected mass that can have a similar effect - damaging the cortex by taking up space where the brain should be.
Because TB can be treated effectively with antibiotics, tuberculomas are now very rare in the West, but they are still unfortunately quite common in parts of the developing world where access to medical care is limited.
The Wellcome archive footage is from a time where TB was much more common and shows how surgeons of the days would have removed the mass and how the patient is left after recovery.
Link to Wellcome archive footage of 1933 brain surgery.
Today's Nature has a fantastic article about how psychoactive drugs are being developed into a new generation of chemical weapons design to have specific psychological effects on the enemy.
This has long been part of military research (see the famous and unintentionally hilarious footage of British troops being given LSD presumably from the 1950s) but the effects of the mind altering weapons have generally been thought to be too unpredictable and largely restricted to the lab.
However, the Nature article argues that as our knowledge increases and specific biochemical pathways in the body are discovered, chemical and biological weapons are likely to be deployed that target highly selective biological mechanisms to incapacitate and disable.
Some researchers are actively facilitating the development of new chemical weapons. For example, a research group from Pennsylvania State University in University Park has identified several drug classes as potential non-lethal agents or 'calmatives', including benzodiazepines and alpha2-adrenoreceptor agonists, as well as individual drugs such as diazepam and dexmedetomidine...
Those who support the development of incapacitating agents often argue that using them in conflict situations stops people being killed. Historical evidence suggests otherwise. At the Nord-Ost [Moscow theatre] siege, for instance, terrorists exposed to the fentanyl mixture were shot dead rather than arrested. Likewise, in Vietnam, the US military used vast quantities of CS gas — a 'non-lethal' riot-control agent — to increase the effectiveness of conventional weapons by flushing the Viet Cong out of their hiding places.
The piece notes that the current international laws on chemical and biological weapons do not address this form of armament which are typically marketed under the 'non-lethal weaponry' banner.
From past experience, including the fact that the fentanyl-based 'incapacitating' gas seemed to have killed the majority of people during the Moscow theatre siege, it is likely that they will be used in anything but a non-lethal manner.
Link to Nature 'Biologists napping while work militarized'.
There's a curious historical snippet in the latest edition of Neurology about how the famous French neurologist Jean-Martin Charcot designed a shaking chair for patients with Parkinson's disease after they reported sleeping better after a train or carriage ride.
The most obvious symptom of Parkinson's disease is tremor and name first given to the condition, by James Parkinson in his famous essay, was the 'shaking palsy'.
While Charcot's 19th century contemporaries had tried 'vibration therapy' here and there, he was the first to systematically apply it to patients with Parkinson's and found it helped with stiffness, discomfort and poor sleep.
Later Gilles de la Tourette, a one-time student of Charcot, developed the treatment into a type of electrical vibrating hat to specifically apply a 600 rpm treatment 'directly' to the brain.
The treatment was seemingly forgotten for many years but recently it has been revived and studies have found modestbenefits for vibration therapy in Parkinson's disease.
One of the mysteries of the human brain concerns why the surface is wrinkled into 'ridges' and 'trenches'. We covered some of the theories a couple of weeks ago but a new study in the Journal of Biomechanics suggests a completely different take - the rippled surface protects against the effects of head injury.
The research team created a 3D computer model of the brain taken from an MRI brain scan (top) and then generated a second model (bottom) but with the sulci (the 'trenches') smoothed out.
They then took each model and simulated a few smacks upside the head from different directions. As well as 'striking' the head head on, the researchers also simulated blows causing 'rotation'.
This is where the brain moves as if it is pivoting around a point. For example, if you look straight on and loll your head from side to side, your brain is following the path of a 'coronal rotation'. These sorts of blows are known to be a particular cause of tears in the white matter, your brain's 'cabling'.
It turns out that a brain with sulci on the surface suffers significantly less strain when the head is struck. And this isn't just for areas near the surface.
The sulci also had a protective effect almost everywhere, including deep brain structures like the brain stem and the corpus callosum.
So it seems that having a wrinkly brain may be a good protective measure for when your head has to bounce off a hard surface.
Link to paper 'Can sulci protect the brain from traumatic injury?' Link to PubMed entry for same.
The Boston Globe has a short but interesting article on cerebral folding - the science of why the brain is wrinkled up like a damp walnut.
The wrinkled surface of the brain folds into 'ridges' known as gyri and the 'trenches' known as sulci. This rippled landscape forms perhaps the most recognisable aspect of the human brain but we still don't really know why we need this rather odd arrangement.
The standard answer "to fit more brain surface in the skull" really tells us nothing on its own as it's not clear why the same material in the outer brain layers couldn't be distributed differently.
Some answers are starting to emerge, however, not least from studies which look at differences in brain folding during the pre-birth growth phase and between people with different neurological conditions.
The article is full of fascinating findings from this research, not least of which is that the brain is smooth until quite late in pregnancy and only starts to fold in the last few months of development.
Premature babies seem to have this process partially disturbed for reasons that aren't yet clear:
For example, because so much of the folding takes place during the latter weeks of fetal development, premature infants arrive with much of their cortical development yet to be completed. And the folding patterns of preemies relegated to the neonatal intensive care unit don’t match those of their counterparts who spend their full nine months in the womb. New research from Van Essen’s lab shows that even when preemies reach their originally forecasted due dates, their brains are not as large or as folded as those of full-term newborns.
“That means there’s something different in how those brains are organized and in the connections that have formed,’’ Grant said. Perhaps some extra environmental influence in the hospital is disrupting folding or preemies are missing out on some vital influence that their counterparts get in the uterus, though researchers haven’t yet narrowed down what these influences may be.
The article is brief but is packed full of eye-opening discoveries on brain folding. It's one of those areas were we know so little but what we do know is quite compelling.
Link to Globe article 'Unfolding the mysteries of the brain'.
According to pressreports Michael Jackson will be buried without his brain because it is still 'hardening'. Although this may seem unusual, the 'hardening' process is actually a standard part of any post-mortem examination where the brain is thought to be important in the cause of death, such as in suspected overdose.
It involves removing the brain from the skull and leaving it to soak in a diluted mixture of formaldehyde and water called formalin. This soaking process usually takes four weeks and the brain genuinely does harden.
A 'fresh' brain is a pinkish colour and has the consistency of jelly, gello or soft tofu meaning it is difficult to examine and the various internal structures are often hard to make out.
After soaking the brain, it has the consistency and colour of canned mushrooms making it easier to slice, examine and photograph. However, because the brain is so soft to start with, it can't just be dropped in a tank of fixing solution, because it will deform under its own weight.
To solve the problem it is usually suspended upside down in a large bucket of formalin by a piece of string which is tied to the basilar artery.
After it has 'hardened' or 'fixed' it is sliced to look for clear damage to either the tissue or the arteries. Small sections can also be kept to examine under the microscope.
Because this part of the post-mortem takes several weeks preparation it is usually only carried out with the family's permission as the body may need to be buried without it, or the burial delayed until the procedure is finished.
This also means that this form of post-mortem brain examination is usually only carried out where there is a feeling that examining the brain can help clarify the cause of death - which is what pathologists are often most concerned with.
In cases such as Michael Jackson's, where the effects of drugs are suspected to play a part, pathologists will be looking for evidence of both sudden-onset and long-term brain damage. If they find it, they'll be trying to work out how much it could have been caused by drug use and how much it contributed to the death.
Over the last couple of days, there's been a great deal of coverage of threenewstudies on the genetics of schizophrenia. While the coverage has actually been pretty good, almost all the news stories make the same error when talking about the 'genetic risk' for the condition.
Twenty years ago, geneticists were searching for the 'gene for schizophrenia' until it became apparent that there was not going to be a single gene, or even a handful, found responsible for the mental illness.
It since became a mantra that the genetic risk for schizophrenia would be conferred by 'many genes of small effect'. In other words, the cumulative effect of lots of genes that, on their own, would be quite benign.
Nature has just published three studies that use the only-recently-feasible technique of scanning the whole genome and has reported the first convincing positive evidence for the 'many genes of small effect' theory by finding that a whole bunch of genes, when considered together, account for about a third of the total difference in schizophrenia risk.
Interestingly, all three studies find that many of the genes lie in a region called the 'major histocompatibility complex' - a series of genes involved in the function of the immune system.
However, lots of the newsreports, even from science publications give variations on the theme that 'genetic factors account for 80 percent of the total risk of getting schizophrenia'.
This 80% figure (which can vary, some give 90%) is not an estimate of risk and shows a misunderstanding of estimated heritability taken from twin studies.
Luckily, I tackled exactly this issue in a column for July's edition of The Psychologist:
Nature versus nurture is a lie. Music is not melody versus rhythm, wine is not grapes versus alcohol and we are not environment versus genes. We are their sum, their product and their expression. They dance together and we are their performance, but neither is an adversary. The art of understanding this elegant ballet is complex and arcane but you may never realise this from reading the quoted results of genetic studies, because the extent to which a trait is heritable, that is, accounted for by genetics, is usually expressed as a simple percentage.
If you search Google for the phrase “80 percent genetic”, you will discover hundreds of sources that claim that everything from schizophrenia, to height, to intelligence has been found to be four fifths ‘genetic’. Pick any other figure and you can find everyone from psychologists, to politicians, to journalists claiming that this or that is explained by genes to a given percentage. Geneticists know the subtly of this percentage and why these statements, usually lifted from the results of twin studies, are misleading, but clearly many others do not.
Imagine a mental illness is described as being 80% heritable. This is often taken to mean that four fifths of an individual’s risk is down to his or her genes, but this is not the case. What it means is that 80% of the variance in the measured illness was explained by genetic factors in the specific group that was studied. If this seems like a frivolous distinction, bear with me, because it is key in understanding heritability and it becomes crystal clear when tackled as an example.
Imagine that we could study a population where everybody lived in an identical environment. They did the same things everyday; they ate identical foods, had identical relationships and were stressed by identical events. Their lives were carbon copies of each other. A twin study would find that mental illness would be close to 100% heritable, because if the environment is fixed, any difference must be down to genetics. In fact, twin studies would find that everything is close to 100% heritable, for exactly the same reason. To flip our thought experiment on its head, if we only studied genetically identical clones, everything would be 0% heritable, because any difference must be down to the environment.
These figures do not necessarily tell us anything about the potential for a trait to be influenced by nature or nurture, because heritability is rarely an immutable and absolute fact about biology; it is an overall measure of how things are for that group, at that moment. In other words, the process of measuring the influence of genetics is, itself, subject to environmental factors. It captures the dance, not the dancers.
Thanks to Jon Sutton, editor of The Psychologist who has kindly agreed for me to publish my column on Mind Hacks as long as I include the following text:
"The Psychologist is sent free to all members of the British Psychological Society (you can join here), or you can subscribe as a non-member by emailing sarsta[at]bps.org.uk"
Link onetwothree to Nature genetics of schizophrenia studies. Link to good write up from Science News, despite 80% genetic risk slip-up.
A 64 year old woman developed a phantom third arm after a stroke, but unusually, the patient was able to see and feel the illusory limb. A study just published online in the journal Annals of Neurology used brain scans to examine the patient. They established that the phantom sensations were accompanied by similar sorts of brain activity as you'd get from a real arm.
Unlike a classic 'phantom limb', where a patient feels sensations as if they're coming from the previously amputated body part, a 'supernumerary phantom limb' is where a phantom seems to appear additional to the already existing arm or leg.
The condition is rare but has been reported before and is known as the 'supernumerary phantom limb' in the medical literature. As we discussed last year, it is usually associated with strokes that affect the subcortical areas of the brain.
One of the reasons this new case is so interesting is because not only could the patient feel their additional limb, but they claimed to be able to see it and feel touches from it as well.
Tactile sensations in the SPL [supernumerary phantom limb] happened when she clenched her hand (she could then feel her phantom palm with her phantom fingers) and when she “touched” certain parts of her body (in which case, the sensation was felt both in the phantom and the touched body part).
She could touch parts of her head, as well as her right shoulder. She claimed to be able to use the SPL to scratch an itch on her head (with an actual sense of relief). Moreover, she reported that the phantom could not penetrate solid obstacles (see supplementary materials for more details).
While a handful of cases of 'visible' supernumerary phantom limbs have been reported, this combination of seeing and feeling the touch of one is unique.
Importantly, the patient was not delusional - they didn't believe they had an extra limb - they knew the sensations were unrealistic, but the experience was still there.
The limb was also not permanently felt - the patient could trigger it at will - and it appeared "pale," "milk-white," and "transparent."
The researchers were keen to see if these sensations were reflected in the activity of the brain by using fMRI scans.
They found that 'moving' the phantom limb in front of the line of sight caused increased activation in the visual cortex of the brain.
Most strikingly, they found that when asked to 'touch' her cheek with the illusory hand, activity in brain areas representing cheek sensation increased.
There is always the chance that someone with very bizarre symptoms could be lying, but it is also the case that brain disturbance can cause all sort of confusions and distortions - so in some cases a patient's description of what's happening may not always be a reliable guide to exactly what they're experiencing.
In this case, the brain imaging suggests that the 'supernumerary phantom limb' was genuinely being perceived as a visible additional arm and that its 'touches' were being processed by the sensory system in a similar way to touches from existing limbs.
Because the condition is so rare, and so conceptually bizarre, there is no good explanation of why it occurs except that it may be linked to the disturbance of our already established body and action 'maps' in the brain.
Apparently, there is more information about the case in supplementary material which can be found 'in the online version of this article', but the additional information doesn't seem to be online. Ironically, the study seems to have a phantom of its own.
Newsweek has a short but smart essay by neuroscientist Eric Kandel who riffs on some of the latest developments that have pushed forward our understanding of the neurobiology of mental disorder.
Kandel gives a description of one of the big biological discoveries from recent years, namely copy number variations, and explores what they might tell us about the development of psychiatric disorders:
One major advance has been the discovery that there is much more variability in the genome than had been anticipated, and that this takes the form of copy number variation (CNV). These are duplications or deletions of segments of a chromosome, often involving several or tens of genes, that enhance or depress the actions of specific genes. A well-known example of a CNV is the extra copy of chromosome 21 resulting in Down syndrome. It has recently been discovered that this type of variation is extremely common in everyone's genome.
As he goes on to explain, CNVs have caused a lot of excitement in the world of mental illness research, not least because they've been found to occur in 'out of the blue' cases of schizophrenia - people without a family history of the disorder - suggesting that the disorder could be partially explained in some people by DNA 'lesions'.
Some rare CNVs have been found to greatly increase the risk for schizophrenia, but unfortunately they don't help explain the genetics of schizophrenia in general because there are many people with schizophrenia who don't have these rare CNVs.
Nevertheless, this rare CNV finding may help us understand the neurobiology of the disorder by giving us clues based on how these unusual copy variations affect brain growth and protein expression.
Interestingly, those CNVs which have been found to increase the risk of schizophrenia also increase the risk for other disorders such as autism and intellectual disability (what the Americans call 'mental retardation') - suggesting that our diagnostic divisions between disorders may not be well supported by genetics.
Despite the title of the article, Kandel also highlights recent developments in psychotherapy, which have given us far the biggest advance in effective treatments for mental disorders in recent years.
Newsweek seem to have just released a whole collection of articles on biomedical sciences of which Kandel's contribution is a part. But don't miss a good article on 'how science will enhance your brain' and another piece on epigenetics.
Look on the right hand side for links to all the articles in the series.
Link to Newsweek on 'A Biology of Mental Disorder'. Link to Newsweek on 'How Science Will Enhance Your Brain'. Link to Newsweek piece on epigenetics.
The straight dopamine theory could be up in smoke:
There is now growing evidence that cannabis use causes a small but reliable increase in the chance of developing psychosis. Traditionally, this was explained by the drug increasing dopamine levels in the brain but a new study shortly to be published in NeuroImage suggests that the active ingredient in cannabis doesn't effect this important neurotransmitter.
Despite some dissenting voices, disruption to the mesolimbic dopamine pathway is widely thought to be the key problem in the development of delusions, hallucinations and the other psychotic symptoms commonly diagnosed as schizophrenia.
This has led to the assumption that the small increased risk of psychosis reliably associated with cannabis use is due to the drug increasing dopamine levels in a deep brain structure called the striatum.
In itself, this is partly based on another assumption - the virtual mantra of recreational drug research that 'all drugs of abuse increase dopamine levels in the reward system' of which the striatum is a part.
This new study, led by neuroscientist Paul Stokes, tested dopamine levels by using a type of PET brain scan where participants are injected with a radioactive tracer that binds to free dopamine receptors. Higher dopamine levels will mean that there are less free dopamine receptors and, therefore, lower tracer levels.
Participants were tested twice, once when given placebo and once when given a dose of pure THC - one of the most important active ingredients in cannabis. The dose was designed to be roughly equivalent to the amount you might absorb from a single joint.
The researchers found no difference in dopamine levels between the THC and the sugar pill, even though the participants clearly reported the effects of the drug.
Although they only tested 13 participants, this is the largest study of its kind so far. These type of neurotransmitter tracer studies are know to produce conflicting results at times, so further experiments will be needed to be sure of the result.
But if it is the case that cannabis does not cause a significant increase in dopamine levels, this will mean our ideas about cannabis and psychosis will need a rethink.
It also shakes up the idea common idea that all recreational drugs are pleasurable because they affect the 'dopamine reward system'.
Forbes magazine has an excellent special issue that is rammed full of diverse and interesting articles on artificial intelligence.
It's a large collection of short articles that covers everything from the mathematics of free will to the likelihood of there being a robot war in the future (see, it's not just me).
There are a fair few speculative pieces, so those who like their transhumanists with a pinch of salt may have to be ready with the seasoning, but wide variety of articles means there should be something for everyone.
Each intends to introduce an idea rather than explore it in detail. I liked the pieces on whether AI can help fight terrorism and another on how the use of AI to explore theories of the mind has declined, and I'm still reading through the rest.
The only slight annoyance is that the series starts with the cliché question "Can machines think?"
Perhaps the single most sensible response I ever read to this was a quote from a speech but the much missed Dutch computer scientist Edsger Dijkstra:
"The question of whether machines can think... is about as relevant as the question of whether submarines can swim."
I've just found this remarkable case study of a woman with an unpredictable form of 'alien hand syndrome' that was triggered when she had a seizure.
The syndrome, where you lose conscious control of one of your hands while it carries out unbidden actions, is normally associated with permanent damage to the brain, often in the frontal lobes, but this version only occurred when an epileptic seizure was in progress.
A 65-year-old right-handed Cuban woman experienced her first seizure while driving. She described an initial tonic posturing of her left foot with march throughout the leg.
This was followed by a counterclockwise truncal contortion and repetitive clonic movements of the foot, followed by her left hand viciously slapping her face, “as if it was fighting with me.”
Subsequent seizure semiology [presentation] has been similar, although her nondominant left hand has refined its movements as to pretend it is applying lipstick.
Because of the embarrassing smearing of her preferred loud cherry-red lipstick, the patient has been forced to use more natural colors.
A new study has surveyed 17 astronauts to see what sort of headaches they experienced while on space missions. Headaches were much more frequent than on earth and didn't fit a known type, suggesting that zero or micro gravity may be a specific trigger for a pounding head.
Below is the part of the article where the researchers discuss how the weightless conditions of space might affect the brain to cause the headache.
To describe headache, most astronauts used terms such as 'exploding' and/or 'a heavy feeling', confirming previous observations and suggesting a change in intracranial pressure. This is compatible with headache attributed to disorders of homeostasis, which can change during a state of microgravity. Certain haemodynamic [blood flow] changes might explain the occurrence of space headache. Alteration of cerebral blood flow and volume have been shown during exposure to microgravity.
The most striking change is the cephalad fluid shift, when body fluid redistributes and the blood volume in the upper body increases. The fluid shift towards the brain and probable brain oedema [swelling] could lead to an increase in intracranial pressure. Insofar as microgravity is also known to induce hypoxia [reduced oxygen supply to brain tissue], it also might be considered as a plausible trigger for space headache
Link to article. Link to PubMed entry for same. Link to write-up from BBC News.
I've just discovered there's a form of neurotoxic honey, genuinely known as "mad honey", created by bees taking nectar from the beautiful rhododendron ponticum flower, pictured on the right.
The nectar from these plants, prevalent around the Black Sea region of Turkey, occasionally contains grayanotoxins, a class of neurotoxin that interferes with the action potential (electrical signalling) of nerve cells by blocking sodium channels in the cell membranes. This leads to problems with the muscles, peripheral nerves, and the central nervous system.
Mad honey apparently causes "a sharp burning sensation in the throat" and poisoning leads to dizziness, weakness, excessive sweating, hypersalivation, nausea, vomiting and 'pins and needles' although severe intoxication can cause dangerous heart problems.
Luckily, most cases aren't fatal and resolve after 24 hours.
Mad honey was known to the Romans, and was specifically discussed by Pliny the Elder.
Link to brief review article on mad honey. Link to PubMed entry for same.
New Scientist has a tantalising snippet reporting on a shortly to be released and potentially important new study challenging the idea of 'mirror neurons'.
Mirror neurons fire both when we perform an action and when we see someone else doing it. The theory is that by simulating action even when watching an act, the neurons allow us to recognise and understand other people's actions and intentions...
However, Alfonso Caramazza at Harvard University and colleagues say their research suggests this theory is flawed.
Neurons that encounter repeated stimulus reduce their successive response, a process called adaptation. If mirror neurons existed in the activated part of the brain, reasoned Caramazza, adaptation should be triggered by both observation and performance.
To test the theory, his team asked 12 volunteers to watch videos of hand gestures and, when instructed, to mimic the action. However, fMRI scans of the participants' brains showed that the neurons only adapted when gestures were observed then enacted, but not the other way around.
Caramazza says the finding overturns the core theory of mirror neurons that activation is a precursor to recognition and understanding of an action. If after executing an act, "you need to activate the same neurons to recognise the act, then those neurons should have adapted," he says.
The study is to appear in the Proceedings of the National Academy of Sciences and apparently is embargoed so the full text is not yet available, although it should appear here when it is.
The announcement is interesting because using adaptation is a novel way of testing 'mirror neurons' and the lead researcher, Alfonso Caramazza, is known for a long series of influential neuropsychology studies.
He has a reputation for being a sober and considered scientist so it will be interesting to see if the final study is really the challenge to mirror neurons as it seems.
Although the hype has subsided a little, the years following the initial reports saw these now famous neurons being used to explain everything from language, to empathy, to why we love art.
We're now in a period where we're taking, if you'll excuse the pun, a somewhat more reflective look at the topic and developing more nuanced theories about how this brain system functions.
UPDATE: Grabbed from the comments. Looks like this paper might have the potential to cause a ruckus. A comment from mirror neuron researcher Marco Iacoboni:
Caramazza’s paper is seriously flawed. The technique of fMRI adaptation seemed very promising ten years ago, but careful studies on its neurophysiological correlates have demonstrated that its findings are uninterpretable. Indeed, Caramazza’s manuscript has been around for many years and nobody wanted to publish it. Caramazza managed to publish with an old trick that only PNAS allows: he handed it personally to a friend of his. The paper is basically unrefereed (this is what it means ‘Edited by...’ under its title).
Link to NewSci on 'Role of mirror neurons may need a rethink'.
NPR has an interesting audio series on brain function, spiritual experience and the growing field of neurotheology. It's takes a fairly broad brush approach and has audio, video, an interactive thingy, and plenty of supporting material.
You might get slightly annoyed at some of the section titles ('The God Chemical', 'The God Spot') but there are some great little audio vignettes in there where people describe their spiritual experiences, whether they've been caused by prayer or even psilocybin - the main active ingredient in magic mushrooms.
The project borders on the edge of being a bit hokey at times but it saved by the commentary and interviews with neuroscientists working in the area.
There's also a good article in June's Scientific American entitled 'Why People Believe Invisible Agents Control the World' which looks at the origin of belief in angels, demons, spirits and the like.
Link to NPR interactive brain / god thingy. Link to 'Why People Believe Invisible Agents Control the World'.
Bolt from the blue triggers bizzare hallucinations:
I just found this amazing case study of a female mountaineer who was struck by lighting while climbing the Latemar Peak in the Alps and subsequently experienced a series of unusual symptoms.
She was taken off the mountain by helicopter and was so agitated in hospital she had to be put under for three days. On wakening she was having some remarkably bizarre hallucinations.
On 3 September 2004, a 23-year-old healthy woman was hit by a "bolt from the blue" while climbing on a ridge at 2750 m shortly before reaching the Latemar Peak in the Alps from a southern direction. The accompanying climber was about 50 m from the casualty, and reported that at the time of the incident (about 15:00 Central European Time (CET)), the sky was clear and sunny. He heard cracking thunder and was thrown to the ground by a massive shock wave.
The patient was also thrown to the ground, lost consciousness for a few seconds and was confused afterwards. She had no vision, dazzled by a bright light. On arrival of the air rescue team, her Glasgow Coma Scale was 9. She was hospitalised and because of extreme agitation, set to a drug-induced coma for 3 days. The initial CT scan showed bilateral occipital oedema, but no intracerebral or subarachnoid haemorrhages or skull fractures...
In the evening, still awake and 6 h after extubation, strange phenomena occurred. These exclusively visual sensations consisted of unknown people, animals and objects acting in different scenes, like a movie. None of the persons or scenes was familiar to her and she was severely frightened by their occurrence. For example, an old lady was sitting on a ribbed radiator, then becoming thinner and thinner, and finally vanishing through the slots of the radiator.
Later, on her left side a cowboy riding on a horse came from the distance. As he approached her, he tried to shoot her, making her feel defenceless because she could not move or shout for help. In another scene, two male doctors, one fair and one dark haired, and a woman, all with strange metal glasses and unnatural brownish-red faces, were tanning in front of a sunbed, then having sexual intercourse and afterwards trying to draw blood from her.
These formed hallucinations, partially with delusional character, were in the whole visual field and constantly present for approximately 20 h. At the time of appearance, the patient was not sure whether they were real or unreal, but did not report them for fear that she might be considered insane.
Frontal Cortex has alerted me to an interesting NPRradio segment on the fact that taller people have longer nerves and so will have slight sensory lag in comparison to shorter people.
It prompted me to look up some of the research in the area and I found an eye-opening study looking at a range of factors that can effect nerve conduction.
The researchers found that, after controlling for sex, age and temperature (it turns out your nerves are quicker when you're warm), there was a 0.27 m/s decrease in the conduction speed of one of the leg nerves (the sural nerve) for each additional centimetre in height.
This is interesting because it is not only a reduction in time because the same speed signal is travelling a longer distance, but it actually seems that nerve signals travel more slower through longer nerves as well, owing to the fact the nerves get thinner the longer they are.
The radio segment suggests that taller people don't experience the world as any different, because our brains try to make everything seem 'in sync'.
In fact, this is a problem for everyone, no matter how tall we are, because we know we can update our actions quicker than the sensory signals can reach the brain.
In one of the most popular theories that attempt to explain this it it thought that we have an internal simulation of our actions that we can use to make fast decisions which is updated as and when sensory information arrives.
However, I tried to find some studies on whether taller people actually have slower reaction times, but I couldn't find any, so let me know if you do.
Link to NPR 'The Secret Advantage Of Being Short'. Link to study on nerve conduction factors. Link to DOI entry for same.
I've just read an elegant study on the neuroscience of gambling that wonderfully illustrates why the dopamine equals pleasure myth, so often thrown around by the media, is too tired to be useful.
I have seen countless news reports that claim that some activity or other causes dopamine to be released; that dopamine is the 'pleasure chemical'; and that it's also released by 'drugs', 'sex', 'gambling' and 'chocolate' (a quartet I have named the four dopamen of the neurocalypse).
Normally, this breathless attempt to make something sound sexy is followed by a slightly sinister bit where they say that this dopamine activity is also likely to make it 'addictive'.
Dopamine is involved in drug addiction, but the over-extended cliché is drivel, not least because the dopamine neurons start firing in the nucleus accumbens when any reward is expected. Whether it be heroin, a glass of water when you're thirsty, or your favourite book on calculus - if that's what floats your boat.
And herein lies the subtlety. Our best evidence tells us that while the dopamine system has many functions, it's not really a reward system - it's most likely a reward expectancy system of some kind. Theories of exactly what form this takes differ in the details, but it certainly seems to be active when we're expecting a reward, whether it actually turns up or not.
The study on gambling, led by neuroscientist Luke Clark, demonstrates that this is true even when the actual experience is unpleasant.
The research team looked at the activity differences in the dopamine-rich mesolimbic system in a gambling task - comparing wins, misses and near-misses. Near-misses were where the reels on a slot machine just missed the payout.
It turns out that near-misses activate almost exactly the same dopamine circuits as actual wins - but here's the punchline - they were subjectively experienced as the most unpleasant outcome, even worse than total misses.
In other words, the dopamine system was firing like a rocket display but the experience was awful.
Interestingly, although near-misses were experienced as aversive they increased the desire to play the game but only when the person had some perception of control, by choosing what the 'lucky' picture would be.
Of course, like choosing 'heads or tails', it's only an illusion of control because the outcome is random anyway.
But because of reward expectancy the dopamine system is most active when we think we can control the outcome and modify our strategy next time, even if that sense of control is completely false.
Link to full-text of study on near-misses and dopamine. Link to good coverage of study from Quirks and Quarks.
I've just found a video of someone with alien hand syndrome - a condition which usually occurs after brain injury or stroke where the affected person loses conscious control over the hand and where it seems to move with a will of its own.
In this case, the video was uploaded by YouTube user frankenerin, who asked someone to video her when she was in intensive care after suffering a stroke and having brain surgery while her 'alien hand' was still present.
There's a couple of things to notice in the video. The first is that the clinician asks the patient to do the actions for using scissors and brushing teeth. This is to check the problem is not a form of general ideomotor apraxia, where common action patterns are damaged.
She can do the actions with one hand but not the other, suggesting her strange movements are not due to global action planning problems.
The clinician then asks whether the patient recognises the arm as hers.
This may seem an odd question, but he's checking for somatoparaphrenia, where patients can deny ownership of a paralysed or action-impaired limb, sometimes saying that it belongs to someone else.
As it turns out, the patient says she generally knows it is hers, but when it is draped across her body in a certain position and making involuntary movements she can think it is someone else's limb. In other words, she seems to have fleeting somatoparaphrenia.
The video then shows the hand moving of its own accord and the patient having to use the other hand to keep it out of trouble.
Despite looking like she's in pretty bad shape, frankenerin later posted a wonderful follow-up video where she is back on her feet and feeling fine, although discusses how she's had to adjust her career aspirations owing to the longer-term effects of the brain injury.
Unfortunately, the Wikipedia page on alien hand syndrome, also known as anarchic hand syndrome, is dreadful, but there's an excellent 2005 article from The Psychologist by neuropsychologist Sergio Della Sala that covers the neuropsychology of the condition and what it tells us about free will. You can read it online as a pdf.
Link to alien hand syndrome video. pdf of The Psychologist on alien / anarchic hand.
A new article from Trends in Cognitive Sciences explores how cognitive neuroscientists are becoming increasingly interested in understanding hypnosis and are using it to simulate unusual states of consciousness in the lab.
Hypnosis was typically treated with suspicion by mainstream cognitive science, although an important turning point came when a 2000 study demonstrated that people hypnotised to see colour on grey panels showed activity in the colour perception areas of the brain.
Myths about hypnosis are still common, but it is nothing more than a participant's willing engagement in a process of suggestion. The hypnotic induction, sterotypically the counting backwards and the 'you are feeling sleepy' patter, helps but is not necessary.
Crucially, and for reasons that are still unclear, we all vary in our hypnotisability. This characteristic is known to be more stable than IQ, and normally distributed, like many other psychological traits.
In other words, we can all experience the relaxation and focus, and we can all imagine what the 'hypnotist' is suggesting, but only more highly hypnotisable people experience the suggestions as involuntary, as if they're happening 'by themselves'.
Recent research has suggested that highly hypnotisable people can disengage the process that looks out for rival demands on our attention, from the process that allows us to focus on which of the competing tasks we need to home in on.
In other words, in highly hypnotisable people, suggestions to experience things contrary to everyday reality may be able to take effect because the normal detect and disentangle mechanism has been temporarily suspended.
Combined with carefully crafted suggestions, this ability allows researchers to simulate certain mental states and experiences in the lab.
For example, hypnotically suggested paralysis, blindness or loss of feeling have been used to simulate the symptoms of 'hysteria' or conversion disorder, a condition where neurological symptoms appear without any damage to the nervous system being present.
Other studies have used hypnosis to simulate the feeling that the body is being controlled by outside forces, a common symptom in psychosis, or where a patient thinks their reflection in the mirror is another person, a delusion called mirror misidentification.
And we covered a fantastic study last year, where researchers used hypnosis to simulated psychogenic amnesia, a loss of memory just for old information despite the fact that the patients have none of the brain damage associated with the classic amnesia syndrome.
This new in-depth article covers research attempting to understand hypnosis itself, and science that uses hypnosis as a lab tool, and is a great introduction to the neuroscience research in this developing area.
In the long history of outrageous drinking stories, this has got to be one of the best.
The Emergency Medical Journal has a case study of a man who woke up in hospital after being admitted for alcohol poisoning. He couldn't remember what happened the night before but when his hangover didn't clear a precautionary brain scan revealed a knife blade embedded in his temporal lobe.
A left handed, 22 year old man was brought to the hospital by friends at 0200 because of alcohol intoxication. Events preceding the admission and motivation for the patient to go to the hospital were unclear. The patient's relatives confessed to a binge drinking of rum and beer, and then being moved suddenly, probably to avoid police control...
The patient woke up 8 hours after admission, complaining of severe headache covering the whole head and gradually increasing in intensity... Surprisingly, brain computed tomography revealed a right temporal haematoma 34 mm in diameter, with a knife blade that had entered from the temporal fossa and was deeply retained in the right temporal lobe (fig 1).
The foreign body was surgically withdrawn, and postoperative recovery was uneventful. After awakening from surgery, the patient could not remember involvement in an altercation, but witnesses retrospectively confirmed that he was attacked with a knife after drinking with his assailant.
There's also a lovely sentence in the paper which has an apt typo: "Vigorous stimulations only induced growling and repelling movements of the harms and legs".
Link to 'an unusual cause for headache following massive alcohol intake'.
I've just found an article with two interesting cases of 'exploding head syndrome' - a medical condition where affected people spontaneously hear an exceptionally loud explosion-like noise.
The condition is relatively harmless, causing people only to be startled, and it doesn't seem linked to seizure activity or epilepsy. Owing to the fact it's both benign and uncommon, it's not been widely studied and so its cause remains a mystery.
Case 1
A 48-year-old man was seen in December 2006. For the past several months about three to four times a month, he had been having attacks of a peculiar sensation in the head likened to the noise of an exploding bomb only at night while going off to sleep. The 'explosion' would wake him up and disappear completely the moment he woke up.
There was no headache and no associated symptoms such as nausea, vomiting or any visual sensation. For the past 3 months, the frequency of these sensations had increased and had been occurring nearly daily at the time of consultation. The noise occurred only once during every night, after which he could go off to sleep. His past medical history had been unremarkable and he had never suffered from any significant headache problem. General physical and neurological examination had been unremarkable. Magnetic resonance imaging (MRI) of brain with contrast had been normal. He was prescribed Flunarazine 10 mg daily. At 6 months' follow-up he had much improved and noticed the exploding head symptom only on two occasions.
Case 2
A 65-year-old man was seen in February 2007. He was hypertensive and diabetic (both well controlled on oral medication) and had been having infrequent attacks of International Headache Society migraine headache (every 2–4 months) without aura since the age of 15 years. For the past 4 months prior to consultation, every 2–3 weeks, he had been awakened while going off to sleep only during taking a daytime nap by a sudden exploding (like a bomb bursting) noise in his head lasting for only few moments.
This noise was always accompanied with jerky elevation of his right arm and a queer sensation in the right side of his chest (not arm) and again lasting only momentarily. He felt quite well on waking up and could go off to sleep again. These were never accompanied by any visual flashes and never occurred during sleep at night. These sensations were very different from his migraine headaches, which lasted for several hours and the noises were not accompanied by any nausea or vomiting.
Physical examination was normal and his blood presswure in the clinic was 136/80 mmHg. He had already had a MRI of brain with contrast, MR angiography of brain and two interictal sleep EEG recordings performed before consultation with the author, all of which were normal. A video EEG with daytime sleep recording was performed, but no event could be captured.
Link to article with case studies. Link to PubMed entry for same.
It's now well known that high altitude mountain climbing damages the brain and causes a marked reduction in mental functioning.
I naively assumed this was true for everyone but I just found an intriguing 1996 study that compared brain function of lowland mountain climbers and Nepalese Sherpas after ascent to high altitude, which found that the Sherpas suffer few of these neurological problems.
Are Himalayan Sherpas better protected against brain damage associated with extreme altitude climbs?
Garrido E, Segura R, Capdevila A, Pujol J, Javierre C, Ventura JL.
Clin Sci (Lond). 1996 Jan;90(1):81-5.
1. The potential risk of brain damage when low-landers attempt to climb the highest summits is a well-known fact. However, very little is known about what occurs to Himalayan natives, perfectly adapted to high altitude, when performing the same type of activity.
2. Taking into account their long-life climbing experience at extreme altitudes, we examined seven of the most recognized Sherpas with the aim of performing a comprehensive neurological evaluation based on medical history, physical examination and magnetic resonance brain imaging. We compared them with one group of 21 lowland elite climbers who had ascended to altitudes of over 8000 m, and another control group of 21 healthy individuals who had never been exposed to high altitude.
3. While all of the lowland climbers presented psychoneurological symptoms during or after the expeditions, and 13 of them (61%) showed magnetic resonance abnormalities (signs of mild cortical atrophy and/or periventricular high-intensity signal areas in the white matter), only one Sherpa (14%) showed similar changes in the scans, presenting neurological symptoms at extreme altitude. The neurological examination was normal in all three groups, and no neuroimaging abnormalities were detected in the control group.
4. The significant differences, in both clinical and neuroimaging terms, suggest that Sherpa highlanders have better brain protection when exposed to extreme altitude. Although the key to protection against cerebral hypoxia cannot be established, it is possible that an increase in the usually short period of acclimatization could minimize brain damage in those low-landers who attempt the highest summits without supplementary oxygen.
Link to study of neurology of lowland climbers and Sherpas.
A 2003 study in Epilepsy and Behavior has some descriptions of the ecstatic seizures experienced by some patients with epilepsy.
They include intense erotic and spiritual experiences, feelings of become close to and blending with other people, and some sensations that couldn't be fully captured in words.
I've put some of the descriptions below because they sound absolutely wonderful:
Patient 1
The first seizure occurred during a concert when he was a teenager. He remembers perceiving short moments of an indefinable feeling. Such episodes recurred and a few months later evolved into a GTC [generalized tonic–clonic seizure]. He characterizes these sensations as “a trance of pleasure.” “It is like an emotional wave striking me again and again. I feel compelled to obey a sort of phenomenon. These sensations are outside the spectrum of what I ever have experienced outside a seizure.” He also describes cold shivering, increased muscle tension, and a delicious taste, and he swallows repeatedly. He enjoys the sensations and is absorbed in them in a way that he can barely hear when spoken to. When in a particular, relaxed mood, he can sometimes induce seizures by “opening up mentally” and contracting muscles. He denies any religious aspects of the symptoms. “It’s the phenomenon, the feeling, the fit taking control.” It lasts a few minutes and afterward he is tired with difficulties expressing himself for about 1 hour.
Patient 6
This man has a multifaceted symptomatology and a tendency to interpret bodily sensations as supernatural phenomena. Nevertheless, from the beginning of his forties, he experienced distinct, stereotypical attacks with a “change of concept of the surrounding world.” He reports an “oscillating erotic sensation, like twinkling polar light” in his pelvic region and down the inside of his thighs. This is described as different from sexual excitement, more like “an erogenous charge of the skin.” He may also have a clairvoyant feeling of a “telepathic contact with a divine power.” These sensations are of short duration and may be accompanied by faintness and followed by drowsiness. With carbamazepine treatment, the frequency of these attacks has been considerably reduced.
Patient 11
The attacks started in his first school year. The experiences are beyond what can be described in words. “I can sense the colours red and orange without seeing them. The feeling has an erotic aspect. It starts in the stomach and spreads upwards. It is pleasant, but not similar to ordinary joy. It is like an explosion.” In the close presence of another person, he can feel a sort of peculiar unification. An intense déjà vu sensation, a queer taste, and “gooseflesh” are also components of the seizures. As a child he was surprised that his friends denied having similar feelings, and he learned to keep them to himself. Sometimes these attacks evolved into CPSs with reduced consciousness and complex automatisms and afterward he had transient difficulties speaking. Before the diagnosis of epilepsy was made in his late teens, he was referred to a psychiatrist. A right-sided temporal lobe calcification was diagnosed by computed tomography at about 30 years, but he refused surgery. At 42, an expansion in the same region was found by MRI, and he was operated for an anaplastic oligodendroglioma. He was seizure-free for 6 years until recurrence of the tumor.
One of the striking things about epilepsy is how different each person's experience of having a seizure can be.
While it is stereotypically assumed to be a negative experience, some aspects can be remarkably beautiful.
The Russian author Dostoyevsky famously said of his epilepsy "I would experience such joy as would be inconceivable in ordinary life - such joy that no one else could have any notion of. I would feel the most complete harmony in myself and in the whole world and this feeling was so strong and sweet that for a few seconds of such bliss I would give ten or more years of my life, even my whole life perhaps."
There are several more case descriptions in the article, all of which have some aspect which touch at least the edge of ecstasy, if not the very heart of the experience.
I just noticed that neurotechnology analyst Zack Lynch has a forthcoming article in Epilepsy and Behavior on the latest developments in the commercial brain science field. Avid neuroscience fans may be familiar with most of it but the section on new technologies to cross the blood-brain barrier was eye-opening.
The blood-brain barrier (BBB) is a sieve-like border crossing that allows only certain molecules to pass from the blood into the brain.
It's remarkably restrictive and many molecules are just too big to get past, meaning that many drugs that could affect the brain are virtually useless, simply because they can't cross the border.
This has led neuroscientists to think of ways of smuggling, tunnelling and sneaking this these molecules past the barrier, and Lynch's article lists some of the latest technologies which aim to jump the fence.
• Implantable devices: Implantable pumps bypass the blood–brain barrier (BBB) and deliver highly accurate amounts of drugs to specific sites in the brain or spinal cord.
• Expression systems: A French company is circumventing the BBB using encapsulated cell technology (ECT), a polymer implant containing cells that provide continuous, long-term release of the therapeutic protein to the brain or eye.
• Receptor-mediated transport: Receptors that transport nutrients to the brain from the blood can be tricked into transporting therapeutic chemicals, peptides, and proteins across the BBB. Insulin, transferrin, and lipoproteins, for example, cross the BBB by facilitated transport, and can be combined with therapeutic proteins or other molecules to promote access to the brain.
• Cell-penetrating peptides: During the past decade, several arginine-rich peptides have been described, such as SynB vectors, which allow for intracellular delivery and BBB transport. The mechanism for this transport is unknown. A Swiss company is using cell-penetrating peptides to develop treatments for stroke and myocardial infarction.
• Focused ultrasound: Some research shows that focused ultrasound can temporarily open the BBB in a targeted area for a window of time. A seed stage company is working to commercialize this technology and improve it for use in humans.
• Nanoparticle formulations: Nanoparticle formulations refer to therapeutics encapsulated in nanoscale particles that can pass the BBB. Although there is great interest in using nanotechnology to improve neuropharmaceutical delivery to the brain, it will take some time to overcome challenges of this platform, including the need for intravenous delivery, manufacturing, and clearance by the liver.
Jonah Lehrer has an excellent piece in today's Boston Globe about how babies' brains develop and what psychologists are starting to understand about the infant mind.
It's largely riffing on the work of Alison Gopnik, one of the world's leading developmental psychologists, who has long argued that babies might be more conscious than adults and that we learn to filter the world and mentally manage its initial chaos.
While this less focused form of attention makes it more difficult to stay on task - preschoolers are easily distracted - it also comes with certain advantages. In many circumstances, the lantern mode of attention can actually lead to improvements in memory, especially when it comes to recalling information that seemed incidental at the time.
Consider this memory task designed by John Hagen, a developmental psychologist at the University of Michigan. A child is given a deck of cards and shown two cards at a time. The child is told to remember the card on the right and to ignore the card on the left. Not surprisingly, older children and adults are much better at remembering the cards they were told to focus on, since they're able to direct their attention. However, young children are often better at remembering the cards on the left, which they were supposed to ignore. The lantern casts its light everywhere.
I'm a bit sceptical of one bit of the article though, where it claims that babies have more neurons than adults, as researchers have only very recently attempted to make this estimate and, in fact, found that babies and adults have about the same in the cortex, which makes up the vast majority of the brain.
In terms of synapses, connections between neurons, this varies on the age of the infant. For example, have a look at this graph of synapse density as we grow, taken from a study of the human cortex.
Newborns start with fewer synapses than adults but this number rockets, so by six months of age we have approximately twice as many connections. This tails off as the brain prunes connections on a 'use it or lose it' basis.
I'm always slightly awestruck whenever I view that graph as it is a vivid illustration of the incredibly rapid changes changes that take place as we grow and learn to make sense of the world.
It's this same sense of awe that the Boston Globe manages to capture as it explains how understanding the baby's brain can help us make sense of the adult mind.
Link to Boston Globe article 'Inside the baby mind'.
The New Yorker has a fantastic in-depth article about 'cognitive enhancement' that talks to some of the neuroscientists studying the effects and some of the mind tweakers who regularly pop pills to give themselves an edge.
One of the issues it touches on is whether cognitive enhancers really 'enhance' people, and there's good evidence that for the highest achievers, the pills might not be of much benefit.
Even worse, it's also likely that the amphetamine-based drugs (Ritalin, Adderall) could actually impair your performance even though you might feel as if you've had a mental boost.
Amphetamine has the effect of increasing focus, confidence and giving a euphoric feeling. Although the effects are less marked in the slow release amphetamines used for ADHD and appropriated for illicit mind tweaking, the effect is certainly still there.
What we do know, however, is that people with certain genotypes actually show a decrease in working memory performance when they take amphetamine.
And it turns out that these are the people most likely to already be at the high end of mental performance. This is from a classic study on the effect:
Amphetamine enhanced the efficiency of prefrontal cortex function assayed with functional MRI during a working memory task in subjects with the high enzyme activity val/val genotype [of the COMT gene], who presumably have relatively less prefrontal synaptic dopamine, at all levels of task difficulty.
In contrast, in subjects with the low activity met/met genotype who tend to have superior baseline prefrontal function, the drug had no effect on cortical efficiency at low-to-moderate working memory load and caused deterioration at high working memory load
In other words, it's possible that high achievers might be popping stimulants, feeling like it boosts their performance, when in fact, it's doing exactly the opposite.
The article explores more than just this area though, and is incredibly wide-ranging, looking at the neuroscience, the underground use of the drugs, legal aspects, new and current compounds, and so on.
It's also one of the most interesting articles I've read on the subject for a while, which, for an area which attracts of lot of attention, has got to be a good thing.
Link to 'The underground world of “neuroenhancing” drugs'.
Newsweek has an excellent article on the neuroscience and personal impact of epilepsy. It's well-researched, gripping in parts and bang up-to-date as it takes us through how neurologists tackle the seizure-prone brain.
I was particularly impressed by the following section as it avoids the common cliché of the epileptic 'brain storm' because, as we've discussed before on Mind Hacks, a seizure is not a storm of random brain activity.
In fact, it's completely the opposite. During a seizure neurons become super-synchronised, pulsing together, so they can't do their normal job. In effect, it's an anti-storm.
Conceptually, the job of the cardiologist is straightforward: he needs to restore a damaged heart to its normal rhythm. But epilepsy is the opposite. A normal brain is governed by chaos; neurons fire unpredictably, following laws no computer, let alone neurologist, could hope to understand, even if they can recognize it on an EEG. It is what we call consciousness, perhaps the most mathematically complex phenomenon in the universe.
The definition of a seizure is the absence of chaos, supplanted by a simple rhythmic pattern that carries almost no information. It may arise locally (a "partial" seizure), perhaps at the site of an old injury, a tumor or a structural malformation. A network of neurons begin firing in unison, enlisting their fellows in a synchronous wave that ripples across the brain.
Or it may begin everywhere at once ("generalized" epilepsy), with an imbalance of ions across the cell membrane, usually the result of an inherited mutation. At a chemical signal, whose origin is still a mystery, billions of neurons drop the mundane business of running the body and join in a primitive drumbeat, drowning out the murmur of consciousness. And so in contrast to the cardiologist, the epilepsy doctor must attempt to restore not order, but chaos.
The article is very much epilepsy from the medical perspective, but it is probably the single best mainstream piece I've read that attempts to tackle this area.
If you only read a handful of epilepsy articles in your life, make this one of them. Well done Newsweek.
Link to Newsweek article 'In the Grip of the Unknown'.
Discover Magazine has an interesting Carl Zimmer article on one of the most intriguing questions in neuroscience - why do we have two cortical hemispheres? And why are they not quite the same?
It turns out that the 'brain of two halves' is incredibly common in the animal kingdom and that many creatures also show the behavioural lateralisation that we most readily see in humans as someone being left or right handed.
But it's no entirely sure why we, or indeed, or animal compatriots, have evolved this way, although various theories are kicking around:
David Stark of Harvard Medical School recently found additional clues about lateralization in his studies of 112 different regions in the brains of volunteers. He and his collaborators discovered that the front portions of the brain are generally less tightly synchronized across the hemispheres than are the ones in the back. It may be no coincidence that the highly synchronized back regions handle basic functions like seeing.
To observe the world, it helps to have unified vision. At the front of the hemispheres, in contrast, we weave together streams of thought to produce complex, long-term plans for the future. It makes sense that these areas of the brain would be more free to drift apart from their mirror-image partners.
Zimmer goes on to puncture the myth of 'left brained' and 'right brained' people, or indeed, thinking styles, erroneously labelled with these pseudoscientific terms.
While certain cognitive styles have been correlated to greater activation in the left or right hemisphere, to describe a whole class of problems of thinking methods like this is nonsensical because the two hemispheres of the brain work together.
It's like claiming someone is a good cook solely because they come from Italy. The generalisation is so broad it just doesn't apply to individual people or situations.
Anyway, the Discover article is an excellent whistle-stop tour through the curious world of brain lateralisation.
Link to Discover on the brain of two hemispheres (via @mocost).
I've just found this fascinating case study in American Journal of Physical Medicine and Rehabilitation about a man who lost conscious control over one of his hands after brain injury and suffered involuntary public masturbation episodes as a result.
Involuntary masturbation as a manifestation of stroke-related alien hand syndrome
Ong Hai BG, Odderson
Am J Phys Med Rehabil. 2000 Jul-Aug;79(4):395-8.
Alien hand syndrome is a perplexing and uncommon clinical diagnosis. We report an unusual manifestation of alien hand syndrome in a 73-yr-old man with a right anterior cerebral artery infarct affecting the right medial frontal cortex and the anterior portion of the corpus callosum. We conclude that alien hand syndrome should be considered in patients who present with a feeling of alienation of one or both upper limbs accompanied by complex purposeful involuntary movement.
We tend to think of the cognitive impairments after brain injury as the most disabling - things like loss of memory or speech or language impairment, but we often neglect what we might call social impairments.
Especially when the effect is embarrassing, these can have just as strong an impact because many people massively restrict their lives to prevent causing social discomfort to themselves or others.
I am pleased to see a letter in this week's Nature that shows that I'm not the only neuroscientist concerned about the coming robot war. Brain researchers Olaf Blanke and Jane Aspell wrote in to warn about the use of brain-machine interfaces, not to control machines with thoughts, but to control thoughts with machines.
Imagine if insights from the field of cortical prosthetics in human and non-human primates were combined with research on bodily self-consciousness in humans. Signals recorded by multi-electrodes implanted in the motor cortex can already be used to control robotic arms and legs. Cognitive cortical prosthetics will allow the use of other cortical signals and regions for prosthesis control. Several research groups are investigating indications that the conscious experience of being in a body can be experimentally manipulated.
The frontal and temporoparietal signals that seem to be involved encode fundamental aspects of the self, such as where humans experience themselves to be in space and which body they identify with (O. Blanke and T. Metzinger Trends Cogn. Sci. 13, 7–13; 2009). If research on cortical prosthetics and on the bodily self were applied to humans using brain-controlled prosthetic devices, there might be no clear answer to Clausen's question: which of them is responsible for involuntary acts?
It may sound like science fiction, but if human brain regions involved in bodily self-consciousness were to be monitored and manipulated online via a machine, then not only will the boundary between user and robot become unclear, but human identity may change, as such bodily signals are crucial for the self and the 'I' of conscious experience. Such consequences differ from those outlined by Clausen for deep brain stimulation and treatment with psychoactive drugs.
The letter is a follow-up to a recent Naturepiece on potential new ethical issues raised by the development of implantable brain technology.
Unfortunately, these sort of in-house scientific debates rarely do much to raise the public consciousness about the importance of such issues.
However, I have high hopes for the future. Not least because a new film in the Terminator documentary series is soon to be released.
In C.S. Lewis' Narnia novelThe Voyage of the Dawn Treader the heroes find a man stranded on an island where dreams come true. They initially express delight but the man rages "Fools!" "Do you hear what I say? This is where dreams - dreams, do you understand? - come to life, come real. Not daydreams: dreams."
But dreams can come to life and the effect is no less fantastical. In REM sleep behaviour disorder (RBD), normal sleep paralysis breaks down and sleepers act out their dreams - giving observers a remarkable insight into the dreaming mind.
An article recently published in Neurology charted the range of sleep behaviours seen in people with neurological disturbances such as narcolepsy, Parkinson's disease or other types of dementia, all of which can trigger the problem.
Incidental cases of nonviolent behaviors during RBD included masturbating-like behavior and coitus-like pelvic thrusting, mimicking eating and drinking, urinating and defecating, displaying pleasant behaviors (laughing, singing, dancing, whistling, smoking a fictive cigarette, clapping and gesturing "thumbs up"), greeting, flying, building a stair, dealing textiles, inspecting the army, searching a treasure, and giving lessons. Speeches were mumbled or contained logical sentences with normal prosody [voice tone, rhythm and stress].
The paper also contains two case studies which describe, in detail, exactly what each patient was doing when they were acting out their dreams. This is from the description of 'Patient 2':
These behaviors, which occurred with eyes closed, were complex, various, and usually accompanied with sentences resembling a teacher with children (first sequence) or a captain inspecting his troop (second sequence): “(Professorial) Can we all return to our seats! (pause) (Overbearing) What do you do, standing there in the middle? (pause) Remove your finger away from the switch! (pause) Well, if that’s so, I’ll take the numbers. (Ironic) And . . . late! (pause). (Professorial) Get back to your seats. I’m going to start.”
Mumbles for 6 minutes. Then: “(bossy) Raise your hands, raise your hands, raise your hands, I said raise! I didn’t say to pull away! I said: raise your hands!” Here the patient quickly raised his left arm and waved his hand it as if he were showing something. “(Bossy and rhythmic) Halt! (pause) Halt! (pause) Halt!” Three minutes later, he shouted “(Bossy, like in a military parade) Attention! Gentleman, please, attention! (pause) Halt, halt, I said! (pause) Halt, I said!”
This study specifically focused on the less researched non-violent sleep behaviours, as the disorder is more typically associated with acting out aggressive dreams.
This is possibly because the disturbances that cause the disorder also affect the content of the dreams.
An earlier study found that patients with the disorder reported having more aggressive dreams, even though they were not more aggressive in waking life.
It's a fascinating article and worth reading in full as it contains many 'wow, that's amazing' moments, both for the scientific insights, and the windows into the mental life of sleep.
Link to Neurology article on sleep behaviours. Link to PubMed entry for same.
For the first time, the brain structure of male-to-female transsexuals has been investigated in living individuals using MRI brain scans, helping to fuel the debate over the possible neural basis of gender identity.
The scientific article, shortly to appear in the neuroscience journal NeuroImage, used MRI brain scans and a technique called voxel based morphometry to compare grey matter in a group of male-to-female transexuals to groups of males and females who have never had gender-identity concerns.
This is not the first time that brain structure has been compared in this way, but earlier studies had been based on post-mortem comparisons. Thesethreestudies had found that certain areas in male-to-female transsexuals more commonly resembled the equivalent area in females than males.
This has led some researchers to go as far as suggesting that perhaps the differences are present from birth and that gender-identity difficulties could result from the body and brain following different paths as the developing foetus begins to develop into a specific sex.
However, one difficulty is that all the transgender people examined in these post-mortem studies had been on oestrogen treatment to feminize their bodies, and it hasn't been clear whether the differences were due to the effect of this hormone rather than something present before.
This new study, led by neuroscientist Eileen Luders, specifically recruited male-to-female transsexuals who had never taken oestrogen and, being in living people, wasn't affected by whatever led to the person's death.
In contrast to previous investigations, this new study found that male-to-female transsexuals grey-matter was similar in most areas of the brain to the male rather than female comparison group.
Except, that is, for one area, the putamen, a deep brain structure that forms part of the basal ganglia - known for its wide range of functions and connections to the frontal lobes and action control areas.
Because we know so little about the neuroscience of self-image and gender-identity it's almost impossible to draw any conclusions for the fact that this specific area seems more 'feminine', or that the majority of the other areas seem more 'masculine' in terms of size.
What this study does do, however, is add to the increasing evidence that there are some detectable neurological differences in the brains of transgendered people. We're just not in a position to say much about the significance of this yet.
New Scientist has an excellent cover article on 'The five ages of the brain', looking at how the brain changes as we grow and how these transformations are reflected in our lives.
Each gives a concise introduction to some of the latest findings on how the brain differs in each time period, although for a slight counter-point, I would recommend a recent edition of ABC Radio National's All in the Mind.
The programme takes a sceptical look at the emerging neuroscience of adolescence, largely based on the fact that adolescence as a distinct developmental stage is a relatively recent cultural invention of the Western world.
Psychologist Robert Epstein argues that the differences in the teen brain are relatively minor, and that the stereotype of the 'teen in turmoil' is not a biological fact of brain development, but a result of the cultural pressures put upon adolescents.
The NewSci collection and the All In the Mind programme complement each other nicely and tackle some of the current hot issues in developmental neuroscience.
Link to NewSci 'Five Ages of the Brain' special. Link to AITM on 'The modern teenager: myth or marvel?'
Rendered frantic, crazy by unbroken concentration:
Advances in the History of Psychology has just alerted me to a fascinating short article on the work of the influential 18th-century physician Samuel Tissot, who wrote a book arguing that concentrating on books for too long damaged the mind.
The 18th century was when books were becoming cheap enough to be widely available to the middle classes and it's interesting that this new cultural development produced a similar pseudo-medical concern about damage to the mind that we often hear today, but in a completely different direction.
While modern day technological doom-sayers suggest that technology damages the mind because it interrupts concentration, 18th century technological doom-sayers suggested that reading damaged the mind because it required too much concentration.
Neither have an evidence base, but I maintain a morbid interest in medicalised concerns about new technology and cultural innovations, which often take the same basic form but cite a cause which is always curiously in line with the authors' prejudices.
It turns out Tissot, like many of this medical contemporaries, was also obsessed with masturbation, which he cited as the cause of madness and a host of other psychological problems.
Catholic church aside, it seems a ridiculous view to us now, but it was widely held by some of the most prominent and influential medical men of the time.
Link to Guardian 'Beware: studying can make you ill'. Link to AHP on 'Read Till You’re Crazy'.
Wired has an excellent article on the Allen Institute for Brain Science's ambitious mission to map where each gene is expressed in the brain.
We tend to think of genes in terms of their ability to pass on characteristics to new generations, but the moment the egg and the sperm combine, genes start coding for proteins which the body uses to do its work.
Of course, this includes the brain, so knowing what type of genes produce proteins in which areas of the brain gives us a big clue to some of the brain's functions.
The article is, perhaps, a little overly hopeful about the significance of a having a gene map for understanding complex mind functions or disorders (autism is mentioned as an example) - suggesting that some research hits a dead end without it.
Perhaps something useful to mention is that one of the key pieces in the puzzle of gene expression in the brain is not where genes are expressed but under what conditions they are expressed.
While your DNA has the ability to express every protein it has genes for, the cell regulates this process so it reacts to current conditions dynamically.
In other words, the genes are more of a reference book, and the cell's other regulation processes decide how and when to use this information.
As far as we know, all learning in the brain happens through proteins, meaning that experience, learning, thought, motivation - or any other 'psychological level' process we can think of, acts through the many, complex and not fully understood regulation processes.
So understanding the reference book is an essential but insufficient part of the picture. The real deal is in understanding how the brain's cellular workers use the information to mediate between genes and the processes we understand at the psychological, behavioural or experiential level.
This is part of the new science of epigenetics, and there are high hopes that this will be a big part of future neurobiology.
This doesn't imply that we don't need to understand the role of experience and the environment in deference to purely reductionist neurobiological models. In fact, these new developments have stressed the importance of integrating these bigger concepts.
And this is largely because we now have the beginnings of a science that could help us make links between these different levels of explanation.
Nevertheless, the Allen Brain Atlas is an important and exciting part of this new science and the Wired article is a great introduction to the project.
Link to Wired article 'Scientists Map the Brain, Gene by Gene'. Link to Wired image gallery of the Allen project.
The New York Times has an obituary for Earl Wood, the man who invented the G-suit, the pressurised suit for fighter pilots that prevents them losing consciousness when g-forces drain blood from the brain.
The problem became apparent as fighter plane technology advanced to the stage where they became so fast and manoeuvrable that pulling tight corners or sharply accelerating put huge strains on the pilots' bodies.
The acceleration temporarily impedes the heart’s pumping power and cuts blood supply to the brain. A tight turn might cause the pilot to lose consciousness briefly, leading to a crash...
To counter a precipitous drop in blood pressure, the team designed a suit that placed air bladders at a pilot’s calves, thighs and abdomen; a valve inflated the bladders as G-forces increased. Constriction of the bladders on the arteries raised blood pressure and helped keep blood flowing to the brain. The suit’s prototype was tested successfully by Dr. Wood and others in a dive bomber on flights that involved steep descents.
At the same time, the Mayo team developed an exercise, called the M1 maneuver, in which a pilot would shout or grunt under G-force conditions. The grunting compressed arteries and tensed muscles and was at least as important as the revolutionary suit for resisting G-forces.
Permanently altering brain function, outside the skull:
A surgical team from Italy have just reported that they've altered human brain function through neurosurgery conducted from outside the skull, by using beams of radiation.
The technique is known as radiosurgery and, in itself, isn't novel. The team used the Cyberknife system, specifically designed to do this sort of operation.
However, the technique is typically used to treat brain tumours, and what is new is that the team have adapted this method to permanently knock out targeted areas to alter overall brain function.
They were inspired by deep brain stimulation and functional brain surgery. These aim to do a similar thing and are most commonly used to treat tremors and movement problems in Parkinson's disease by altering the movement circuits in the brain.
This new operation aimed to do something similar, but with radiosurgery.
Their report appears in the journal Medical Physics, where they describe the treatment of two patients with, until then, untreatable disorders. One with chronic pain, stemming from nerve damage, and other with dystonia, a neurological disorder that causes certain muscles to painfully contract.
One of the challenges with this sort of operation is hitting exactly the right spot, and to achieve the necessary accuracy the team built a 3D computer model of the key areas from the brain scans which they then used to electronically direct the radiosurgery equipment.
The patient with dystonia had a pallidotomy, where part of his basal ganglia was ablated (destroyed), whereas the patient with chronic pain had a thalamotomy, taking out a section of his medial thalamus.
Both patients recovered well, significantly improved and showed no major side-effects at 15 months.
The image on the left shows where the radiation beams entered the head during the operation on the patient with chronic pain.
Link to research report. Link to PubMed entry for same.
Sweet anaesthesia and the mystery of consciousness:
Discover Magazine has an excellent article on the science of anaesthesia and why doctors need to struggle with the problem of consciousness to make someone comfortably numb.
If you're not familiar some of the mysteries of anaesthesia, you may be surprised to know that we don't actually know how most anaesthetics work and we have no reliable way of telling whether someone is unconscious.
This is important because general anaesthesia usually involves two types of drug, muscle relaxants and hypnotics. It's possible that the muscle relaxants have their paralysing effect but the hypnotics don't fully work, so you're awake and aware, but don't respond when you're touched or talked to.
Hence anaesthetists would love a device which says whether someone is concious or not, but unfortunately, divining consciousness from the brain is one of the hardest problems in science. So, they've come up with various other methods:
Sometimes the anesthesiologist will use a blood pressure cuff on a patient’s arm to block the muscle relaxants in the bloodstream. Then the doctor asks the patient to squeeze a hand.
This sort of test can distinguish between a patient who is awake and one who is out cold. But at the borderline of consciousness, it is not very precise. The inability to raise your hand, for example, doesn’t necessarily mean that you are unconscious. Even a light dose of anesthesia can interfere with your capacity to keep new pieces of information in your brain, so you may not respond to a command because you immediately forgot what you were going to do. On the other hand, squeezing an anesthesiologist’s hand may not mean you’re wide awake. Some patients who can squeeze a hand will later have no memory of being aware.
Seeking a more reliable measuring stick, some researchers have started measuring brain waves. When you are awake, your brain produces fast, small waves of electrical activity. When you are under total anesthesia, your brain waves become deep and slow. If you get enough of certain anesthetics, your brain waves eventually go flat. Most anesthesiologists monitor their patients using a machine known as a bispectral index monitor, which reads brain waves from electrodes on a patient’s scalp and produces a score from 100 to 0. But these machines aren’t precise either. Sometimes patients who register as unconscious can still squeeze a hand on command.
The article then goes on to discuss some fascinating neuroscience studies that use anaesthesia to try and understand what changes in the brain as someone slips into unconsciousness.
It's a great read and an interesting look into what you might called 'applied consciousness research'.
Link to 'Could a Dose of Ether Contain the Secret to Consciousness?'
Frontiers in Human Neuroscience has a great two page article that nicely summarises the thinking about how blood flow measured by brain scans relates to the workings of the neurons.
No one with common sense would believe that in a house, water movements in pipes could tell you how many lamps are on and how much fuel is used for heating. Surprisingly most neuroscientists are convinced that in the brain monitoring local cerebral blood flow (CBF) what I call plumbing, is a reliable surrogate method to localize electrical neuronal activity and monitor metabolic events.
The piece is by neuroscientist Jean Rossier, and he discusses the two main theories of how blood flow relates to what the neurons are doing.
The 'metabolic hypothesis' assumes there is a causal link between how much energy the neurons need, in the form of glucose, and the subsequent regulation of blood flow in the brain. In other words, the neurons signal the need for energy, which is delivered later.
The 'neurogenic hypothesis' hypothesis, suggest that blood flow can be 'pre-ordered', in anticipation of neural activity.
Needless to say, it's important to understand the exact relation between the operation of the neurons and blood flow, because brain scanning studies typically measure blood flow to infer the working of neurons and hence the relationship to cognitive or mental processing.
The Frontiers in Human Neuroscience article is a concise piece which discuss the neuroscience of this link, and covers some of the most recent studies which have attempted to make sense of what brain scans tell us when we're doing psychology experiments.
Link to article 'Wiring and plumbing in the brain'. Link to PubMed entry for same.
I like this sentence in the summary from a recent paper on an unusual penetrating head injury:
We present a unique instance of a severe, high-energy, penetrating orbitocranial injury caused by a solid metallic rod that corresponded to the spray valve lever handle of a kitchen sink pre-rinse spray tap, which was fractured and projected at high speed for an unknown reason.
An article just published online for the Behavioural Science and Law journal discusses whether magnetic brain stimulation could be used in lie detection and interrogation.
It is based on the premise that as cognitive neuroscience works out the brain circuits for lying, a technique called transcranial magnetic stimulation (TMS) could be used during an interview to disrupt the function of these pathways.
The article specifically pitches this idea as a possible 'lie detection' method, as so far, research conducted by the authors suggest that disrupting parietal cortex function, on average, slows the response time for lies and but doesn't affect response time for truthful responses - albeit in a very controlled laboratory experiment.
In other words, the idea is that TMS could be used to help distinguish truthful responses from untruthful ones.
My first thought on reading this was that someone is bound to be thinking of this technique as a way of inhibiting the relevant circuits to prevent lying, or at least increase the likelihood of truthful responses.
It's probably true to say that deception research is in its very early days and its not even clear whether such things as distinct 'deception circuits' even exist.
However, from what we know from now-public secret military research in this area, it's clear that many of these sorts of techniques are simply tested empirically.
Essentially, whether there is a good theoretical basis or not, national security agencies are much more likely simply to try the techniques and see what the outcome is.
The Behavioural Science and Law article sticks firmly to the possible civilian uses for this technology, discussing the legal and ethical issues within a domestic law framework, but you can bet that the spooks are already thinking ahead on this one.
Link to 'Non-invasive brain stimulation in the detection of deception'. Link to PubMed entry for same.
We've reportedbefore on brain imaging research that shows brain activity in those in a 'persistent vegetative state'. What I didn't know until today was that one subject in this research, Kate, has since woken up. This YouTube video tells Kate's story:
Kate suffered from what was probably brain stem encephalitis at the age of 23. She was the first patient to be scanned by Adrian Owen as part of his research into the mental lives of those in persistent vegetative states. Findings from this research support what Kate herself is able to say in the video: we need to be very careful before making life and death decisions on behalf of people who appear unresponsive.
Wired has just published an excellent twopart article on neuroengineering, the practice of altering the brain with electronics or optics.
It looks at a number of interesting projects, from light controlled neurons to magnetic brain stimulation, and focuses on the work of talented neuroengineer Ed Boyden who I had the pleasure of doing a joint talk with at a SciFoo conference.
In fact, TMS gets electricity into the brain peacefully, without either cutting it open or shocking it with millions of volts.
The target area of the brain is treated like the coil in a generator, subjected to rapidly changing magnetic fields until electricity begins to dance across its neurons. Unlike the optical switch developed by Boyden and Stanford's Dr. Karl Deisseroth, TMS doesn't reach the deeper regions of the brain, but there are a lot of important and interesting areas in the cortex where TMS delivers its current. It's also far less precise than the optical switch, although TMS seems positively surgical when compared to the imprecisions of the pharmaceuticals we pump into our bodies.
The second part is probably the highlight, discussing the possibilities of having these technologies more widely available so your average garage hacker can tinker with them (and themselves), and what ethical dilemmas this might cause.
Link to 'Inside the New Science of Neuroengineering'. Link to 'How Neuroengineering May Change Your Brain.
Brain implants and cognitive side-effect trading :
This week's Nature has an interesting article on the ethics of electronic brain enhancements. It does something quite unusual for an article on technological brain enhancements - it talks about the side effects.
Brain implants and 'neuroprosthetics' have been widely covered by the science media in recent years owing to a number of impressive advances but very little discussion has focused on the adverse effects.
In considering the ethics of using brain implants to enhance both the damaged and healthy brain, this article actually touches on some of the research on unwanted effects of deep brain stimulation.
Many patients with Parkinson's disease who have motor complications that are no longer manageable through medication report significant benefits from DBS. Nevertheless, compared with the best drug therapy, DBS for Parkinson's disease has shown a greater incidence of serious adverse effects such as nervous system and psychiatric disorders and a higher suicide rate. Case studies revealed hypomania and personality changes of which the patients were unaware, and which disrupted family relationships before the stimulation parameters were readjusted.
Such examples illustrate the possible dramatic side effects of DBS, but subtler effects are also possible. Even without stimulation, mere recording devices such as brain-controlled motor prostheses may alter the patient's personality. Patients will need to be trained in generating the appropriate neural signals to direct the prosthetic limb. Doing so might have slight effects on mood or memory function or impair speech control.
The author of the piece argues that this does not raise any new ethical questions, as many psychiatric drugs also have side effects.
However, it's probably true to say that ethical difficulties often arise with regard to specific side effects - talking about unwanted effects in general is a bit too vague to be useful.
Risk-benefit analyses are only useful when you know both the extent and quality of the risks and benefits and this is where it truly gets interesting.
The neuropsychology literature is full of surprising findings about what sort of functions the brain performs, suggesting that specific effects, wanted and unwanted, may have to be traded off against each other.
For example, is the loss of the ability to have an unconscious emotional reaction to a loved one worth a change in pathological gambling behaviour?
This is a hypothetical example based on the role of the ventromedial cortex in bothsituations, but who knows what sort of effects might need to be weighed up against each other.
Nature Network has an online discussion about the issues the piece raises which also links to the weekly podcast which has an interview with the author.
Link to Nature article 'Man, machine and in between'.
I've just found this remarkable CT scan in a 1997 article entitled 'Trans-orbital penetrating head injury with a door key'.
The paper reports that "A 71-year-old-female was answering the door when she misjudged the step and fell forward impaling herself on the large key protruding from the lock."
She was found with the key still embedded in her head and was transferred to neurosurgery where the key was removed.
Thankfully, the patient recovered with no neurological impairment and only slight difficulties with her vision.
Time magazine has an interesting article on the neuroscience of spiritual experience and why religious belief has been linked to better health.
It's not the most gripping article in the world and starts with some annoying experience = brain area phrenology but it does gives a good overview of some of the main research areas.
Probably the most interesting aspect is where it tackles the link between religious belief and health in light of other belief based health benefits such as the placebo effect or beliefs about illness itself.
The section on the effects of prayer also has this fascinating snippet about early experimental psychologist Francis Galton:
As long ago as 1872, Francis Galton, the man behind eugenics and fingerprinting, reckoned that monarchs should live longer than the rest of us, since millions of people pray for the health of their King or Queen every day. His research showed just the opposite — no surprise, perhaps, given the rich diet and extensive leisure that royal families enjoy.
Studies on the curative properties of prayer have a long and interesting history, with one of the most striking moments also linked to a psychologist and an (in)famous study - discussed in a 2002 Wiredarticle.
Stanford University have put a series of engaging TED style 10 minute lectures up on YouTube where some of their leading researchers discuss cutting-edge cognitive science research - curing blindness with neural implants, brain computer interfaces, neural pathway mapping, creating brain inspired computer hardware, visualising desire and controlling neurons with light.
Getting lab scientists to do short, engaging online lectures aimed at a bright and curious audience is a fantastic idea. These new Stanford talks have a high production quality and have obviously been prepared with a great deal of care as they are incredibly easy to watch.
I've not watched them all yet, but so far the talk on the neuroscience and stem cell treatment of blindness is a particular highlight.
In this presentation, psychologist Brian Wandell discusses the science of perception and the treatment, as well as the remarkable case of Mike May, the world-record holder for blind downhill skiing who volunteered to try the experimental treatment.
A fantastic series that's well worth checking out.
Locked-in syndrome is a dramatic condition where, after brain stem damage, patients are conscious but paralysed and can only communicate with the outside world by an eye-blink or muscle twitch.
Because of limited communication it has been difficult to assess the impact of the damage on thinking and reasoning, but a French team have created tests that can be completed by simple yes / no movements - allowing the first comprehensive study into the cognition of the locked-in mind.
The syndrome usually occurs after a stroke, where an interruption to the blood supply selectively damages the neurological 'relay station' that transmits movement impulses to the rest of the body, leaving an almost total paralysis - classically except for a facial muscle.
It has been assumed that affected people are paralysed but cognitively intact - their thinking isn't affected.
In one famous example, the editor of Elle magazine, Jean Dominique Bauby, wrote the bookThe Diving Bell and the Butterfly after suffering locked-in syndrome by painstakingly selecting letters with an eye-blink. It's both stunningly beautiful and eloquent, demonstrating a keen and focused mind.
But because of extremely limited communication, it's difficult to say whether this level of preserved mental ability is common because traditional neuropsychological tests usually require relatively complex responses.
To address the problem, a French team, led by neurologist Marc Rousseaux, designed tests to assess nine patients that included everything from visual recognition tasks to logical-mathematical reasoning problems, all which could be answered with yes / no responses - just eye-blinks in some cases.
The appendix of their article has the full list of the tests and they are remarkable for their ingenious design.
They team found that while the patients were generally mentally sharp, problems in particular areas were not uncommon, with a significant minority showing selective impairments in areas such as comprehension, understanding meaningful connections, or problem solving.
Sadly, this means that it is unlikely that all locked-in patients share Jean-Dominique Bauby's remarkably preserved intellect, but the development of these ingenious tests means that we can better understand the impact of the syndrome, and the strengths and weakness of affected patients.
The long term effects of banging heads on the field:
Sportsmen who suffer concussion in early adulthood may experience long-term reduction in brain function well into later life, according to a study released this week.
Although the study had only 40 participants, it is striking as it looked at the effects 30 years after the original concussions and used a wide and diverse range of tests for cognitive and neurological function, the majority of which showed some level of impairment.
This comes in the same week that Boston University School of Medicine reported that former American football player, Tampa Bay Buccaneer Tom McHale, was suffering from chronic traumatic encephalopathy (CTE), a degenerative brain disease caused by head trauma, when he died in 2008 at the age of 45.
CNN has a good write-up of the news with photos and images of the long-term effects of persistent sports concussion and we covered the work of Dr Bennet Oamlu, who does post-mortems on cognitively impaired American football players, back in 2007.
Repititive sports concussion is now recognised as having a significant neurological impact and has also been found in rugby and boxing.
Interestingly, ex-professional football players (known as soccer players to Americans and other football philistines) probably have higher levels of dementia and there is an ongoing debate about whether this is due to the low level impact of heading the ball.
Some think it is, other think it might be due to the fact footballers consume a lot of alcohol, and so the higher levels of dementia just might be wear and tear from all the booze.
Link to full text of long-term sports concussion study. Link to CNN on sports concusion and dementia (via NeuronCulture).
Neuroscience textbooks often suggest that the ability to image the structure of the brain in living patients started in the 1970s with the introduction of the CT scanner. What they tend to forget is that brain surgeon Walter Dandy was already neuroimaging patients as early as 1918.
We think of x-rays as only being useful for getting pictures of bones but soft tissue does show up on an x-ray.
The images rely on certain bits of the body having a higher density and therefore blocking more of the rays falling on the photographic plate.
Bones are obviously very dense so show up well but look at this image of a hand x-ray. You can clearly see the difference between bone, flesh and air. What you can't see is any difference in the soft tissue.
The crucial difference that struck Walter Dandy was the possibility of distinguishing flesh and air on an x-ray.
Knowing that the brain is surrounded by cerebrospinal fluid (CSF), which also fills internal spaces called the ventricles, he decided to simply replace the fluid with air and x-ray the patient.
He published his first results in 1918. He described how he drilled a hole in the skull of a patient and carefully removed the CSF from the ventricles and replaced it with air.
Now known as ventriculography, one of the images he took is illustrated on the top left. For the first time, you could clearly see the ventricles in a living patient.
During the procedure, he noted that some of the air has escaped the ventricles and was occupying the space between the skull and the brain.
The following year he published another study where he deliberately filled this space with air as well, so the surface of the brain was surrounded by the gas and so could show up on an x-ray.
The bottom left image shows the result of this, and you can see it clearly shows some of the 'trenches', the cerebral sulci, on the surface of the brain.
Now called pneumoencephalography, the procedure was immensely useful, but, extremely unpleasant. In his 1918 article he noted that the patient's reaction "was characterized by a rise of temperature, nausea, vomiting, and increased headache".
Furthermore, it takes weeks, if not months, for the CSF to be replaced by the body, leaving the patient in a debilitated and fragile state.
However, it was used throughout the 20th century and the research literature is peppered with the results of this early neuroimaging research.
Link to 1918 paper on imaging of the ventricles. Link to 1919 paper on imaging the brain surface.
The great British neurologist John Hughlings-Jackson famously described the 'dreamy state' reported by some epileptic patients during seizures where they experienced complex hallucinations - sometimes of scenes and faces, feelings of false familiarity and a feeling of 'weirdness' or 'strangeness'.
A study published last year in neurology journal Brain re-examined these experiences by deliberately triggering them by electrically stimulating the brain.
The participants were all patients with epilepsy who were having neurosurgery to treat their otherwise untreatable seizures and the researchers, led by neurologist Jean-Pierre Vignal, specifically stimulated areas in the mesial [inner] temporal lobes.
The feelings of false familiarity are what we normally called déjà vu, but actually we tend to misapply this term as it means 'already seen' and refers specifically to a false familiarity for visual perception.
However, it can also occur for anything we experience, such as hearing other people say things, and is more correctly called déjà vécu ('already experienced') in the literature.
Here are a few of the triggered experiences:
Déjà vécu (3 volts, right amygdala) - "It's like yesterday evening ... I have the impression that everything around me has been here before, that it has already happened, I feel as if I am going backwards in time"
Scene: reliving a parachute jump (3.5 volts, right hippocampus)
Familiar television advertisement (4 volts, right amygdala)
Impression of being elsewhere (3 volts, right hippocampus)
Scene from childhood (2 milliamps, right amygdala) - "Vision of a bald man dressed in black, coming towards her from behind; associated with a feeling of imminent death; she is pale, with piloerection. She is re-experiencing an experience of anaesthesia by facemask during a tonsillectomy at the age of 14 years"
Impression of being someone else (2 milliamps, left amygdala)
Impression of leaving his body (2.5 milliamps, left amygdala)
Night-time scene (1.2 milliamps, left hippocampus) - "I'm starting to see lots of things, loads of people ... it's still vague and strange. I've got an initial picture, a memory ... I feel locked in again, something to do with the evening, the night ... it's strange ... . like after a party, sad things ... there is a mixture of last night and this morning ... ’ These remarks were peri-ictal [during the seizure]. After the end of the discharge, there was complete amnesia."
Scene (4 milliamps, right hippocampus) - "It's starting, it's rising up to my eyes ... I'm always frightened of something ... I feel something, like in dreams, I always see people, loads of people, people that I see in the hospital..."
Familiar character from a film (1.5 millamps, left amygdala)
Ill-defined, unpleasant vision (1.5 milliamps, left hippocampus)
Familiar vision that he is unable to describe (1.5 milliamps, left parahippocampal gyrus)
Vision of a familiar person (1.5 milliamps, left parahippocampal gyrus)
Recent scene (1.5 milliamps, right hippocampus) - "I see myself playing the drums, with people from my family listening to me"
The technique of electrically stimulating the brain to trigger certain experiences was pioneered by Canadian neurosurgeon Wilder Penfield and there's an excellent account of his life and work on Neurophilosophy if you'd like some background.
This new study is open-access and completely fascinating, so is definitely worth a read.
Link to 'The dreamy state: hallucinations of autobiographic memory evoked by temporal lobe stimulations and seizures'.
The British Medical Journal has just published one of the greatest and funniest research articles ever to grace the pages of the medical literature with a paper on the potential neurological consequences of headbanging to heavy metal.
As someone who once caused himself concussion and several hours of puking from head banging to Metallica at the age of 14, I feel this is important and invaluable research.
The researchers, Australian rockers Declan Patton and Andrew McIntosh, attended a number of heavy metal concerts to observe the most common forms of headbanging (the 'up-down style' apparently), and then did a biomechanical analysis to estimate the forces operating on the head and brain.
They also convened a focus group of local rockers to list their favourite headbanging classics, and modelled the physical stresses based on the tempo of the tracks.
They discovered that headbanging to songs with a tempo above 146 beats per minute when the head motion was more than 75 degrees was the point at which brain injury was likely to occur.
It's traditional that the Christmas edition of the BMJ has a more light-hearted article. This study is a little different in that the science is completely bona fide, but the scientific paper is a very funny read.
Their public health recommendations are a particular gem:
Though exposure to head banging is enormous, opportunities are present to control this risk—for example, encouraging bands such as AC/DC to play songs like "Moon River" as a substitute for "Highway to Hell"; public awareness campaigns with influential and youth focused musicians, such as Sir Cliff Richard; labelling of music packaging with anti-head banging warnings, like the strategies used with cigarettes; training; and personal protective equipment.
Great article, fantastic title, and completely open access.
Rock on!
Link to 'Head and neck injury risks in heavy metal'.
I've just found this fascinating article on how legendary neurologist Gordon Holmes discovered how the visual cortex represents visual space after studying World War One soldiers who had experienced bullet or shrapnel wounds to the brain.
World War One taught us a great deal about neuropsychology largely due to developments in weapons technology. The German Mauser was an accurate rifle that used small bore ammunition where previous conflicts had largely used single shot rifles mostly designed so a group of soldiers could create a 'wall of lead', rather than a carefully aimed shot.
Developments in shell technology also meant that high explosives could be launched with reasonable accuracy into groups of soldiers causing significant shrapnel injuries.
However, both the rifles and shells were at a stage where the velocity of either a bullet or a piece of shrapnel was relatively slow by today's standards, meaning that the brain was not additionally damaged by shock waves, like with modern munitions.
In other words, they could create small discrete areas of brain damage that left the rest of the brain largely unaffected.
The British Brodie helmet, which sat like a tin bowl on the top of the head, left the lower parts of the head, and hence the brain, exposed. This meant a significant number of injuries were to the visual cortex, at the rear of the brain.
Neurologist Gordon Holmes studied the link between small lesions to this area and which areas of vision had been lost in soldiers coming back from the front.
The diagram on the right is one of his drawings where he demonstrated the link between a very specific shrapnel wound and a crescent-like area of blindness in the visual field. The full diagram is in the article where he also shows how it affected the right eye.
These studies taught us that the visual cortex is 'retinoptically mapped', meaning that each part of the cortex corresponds to a specific area of vision. It also taught us that some brain areas can be very specifically localised to certain functions, whereas previously we'd only known of very general connections between function and brain area.
The article, published in opthamology journal Documenta Ophthalmologica, describes Holmes' wartime experiences, his discoveries and something of his character.
It also contains this curious episode, related by one of his junior doctors, largely notable for the fact that they hid a blonde beauty queen in a bathroom on the hospital ward to boost morale of the medical house officers.
Holmes had no time for neurotics and hysterics, and less ... for psychoanalysis ... [Once] In the ward there was a blonde bombshell of twenty-one with mild tension headaches. She was as pretty as a picture, plump as a partridge, who the previous year had been the Daily Mirror Bathing Beauty Queen. The first time I took Holmes around, he stopped at the foot of the bed and said 'Who is this woman?' I explained, whereupon he jerked his thumb towards the door and said 'Get rid of her'.
Of course, I did nothing of the sort, for she was useful in keeping up the morale of us house officers. A week later he came around and said 'I thought I told you to get that woman out of here?' Yet another week passed. On this occasion I got the Sister of the ward to hide the patient in the bathroom during the ward round. Standing at the foot of the empty bed, Holmes paused, then said to me 'Look here, my boy, either she leaves the hospital or you do - and I don't care which.
Link to 'Gordon Holmes, the cortical retina, and the wounds of war'. Link to DOI for same.
Discover magazine has a thought-provoking article on the question of whether 'shaken baby syndrome', claimed to be a specific type of brain damage that occurs to young children if shaken, actually exists as a useful syndrome. If it doesn't, it might not only be a medical miscategorisation but also a legal disaster that may have falsely convicted innocent families of child abuse.
Critics argue it's a bit like calling a broken nose 'punched in the face syndrome'. The label is for a non-specific injury but which automatically leads us to assume that an aggressor must exist.
Once a doctor says that an infant must have been shaken, it triggers a hunt for the shaker. In one diagnostic step, the legal system is brought to bear on the baby’s family and anyone else near the infant at the time of the supposed shaking.
The symptomatic triad of bleeding between the brain and skull (known as subdural or subarachnoid hematomas), bleeding behind the retinas, and brain swelling is both the core of an SBS diagnosis and the point of departure for the syndrome’s skeptics. The medical proof that shaking alone can cause these internal head injuries is questionable, the skeptics say, when many other things, from infections to malnutrition to falls onto a hard surface, are known to be causes of similar symptoms in infants.
In contrast, supporters of the condition, which came to world-wide attention in the case of British nanny Louise Woodward, argue that shaking causes babies specific injuries that are unlikely to be triggered by anything else. The article quotes Eli Newberger, an assistant professor of pediatrics at Harvard Medical School:
“By the time I was asked to testify in the Louise Woodward case...there was a great deal of clinical understanding about [SBS-related] trauma,” Newberger says. “The infant’s head is disproportionately larger in relation to the rest of its body than our heads are. A child can’t stop the to-and-fro excursions of the head with its neck. The brain bobbles about. The infant’s brain is softer than the adult’s.”...
Money, Newberger suspects, has brought otherwise good people over to what he and his colleagues call the “dark side,” doubting SBS. “I have never ceased to be amazed about what highly regarded, well published, scientifically informed doctors will do when they’re offered large amounts of money,” he says.
And indeed, experts on both sides seem to charge a great deal for their time.
The article walks us through some of the studies that have attempted to look at how many children with these symptoms show other signs of abuse, or have tried to simulate the damage with computer or physical models.
It's a fascinating look at a syndrome I just took for granted as being widely validated and looks at the implications of the scientific work for the legal system, where incorrect diagnosis can lead to abusers going free or loving parents being jailed.
Link to 'Does Shaken Baby Syndrome Really Exist?'.
Walking the line: the danger of sinus neurosurgery :
I've just found this gripping article from The Guardian by photojournalist Tom Bible who was diagnosed with a rare and life threatening brain tumour and had an equally rare and life threatening operation to remove it.
The tumour was located in the superior sagittal sinus, one of the major veins that drains blood from the brain.
Operating on it is very dangerous because it is incredibly difficult to stem the bleeding once it's damaged. As the author mentions in this passage, it's so dangerous that the operation needs to be carried out while the patient's heart is stopped:
I now had a challenge: to find a neurosurgeon who was both willing and able to remove my tumour. Dr Thomas recommended two vascular neurosurgeons in the UK. I arranged an appointment with the first one, who subsequently cancelled, saying that it was not the type of operation he would perform. I visited the second neurosurgeon at the National Hospital in London - the leading UK neurosurgery hospital (and one of the most highly rated in the world). He said he had only heard of one of these before. They had had to remove it by resorting to a practice called the 'cardiac standstill'. In this, they stop the patient's heart, drain the blood from the body and reconstruct the tumour-infested sinus area, pump the blood back into the body and kick-start the heart again.
Blimey.
The author eventually had the operation in the US, and gives a compelling description of the process from first symptoms to the extended procedure that eventually also needs the radiation-based gamma knife treatment.
The eternal quest for the cut-and-dry brain injury:
The annual Society for Neuroscience conference is currently underway in Washington DC and Technology Review has a couple of article that reports on some of the highlights.
One piece is particularly interesting as it focuses on the use diffusion tensor imaging (DTI), a type of MRI scan that identifies the white matter nerve pathways in the brain, to detect otherwise undetectable brain damage.
These white matter pathways are like cabling that runs through the brain and in some forms of head injury they can get twisted, pulled or suffer sheering injuries which may not be easily visible on standard MRI scans.
A minority of people who suffer head injury with no detectable injury on standard MRIs will suffer emotion and behaviour disturbance, memory difficulties, diffuse headaches and problems with concentration.
This is sometimes diagnosed as post concussion syndrome and the researchers hope that DTI scans will find that people with these sorts of complaints will be found to have clear white matter disturbance.
Actually, this is one of the oldest debates in head injury and stretches back to the time when soldiers were first returning from the First World War with 'shell shock'.
One of the theories, largely championed by Maudsley psychiatrist Frederick Mott, was that the shock waves from the shells disturbed the brains of the individuals causing microscopic brain damage.
However, it soon became clear that some soldiers who had 'shell shock' had never been near a shell explosion, while others had genuine brain injury but had similar sorts of problems which weren't easily explained by the physical damage they'd endured.
One of the key lessons from this time was that our expectations, beliefs, emotions and interpretation of experiences and injuries contributed as much to the actual symptoms and disability as the physical damage.
Interestingly, similar sorts of problems have been reported in soldiers returned from Iraq and, as echoed in the TechReview article, there is a big push to clearly separate cases of 'genuine brain injury' from 'emotional trauma'.
History tells us that attempting a clear separation is likely to be futile, because the same symptoms can be produced by either one, or a combination, and knowing that one definitely plays a part doesn't rule out the other.
So it's interesting to hear the people quoted in the article suggest that DTI imaging could help assess who is cognitively able or not, who has a 'real injury or is faking', or whether someone should be sent back to the battlefield, because it relies on a cut-and-dry distinction between 'brain injury' and 'psychological problem' which doesn't exist in the real world.
As an aside, white matter isn't invisible on MRI or CT scans, as suggested in the article, although some white matter injuries might be.
And if you're still hungry for more SfN news, TechReview has another bulletin with several highlights.
Link to article 'Detecting Subtle Brain Injuries'. Link to latest SfN brain research write-up.
BBC Radio 4's excellent discussion programme In Our Time just had an interesting edition on neuroscience - what it does, how it does it, and what it's telling us about the function of the mind and brain.
It's generally a very interesting discussion, although does get a bit confused towards the end during a discussion of conscious - largely due to a misunderstanding of a famous study.
The discussion touches on neuroscientist Adrian Owen's study where they wanted to find out whether a patient in a persistent vegetative state (PVS) was conscious by asking them to imagine things and then using fMRI to see if the relevant parts of the brain were active - in other words, if the person was able to consciously hear, understand and carry out the request.
Famously, the patient could - demonstrating that it is possible to be diagnosed with PVS and still be conscious.
However, the guests on the programme discuss the study as if the patient was unconscious and was in a coma, and suggest that this shows the brain can do remarkable things when someone is unconscious which is exactly what it didn't show.
Otherwise, a fascinating discussion as we'd expect from In Our Time.
Neurophilosophy has recently published two excellent articles that discuss the recent discovery of very selective psychological problems: one person can't recognise people by their voice, the other can't navigate through streets.
In themselves, these sorts of disorders are not that surprising, but they help us understand how the brain develops.
Actually, scratch that last sentence. If you're familiar with the brain injury literature, these sorts of disorders are not that surprising, but if you're not, they're completely mind blowing.
Take prosopagnosia for example. Sometimes rather inaccurately called 'face blindness' (people see faces, they just don't seem distinctive) it was first identified in a patient with a bullet wound to the head who lost the ability to recognise faces but could still recognise other objects.
If you think about it, this is incredible. When we look out onto the world, faces don't seem different from the rest of the things we look at, but damage to a specific area of the brain (most commonly the right fusiform gyrus) can selectively damage our ability to see faces, suggesting that there are brain functions specialised for this task. How specialised, whether only for faces, is a matter of ongoing debate, but the fact that they are specialised at all is incredible enough.
The explanation for these selective impairments goes something like this: our brain functions are shaped by a combination of the broad outline of genetics and the fine tuning of experience during growth. When we reach adulthood they are fairly fixed. Damaged can knock out these fairly fixed pathways leading to selective impairments.
What has become clear over the last decade is that some people can have selective impairments without suffering brain injury. They seem to have them from birth.
This is the case with the two people discussed by Neurophilosophy. An inability to recognise people by just their voice or an inability to navigate streets after brain damage is interesting but not earth shattering. These sorts of cases have been reported before.
But the fact that these are developmental disorders is an interesting and important twist, not least for what they suggest about how much certain functions might be 'set' in the brain early on, but also for what they suggest about the 'life history' or our cognitive skills.
The two case studies discussed by Neurophilosophy are both fascinating as life stories of people with atypical difficulties but also scientifically compelling because they help us understand complex dance of brain growth and development.
Link to piece on developmental topographagnosia. Link to piece on developmental phonagnosia.
Scientific American Mind's Mind Matters blog has a great interview with neuroanthropologist Daniel Lende who discusses why we need an understanding of both culture and neuroscience to get a fully integrated account of human thought and behaviour.
Lende discusses his work on integrating cultural factors and the neuroscience of the dopamine reward system in a study of addiction in Colombian teenagers.
A common approach in neuroscience is to take experiences labelled by everyday words and try and find what changes in the brain when someone says they are having the experience.
The problem is that the definitions of the labelling words may be indistinct ('love'), incoherent ('belief') or understood differently in different cultures ('anxiety').
The approach Lende advocates is to take an anthropological approach to the problem. In other words, attempting to understand what a concept or label means in a particular culture so the neuroscience can be integrated in full knowledge of the diversity of the experience.
This predicament is where neuroanthropology can be so helpful. In order to draw connections between neuroscience and real world situations, I went out and talked to people to understand craving and addiction from their point of view. This type of real-world data can both challenge and inform ideas based on animal models and neuroimaging studies.
In translating the dopamine research, my work with adolescents proved crucial. They knew what they experienced far better than I did. Using systematic interviews across a range of involvement with drugs (hard-core users to having never tried drugs), I saw three areas of overlap between research on dopamine and compulsive involvement with addictive substances.
First was the emphasis that researchers placed on “wanting.” I was lucky in Colombia; addicted adolescents often described their experiences as “querer más y más,” to want more and more. Second, dopamine affects shifts in attention, which meant that some adolescents couldn’t focus on anything else when they knew an opportunity to consume was about to come along. Third, adolescents described a sense of being pushed toward something—an urge that rose up without conscious desire.
You may recognise Lende from the excellent Neuroanthropologyblog and he also discusses some of the work of his co-bloggers in the interview, including some fascinating work looking on how people learn balance.
However, if you're interested in more details about the study on Colombian teenagers, he's recently posted some moreinformation including links to the full text of the papers.
Link to SciAmMind Mind Matters interview. Link to Neuroanthropology post on Colombia study. Link to follow-up and more information.
I've just found another curious case report of complex movements in a brain dead patient, following on from our recent piece on the Lazurus Sign.
These reports are fascinating and bizarre in equal measure, not least when you try and imagine what was happening in the room at the time.
Uncommon reflex automatisms after brain death
Rev Neurol (Paris). 1995 Oct;151(10):586-8.
Awada A.
Two cases of unusual complex movements observed in brain dead patients are described. Rapid and sustained flexion of the neck induced slow abduction of the arms with flexion of the elbows, wrists and fingers over 5 to 10 seconds. These movements have been rarely described and although they have similar clinical patterns, they are pathophysiologically different from the Lazarus sign which is observed few minutes after respiratory support cessation. While Lazarus sign is supposed to be due to an agonal discharge of anoxic spinal neurons, the movements described in this article result probably from complex reflexes generated in a disinhibited spinal cord. It is however surprising that they have never been described in patients with high cervical spinal injuries.
For those of you not familiar with the medical terms for movement, I shall briefly translate. When the doctors rocked the dead person's head side to side forward in a 'rapid and sustained' fashion, the body extended its arms to the side and waved them about.
I have two thoughts.
Firstly, isn't it fascinating that such complex movements can be triggered solely by the spinal cord?
Secondly, what the bloody hell were they doing with that dead body?
Normally, these reports are of spontaneous movements in isolated brain dead patients, but on this occasion the medical team seem to have been rather more involved.
Unfortunately, the full text of the article is in French, so the exact turn of events (e.g. "hey looks what happens when I do this!") shall have to remain a mystery.
UPDATE: Neuroshrink has added a fantastic correction and comment to this post that suggests what might have been happening and recounts his own experience of observing the Lazurus sign.
Link to PubMed entry for article. Link to Mind Hacks on the Lazurus Sign. Link to another Mind Hacks article on the moving dead.
Tim Harford, who blogs as the Undercover Economist, presents a rollercoaster ride through the field of neuroeconomics, for Radio 4. The documentary is available via Radio 4's Listen Again site for the next week, and reportedly via a podcast (which I unfortunately can't find). This whistle-stop tour covers neuromarketing, behavioural economics and the possible effects of hormone levels on risk tasking among stockmarket brokers. The programme features great interviews with some top researchers, such as Paul Glimcher and, Glimcher aside, many of these researchers have an almost relgious optimism about the potential for fMRI-scanning, believing it will eventually tell us how economic decisions are made, why we follow crowds, what we're thinking at any point in time, what age we should be able to vote and how much we value things like clean air. Admist this heady atmosphere the psychologist Gerd Gigerenzer brings us back to earth again: "You can't read the mind. We understand quite little about the brain." he begins. And then,
A former chairman of the Harvard Psychology deptartment once asked me "Gerd, do you know why they love those pictures [the fMRI activity maps]? It is because they are like women: they are beautiful, they are expensive and you don't understand them"
If you read a classical article on neuroeconomics what you will find is mostly results which have been already known and recycled, and very little new insight.
ABC Radio National's All in the Mind recently had an excellent programme on amphetamine, discussing its varying uses from its original selling point as a widely abused nasal decongestant to its modern popularity as a kiddie behavioural control agent in the age of methylphenidate (Ritalin).
One of the most fascinating parts is where the guest, history of science professor Nicolas Rasmussen, discusses how after amphetamine was discovered in the 1930s the drug companies desperately tried to find an illness which it could be prescribed for.
Smith, Kline & French wanted to find a big market and so they looked at common diseases that you know might plausibly be treated by an adrenaline derivative and they tried it out on a huge range of conditions. Menstrual cramps, bed wetting, you name it -- it turns out actually to work for bed wetting if you give it to little kids who have that problem, probably by making them sleep shallower -- but also in psychiatry for depression, and that's what really caught on.
They tried it for an enormous range of conditions through medical experts and the clinical trials where the drug didn't work out well weren't published, because that was already the arrangement then, when a drug company funded a trial unless it fit their marketing needs the results wouldn't be published.
Great to see the spirit of the 1930s is still with us today.
The programme also discusses how the subculture use of the drug interacted with its 'official' uses in the mind of the public and policy makers to give speed the image it has today.
It seems the programme is based on a new book by Rasmussen called On Speed and I love the link at the bottom of the book's website which says 'Purchase On Speed'. I've drunk a lot of coffee. Will that do?
If you're interested in a book on the science of amphetamines, Leslie Iverson's bookSpeed, Ecstasy, Ritalin is simply wonderful and just so much fun to read, as I noted in an enthusiastic review last year.
The AITM programme is a fantastic introduction to the fascinating story of amphetamine, so a great place to begin.
Link to 'Wakey Wakey! The many lives of amphetamine'.
Occasionally, brain-dead patients make movements, owing to the fact that the spinal reflexes are still intact. The most complex, and presumably the most terrifying, is called the Lazarus Sign. It is where the brain-dead patient extends their arms and crosses them over their chest - Egyptian mummy style.
About 20% to 40% of brain dead patients can show spontaneous movements particularly when the body is pricked with sharp objects.
While these movements are usually brief twitches, occasionally the movements can be in an extended sequence, as reported in this 1992 Journal of Neurosurgerycase study about a 67-year-old lady who died from a brain haemorrhage.
At 11:15 am on February 20, brain death was declared and consent for final respirator removal was obtained from the patient's family. The possibility of the appearance of Lazarus' sign was explained to the family, and a video recording was made.
Five minutes after respirator removal, respiratory-like movements occurred three times; both shoulders adducted and slow cough like movements were identified. Lazarus' sign immediately followed these respiratory-like movements. The forearms were pronated and the wrist joints extended bilaterally. Fingers on the left hand were extended, but those on the right were flexed as if grasping. Subsequently, flexion and extension in the knee and foot joints were repeatedly observed. Slow supination of both feet occurred. Finally, the left forearm was adducted to the side of the body, and the right hand pronated.
The movements continued for about 3.5 minutes, during which time blood pressure was 46/35 mm Hg and pulse rate was about 90 beats/min with a regular sinus rhythm. Cardiac arrest occurred at 11:35 am.
Link to PubMed entry for case study. Link to brief popular article on Lazarus sign.
Seed Magazine has got video of a great talk by Henry Markham, the director of the Blue Brain Project which is developing the world's largest simulation of networks of individual neurons in an attempt to understand the large scale dynamics of the brain.
Their ambition is to be able to run a simulation on the scale of the whole human brain within a decade.
If you want a good summary of where the ambitious project is at, Seed recently had an excellent Jonah Lehrer piece on the research that we featured earlier this year.
Markham's talk is interesting not solely for his take on the project and its aims, but also for the fantastic visualisation he uses to illustrate what it's doing.
Surely this must be the greatest headline for a BBC Newsstory ever: Banjo Used in Brain Surgery.
Although the banjo wasn't in the hands of the surgeons it was still an essential part of the operation. It was played by legendary Blue Grass musician Eddie Adcock who was having surgery to install a deep brain stimulation device to treat an essential tremor that had been affecting his playing.
The BBC News story has a video of the neurosurgery and the banjo playing, and it is pure genius. Probably the best thing you'll see all year.
Essential tremor is a condition where there is a continuing deterioration in areas of the brain that control movement. This causes a tremor that usually appears when the person tries to act or move, although can lead to a 'resting tremor' that's also present at other times.
Essential tremor is not Parkinson's disease, which, while also associated with tremor, is a much more serious and disabling condition in many ways. There does seem to be a link though, as people with essential tremor are more likely to develop Parkinson's, although this still only happens in the minority of cases.
However, deep brain stimulation can be used to treat the movement difficulties of both Parkinson's and essential tremor. It involves sinking an electrode into the thalamus, a deep brain area that is part of the motor loop - a circuit that helps co-ordinate movement.
In fact, there are two parts to the motor loop - the direct and indirect pathway - an each play a complementary part in directing movement, and each of which needs to be balanced with itself and with each other. When damage to these circuits affects this balance, the result is that it causes too much activity one way, which causes a compensatory response the other, and so on.
Imagine two people, completely unaware of each other, trying to balance an uneven seesaw. The oscillations in the control system cause oscillations in movement, and this is what you can see in tremor.
DBS works by sending electrical impulses at a certain frequency into the thalamus to dampen down the oscillations. However, the oscillatory push-push cycle is not the same for everyone, and the best spot in the motor loop itself will also differ.
To get the best result the surgeons tweak the electrical pulse settings and try different areas.
To make sure it's having the desired effect, the patient is awake and they ask them to move. When they see that they've hit the sweet spot and the pulses are in time, they know their job is done.
One of Eddie Adcock's impairments is that he has tremor, but the main impact on his life is that it affects his banjo playing. So the most sensible thing to do is to tweak the system while he's playing the banjo to optimise the effect for the thing that's most important to him.
And that's why a banjo was used in brain surgery.
Link to BBC video of 'Banjo Used in Brain Surgery'.
I just came across these two beautiful images in a paper by neuroscientist Marek Kubicki and colleagues on diffusion tensor imaging studies in schizophrenia.
DTI is a technique that using MRI scans to track how water moves throughout the brain. As water tends to move in one particular direction when its trapped inside nerve fibres, a technique called MRI tractography can be used to map out all the white matter 'cabling', separate from the rest of the brain.
I think the technique produces some of the most beautiful images in neuroscience. You get to see the brain's connections, disconnected, and suspended in space.
Link to full-text of paper (see page 27 for images). Link to PubMed entry for same. Link to more DTI tractography images.
The San Francisco Chronicle has a great article about Dr Charles Cobbs, a neurosurgeon who had the seemingly wacky idea that malignant brain tumours called gliomas might be caused by a viral infection. Initially dismissed, there is now growing evidence for his idea and how it might lead to better prevention and treatment for these usually fatal forms of brain cancer.
Gliomas are tumour that form from glial cells - non-neuronal brain cells that provide support, nutrition protection and some just-recognised roles in signalling.
As you might expect, they are an essential part of almost every part the brain and a malignant tumour which grows from glial cells can be fatal (without treatment, within about 3 months) as they are very difficult to remove and treat.
Cobbs had observed that his patients diagnosed with malignant glioma - an aggressive brain cancer that leaves victims with a two-year life expectancy - were mostly older, well-educated and from higher socioeconomic backgrounds. Their "hyper-hygienic" lifestyles had possibly left their immune systems susceptible to more common viruses, such as the human cytomegalovirus, or CMV, a herpes virus so ubiquitous that it infects 4 of 5 Americans.
During off-hours, and without formal research funding, Cobbs and a lab partner analyzed dozens of brain tumor samples: All of them were riddled with CMV. In 2002, the doctor published his novel finding in a leading medical journal Cancer Research where it was quickly dismissed by many of his peers. "I was left with a lot of self doubt," said Cobbs, now 45. "My fear was that we'd done something incorrect. But now, my confidence is growing."
In February, brain cancer researchers at Duke University Medical Center published the first peer-reviewed report that confirmed Cobbs' discovery, followed by two reports from independent labs at the M.D. Anderson Cancer Center at University of Texas in Houston and the Karolinska Institute in Stockholm, Sweden. And this month, the National Brain Tumor Society is sponsoring a first-of-its-kind gathering in Boston of the world's top virologists and glioma experts to examine the possible link between CMV and the deadly brain tumors that are diagnosed in 10,000 Americans every year.
The photos accompanying the piece are excellent by the way. The image I've used to illustrate this post is particularly impressive - click on it to see the full-size version which you need to get the full effect.
Nature also ran a piece about Cobbs last month owing to the publication of one of his studies in the same issue where he discovered one of key receptors on which the CMV virus has its action.
Unfortunately, I can't read either as Nature's Athens login system is currently broken [insert your own rant about open-access publishing here].
Link to SFChronicle article 'Surgeon changes study of brain tumors'.
A list of things that deep brain stimulation has been used to treat. DBS involves surgically implanting an electrode into the brain which is stimulated with a 'pacemaker' like device.
I've just been looking over the DBS literature and I was quite surprised to see that it has been used to try and treat just about anything you can think of.
Maybe someone should try it for over-optimistic repetitive surgery syndrome? Anyway, here's the one's I've found, if you know of any others, do send them in or add them to the comments.
This is quite a remarkable study from a 1985 edition of the International Journal of Neuroscience that investigated whether the apparent greater use of mental imagery during masturbation by men than women was due to differences in hemispheric specialisation.
To test whether this might be to do with brain organisation, rather than gender itself, the researchers tested the idea by asking about imagery during masturbation in right-handed males, who typically show strong hemispheric specialisation, and left-handed men, who typically show less specialisation.
Unfortunately, I don't have access to the full paper and have no idea whether the claim that women typically report less imagery and fantasy is still thought reliable, as these sorts of findings are notoriously influenced by how the question is asked.
However, the study seemed to find partial support for it's own hypothesis at least.
Sex and handedness differences in the use of autoerotic fantasy and imagery: a proposed explanation.
Int J Neurosci. 1985 May;26(3-4):259-68.
Gottlieb JF.
Previous research has described a greater use of fantasy and imagery during masturbation by men, than women. This study suggests that this gender disparity results from the increased frequency of bilateral speech representation found in the female brain. Support for this theory was obtained by comparing the use of autoerotic fantasy and imagery in another group distinguished by their degree of cerebral lateralization: dextral vs. sinistral males. The prediction that masturbatory fantasy and imagery would be more common in the more lateralized dextral males was partially confirmed in this study.
I gave up looking for a suggestive yet tasteful image than combined the concepts of sex and hemispheric specialisation, so I've illustrated this post with picture of a flower instead.
As an aside, brain anatomy has a few rude jokes thrown in. For example, the mammillary bodies are two small round areas that are part of the limbic system. Their name comes from the fact that the look like breasts.
I was told by a neuroanatomy lecturer that one of the reasons given for why women shouldn't study medicine in the 1900s was because they'd be offended by the blue humour.
However, the tradition has continued and there are many bawdy mnemonics that help modern students of the nervous system learn the names and functions of the cranial nerves.
Link to PubMed entry for hemispheric fantasy study.
KQED Quest has another excellent online feature where they discuss the curious effect where some patients with fronto-temporal dementia, a form of degenerative brain disease, suddenly have burst of creative talent creating some stunning and original works.
The videos were taken at UCSF over the course of many hours doctors spent studying Keith and his symptoms. In them, we glimpse of two of Keith’s FTD-caused obsessions: joke telling and music. (We also see one of the first symptoms to have emerged: his Jerry Garcia hairdo.)
At first glance, Keith’s behavior might strike you as more eccentric than brain-damaged, which is precisely why FTD can take so long to diagnose. If you’re a doctor with a 15-minute appointment slot, frontotemporal dementia might just look like a midlife crisis...
FTD can turn Democrats into Republicans, and vice versa. People with no interest in art begin to paint obsessively. As the neurons in Keith’s right frontotemporal lobe (just behind the right eyebrow) died, his taste in music, his sense of humor, his relationships with his family members and friends changed completely. Our self, in other words, may owe much more to the way our brains are built than we’d care to acknowledge.
It's probably worth making clear that this is quite a rare effect. Most people with FTD will not become artistically inspired.
More common effects are problems with inhibiting behaviour sometimes leading to problems with appropriate social interaction (largely owing to frontal lobe damage) and difficulties with language and meaning (largely owing to the problems with the temporal lobes).
But because dementia trends to affect the brain in a progressive but patchy way, it can sometimes result quite unusual or surprising symptoms.
The Quest programme is a radio show, a video of Keith Jordan - a patient affected by FTD, and a narrated photo essay.
Another great production from Quest, who we featured recently because of their similarly high-quality programme on the curious pseudobulbar affect.
If you're interested in more information on the release of artistic talents after FTD, we featured a fantastic New York Timesarticle on the same topic which makes a great complement to the Quest programme.
Link to Quest radio programme. Link to Quest video section. Link to Quest narrated photo essay.
A 48-year-old woman with a stimulating electrode implanted in her right ventral thalamus started to compulsively self-stimulate when she discovered that it could produce erotic sensations.
This is a report from the early days of deep brain stimulation, way back in 1986, from an article for the medical journal Pain which discussed some unintended side-effects from one patient's DBS treatment for chronic pain.
Soon after insertion of the nVPL electrode, the patient noted that stimulation also produced erotic sensations. This pleasurable response was heightened by continuous stimulation at 75% maximal amplitude, frequently augmented by short bursts at maximal amplitude. Though sexual arousal was prominent, no orgasm occurred with these brief increases in stimulation intensity. Despite several episodes of paroxysmal atrial tachycardia [heart disturbance] and development of adverse behavioural and neurological symptoms during maximal stimulation, compulsive use of the stimulator developed.
At its most frequent, the patient self-stimulated throughout the day, neglecting personal hygiene and family commitments. A chronic ulceration developed at the tip of the finger used to adjust the amplitude dial and she frequently tampered with the device in an effort to increase the stimulation amplitude. At times, she implored her to limit her access to the stimulator, each time demanding its return after a short hiatus. During the past two years, compulsive use has become associated with frequent attacks of anxiety, depersonalization, periods of psychogenic polydipsia and virtually complete inactivity.
Similar cases are still being reported today. A 2005 case report described a gentleman who had a DBS electrode inserted into the right subthalamic nucleus to treat the symptoms of Parkinson's disease. He found that switching the device on and off produced a 'morphine like' sensation that he became quite fond of.
This effect was first discovered in humans in the early 1960s, when controversial psychiatrist Robert Heath reported on two cases of people with a number of electrodes implanted in the brain, including some in similar areas to the patients mentioned above.
In 1972, he undertook a notorious study where he implanted electrodes into the brain of a consenting 24-year-old gay male who had been repeatedly hospitalized for chronic suicidal depression and found to have temporal lobe epilepsy.
The brain implant was specifically introduced for non-sexual reasons but Heath decided to test whether pleasurable brain stimulation would encourage the man, known only as B-19, to engage in heterosexual sexual activity with a prostitute.
The study was a 'success' but has become infamous as one of the more distasteful episodes in the history of 'gay conversion therapy', which is quite hard going in a field that is well-known for its distasteful episodes.
Heath was apparently funded by the CIA as part of their abortive research programme into 'mind control' techniques, but I can't find any reliable reference for that, so it might need to be taken with a pinch of salt.
Link to paper 'Chronic Thalamic Self-Stimulation'. Link to PubMed entry for paper. Link to Heath 'gay brain stimulation' study. Link to doi link for same.
ABC Radio National's All in the Mind recently broadcast a gripping programme on patients in the coma-like persistent vegetative state (PVS) and how new brain imaging techniques might be able to identify people who are conscious but unable to communicate with the outside world.
The programme talks to neuropsychologist Adrian Owen, whose work we've featured previously on Mind Hacks, who conducted a brain imaging study on a 23-year-old woman in PVS suggested that she could understand what was being said to her.
The neuroimaging team asked her to practice mental tasks when and could pick up and distinguish the related brain activity using an fMRI scanner.
The programme discusses Owen and colleagues research, including a peak at some ongoing studies to try and turn this into a method of communication, and debates the ethics of dealing with patients who are effectively unresponsive to the world.
It's also got some striking excerpts from a Kate Cole-Adams' novelWalking to the Moon about a woman who emerges from coma. If you want to hear more, another ABC show interviewed Cole-Adams and discussed the book.
Link to AITM on 'Beyond coma'. Link to Life Matters on 'Walking to the Moon'.
Lawrence of Arabia is dead, long live the crash helmet:
I just found this fascinating article from a 2002 edition of Neurosurgery that tells how a brain surgeon who unsuccesfully operated on Lawrence of Arabia after his fatal motorcyle crash was inspired to research and design crash helmets that now save thousands of lives.
T.E. Lawrence, better known as Lawrence of Arabia, was a hero of the First World War who worked as a covert agent leading a revolt against the Ottoman Empire in the Middle East and was immortalised in the 1962 film.
Lawrence was also a fan of motorbikes. In fact, he's pictured on one in the image on the left. Sadly, his interest eventually led to his death after a motorcycle crash in Dorset.
The Neurosurgery article tells the story of Hugh Cairns, a young neurosurgeon who attempted unsuccessfully to save Lawrence's life as part of the surgical team who treated him.
His experience led him to research the benefits of early crash helmets on Army motorcycle riders during the Second World War, finding that they were one of the major life-saving factors.
He later went on to use his knowledge of how the brain becomes damaged during impact to design and test various types of crash helmet that could best protect against these forms of injury.
Cairns' work was a major influence on both the legal system, that has mandated helmets in many countries, and the design of the headgear itself - preventing thousands of fatal brain injuries in the process.
Link to article on Lawrence, Cairns and the origin of crash helmets. Link to PubMed entry for article.
The Boston Globe has an interesting piece on daydreaming, touching on the link between daydreaming and creativity and discussing the possibly brain networks that might support our pleasant mental wanderings.
The article discusses some of the recent work on the default brain network and how this might be related to daydreaming:
Every time we slip effortlessly into a daydream, a distinct pattern of brain areas is activated, which is known as the default network. Studies show that this network is most engaged when people are performing tasks that require little conscious attention, such as routine driving on the highway or reading a tedious text. Although such mental trances are often seen as a sign of lethargy - we are staring haplessly into space - the cortex is actually very active during this default state, as numerous brain regions interact. Instead of responding to the outside world, the brain starts to contemplate its internal landscape. This is when new and creative connections are made between seemingly unrelated ideas.
"When you don't use a muscle, that muscle really isn't doing much of anything," says Dr. Marcus Raichle, a neurologist and radiologist at Washington University who was one of the first scientists to locate the default network in the brain. "But when your brain is supposedly doing nothing and daydreaming, it's really doing a tremendous amount. We call it the 'resting state,' but the brain isn't resting at all."
It's worth bearing in mind that the connection between this network and daydreaming is only one theory, and other researchers think of it quite differently.
The 'default network' was suggested owing to measurements of how the brain uses energy at rest, and when brain imaging researchers noted that certain parts of the brain (mainly midline areas) were more active when participants didn't seem to be doing very much but showed reduced activity when we participants were most engaged in attention-demanding tasks.
Neurologist Marcus Raichle has been most vocal in proposing that the network is linked to what we might broadly call daydreaming, mostly notably on the basis of a study that found that default network activity was related to what they called 'stimulus independent thought'.
They determined this by training people on a memory task until they could do it so easily their minds wandered. They then put people in a scanner, compared brain activation in this condition to brain activation with a similar memory task but where the material was new, so they had to concentrate and weren't able to think about other stuff.
They found that the practised condition was associated with activity in a default network, and, therefore, they linked it to daydreaming.
The trouble is, is that they only confirmed that participants were doing more off topic thinking, not what they were thinking about.
We might think of daydreaming as having thoughts about being the lead singer of an all-girl skiffle band, fighting a dragon if it happened to burst through the lab door, or screwing the research assistant who took us through the consent form, but it could be that the participants were just focused on the other stuff that was happening around them at the time.
Like the horrendous noise of the fMRI scanner, as some commentators suggested. Or perhaps, they were just being more aware of their wider environment.
And in fact, one theory suggests that the default network is not concerned with daydreaming, but maintains a background level of watchful attention to detect potentially dangerous external events (real dragons, for example), or perhaps processes memories - essentially doing our mental filekeeping.
One big problem with this area, is that it attempts to study a network which is supposedly most active when when not doing deliberate mental tasks, by extrapolating from data that involves the participants doing deliberate mental tasks.
This makes it difficult to tie it specifically to daydreaming, which is a subjective mental state that has a tendency of dancing away whenever we try and catch it.
Wikipedia has a short but fascinating page listing animals by the number of neurons they have. There's only about a dozen entries on there, but most interesting is that there is an animal with no nerve cells at all.
It's called Trichoplax and apparently is a "a simple balloon-like marine animal with a body cavity filled with pressurized fluid".
Apparently humans don't come top of the pile, as both elephants and whales have more neurons.
However, it's not the best referenced article in the world, to say the least, so I'm taking this last claim with a pinch of salt for the time being.
If you know better, do update the article with some more reliable sources.
The BBC has just begun broadcasting a fantastic series called Blood and Guts on the history of surgery with the first episode on neurosurgery. If you live in the UK you can watch it again on the BBC iPlayer for a few days more, or otherwise, it has appeared online as a torrent.
It's not the most coherent trip through the history of neurosurgery, more a collection of highlights (or, in some cases, lowlights), but it's very well made and has some fantastic historical footage and interviews with modern neurosurgeons.
It covers Harvey Cushing, Phineas Gage, José Delgado, Walter Freeman and the frontal lobotomy, transcranial magnetic stimulation, deep brain stimulation and the cutting edge of brain surgery today. There's a particularly interesting bit where lobotomy survivor Howard Dully has a brain scan and you can see the effect of his operation.
If you're still hungry for more, BBC News website has an article and video clip of neurosurgery while the patient is conscious, and you can even buy the book of the series.
Link to BBC iPlayer archive (for 7 days). Link to torrent of Blood and Guts brain surgery episode.
Wired Sciencecovers a recent US military report on military threats from the latest developments in neuroscience as well as how brain research could be 'weaponised' to enhance soldiers' capabilities or disable enemy fighters.
It's a bit difficult to judge the quality of the report, as unlike the recent in-depth report from the JASON Pentagon advisory panel, they're charging people to download it.
From the Wired summary, it seems to cover similar ground although is perhaps a little more wide-ranging and focuses on policy and foresight rather than the nuts and bolts of brain science.
It apparently covers four main areas: mind reading; cognitive enhancement; mind control and brain-machine interfaces. As you can probably tell from the list, there's likely to be a fair amount of speculation going on there.
It's also interesting that the US military are really promoting their 'military neuroscience' angle, which is not to say that it is not a research priority. Whole wings of military research are now devoted to 'human research', as illustrated by the extensive science portfolio of the US Army's Research Lab.
Nevertheless, the discussions about drug-based enhancements have so far been largely reiterating what soldiers have already done for millennia - using drugs to reduce fatigue, increase confidence and cope with trauma.
Drugs have been used for soldiering as long as there have been wars and the low-tech still prevails - from the use of coca leaves by Inca warriors to the use of the khat by modern-day Sudanese militias.
If anyone does happen to stumble across an unrestricted copy of the report online, do let me know as it'd be great to be able to link to the original.
Link to Wired Science article 'Uncle Sam Wants Your Brain'. Link to online shop for report.
I've uploaded a fascinating video clip where a TV presenter is intravenously injected with the active ingredients of cannabis as part of the BBC documentary Should I Smoke Dope?
It's part of an experiment to compare the effects of intravenous THC and cannabidiol combined, with intravenous THC on its own. The mix of both gives the presenter a pleasant giggly high while THC on its own causes her to become desolate and paranoid.
Both are these are known to be key psychoactive ingredients in cannabis but the video is interesting as it is a reflection of the fact that THC has been most linked to an increased risk of developing psychosis while cannabidiol seems to have an antipsychotic effect.
As we discussed earlier this year, one study found that cannabis smokers who had higher levels of cannabidiol in hair samples had the lowest levels of psychosis-like experiences.
Another study we covered reported that, at least in the UK, 'skunk' has virtually no cannabidiol, while hash, although variable, was more likely to contain high cannabidiol levels.
And if you're after a more balanced view on the link between cannabis and psychosis than you normally get in the media, I've also uploaded a clip from the same programme where psychiatrist and leading cannabis researcher Robin Murray discusses the findings from the latest research.
If you want to check out the whole documentary, where BBC reporter Nicky Taylor gets stoned for 30 days in a row while investigating the science, culture and legal status of cannabis, it's available as a torrent or in six parts on YouTube (1, 2, 3, 4, 5, 6).
Link to video of IV cannabidiol and THC experiment. Link to video of psychiatrist Robin Murray on cannabis and psychosis.
Cannabalism gave Western medicine its first understanding of prion diseases as an epidemic of the neurological disorder swept the South Fore tribe in Papua New Guinea. Neurophilosophy has written a remarkably lucid article on the history and neuroscience of how prion diseases, of which 'mad cow disease' is one, affect the brain.
The piece starts with some archive footage of a tribe member with the devastating disorder and continues to describe how this class of diseases are probably caused by misfolded proteins that can trigger the same misfolding in other proteins leading to a chain reaction of neural damage.
The Fore tribe had a tradition of ritually consuming the brain and body of deceased relatives, which likely lead to the outbreak.
The word kuru means "shaking death" in the Fore language, and describes the characteristic symptoms of the disease. Because it affects mainly the cerebellum, a part of the brain involved in the co-ordination of movement, the first symptoms to manifest themselves in those infected with the disease would typically be an unsteady gait and tremors. As the disease progresses, victims become unable to stand or eat, and eventually die between 6-12 months after the symptoms first appear.
Kuru belongs to a class of progressive neurodegenerative diseases called the transmissible spongiform encephalopathies (TSEs), which also includes variant Creutzfeldt-Jakob Disease (vCJD) and bovine spongiform encephalopathy (BSE, more popularly known as "Mad Cow Disease"). TSEs are fatal and infectious; in humans, they are relatively rare, and can arise sporadically, by infection, or because of genetic mutations. They are unusual in that the infectious agent which transmits the diseases is believed to a misfolded protein. (Hence, the TSEs are also referred to as the prion diseases, "prion" being a shortened form of the term "proteinaceous infectious particle").
Prion diseases are a complicated area and you probably won't find a better written introduction that captures both the science and the intrigue of these relatively new disorders.
Link to article 'Cannibalism and the shaking death'.
The best is yet to come: reward prediction in the brain:
Jonah Lehrer has written an excellent piece for the latest issue of Seed Magazine on the work of neuroscientist Read Montague who's been discovering the essential function of dopamine in predicting rewards.
Reward prediction is the process where dopamine neurons fire when a reward is expected and also seem to code the amount of error between the prediction and what actually happens. Importantly, the process seems to be accurately described by an algorithm that was already used in computer science.
This has been an area of intense interest over the last decade as it ties together neurobiology, learning, motivation, mathematics and can be demonstrated in a variety of simple lab-based tasks. The fact that dopamine has been linked to numerous disorders in the past makes it a popular paradigm in which to understand psychiatric symptoms.
The Seed article looks at the work of Read Montague who has been studying the process and has been using ingenious methods to look at the role of this system in social reasoning.
In recent years Montague has shown how this basic computational mechanism is a fundamental feature of the human mind. Consider a paper on the neural foundations of trust, recently published in Science. The experiment was born out of Montague’s frustration with the limitations of conventional fMRI. “The most unrealistic element [of fMRI experiments] is that we could only study the brain by itself,” Montague says. “But when are brains ever by themselves?” And so Montague pioneered a technique known as hyper-scanning, allowing subjects in different fMRI machines to interact in real time. His experiment revolved around a simple economic game in which getting the maximum reward required the strangers to trust one another. However, if one of the players grew especially selfish, he or she could always steal from the pot and erase the tenuous bond of trust. By monitoring the players’ brains, Montague was able to predict whether or not someone would steal money several seconds before the theft actually occurred. The secret was a cortical area known as the caudate nucleus, which closely tracked the payouts from the other player. Montague noticed that whenever the caudate exhibited reduced activity, trust tended to break down.
One thing I notice a little of in the quotes from Montague, which is incredibly common in discussion of dopamine and reward, is a kind of 'reward system dogma'.
Reward is usually linked to the function of the striatum and nucleus accumbens and the dogma goes something like this: "no matter what is happening when the nucleus accumbens or striatum is activated, something about the activity is rewarding".
I was interesting to read a recent study comparing brain activation in people with 'normal' and 'complicated' (i.e. extreme) grief in response to viewing pictures of their deceased relative.
The study found additional nucleus accumbens activation in people with complicated grief and suggested that this reflects the fact they find the thoughts of them more rewarding. This is despite the fact that the nucleus accumbens has also been found to also represent salience - i.e. how likely something is to grab our attention.
It's probably also worth mentioning that there may be some serious problems with the elegant reward prediction theory of dopamine which are were outline in a 2006 paper in Nature Reviews Neuroscience and summarised by the excellent Developing Intelligence.
The Seed is generally an excellent read though and covers an important finding and some innovative new ideas. I especially like the fMRI machines linked in parallel, like multi-player arcade machines.
Neurology journal Brain has just published an elegant open-access study on how just six weeks of mental imagery training can help reduce phantom limb pain as well as reorganising the sensory and motor maps in the brain.
Phantom limbs are when amputees feel sensations that seem to be coming from the missing limb. Sometimes this can include pain which can either be constant or transitory.
Sensations from the nonexistent limb are thought to be due to the brain reorganising the areas which represent the body.
In the case of a phantom arm, for example, the area is no longer receiving sensations from the limb and so stops being so carefully defined. Areas serving other body areas (like the face) start to creep in and facial stimulation can be felt in the missing arm due to the fuzzy neurological boundaries.
This new study, led by neuroscientist Kate McIver, decided to test whether mental imagery can help keep these areas active and prevent the fuzziness creeping in, potentially reducing the phantom pain.
This is based on extensive research to show that imagining something activates similar brain areas to actually perceiving the sensation or executing the action. For example, imagining the sensation of a cool breeze across your arm actually increases activity in the brain areas responsible for arm sensations, while imaging picking something up activates arm-related motor areas.
The research team asked participants to rate their phantom limb pain and used fMRI to look at which brain areas were most active during some movement-related tasks. While in the scanner, the participants were asked to imagine actions with either the existing or phantom hand, to move the existing hand or were asked to purse (push together) their lips.
This last action tends to activate what was previously the hand area in the brain in people with phantom limbs, but doesn't in people with intact limbs. Indeed, this is exactly what the initial brain scans reported, indicating that their brains had reorganised sensory boundaries.
The researchers then invited each participant for six weekly sessions that involved a mental 'body scan' technique that involved imagining free and comfortable movement in their phantom limb such as they could "stretch away the pain" and "allow the fingers, hand and arm to rest in a comfortable position". Participants also practised in their own time.
After six weeks, pain ratings were taken again and the brain scanning was re-run. The painful sensations had significantly reduced and lip pursing no longer activated the hand area.
The mental imagery seemed to have 'simulated' arm actions and sensations well enough so that the neurological boundaries remained sharp and cross-area fuzziness didn't encourage phantom pain.
Link to full text article in Brain. Link to PubMed entry.
Juggling can change brain structure within 7 days:
A new study just published in PLoS One reports that learning to juggle alters the structure of motion detection areas in the brain within as little as 7 days.
Led by neuroscientist Joenna Driemeyer, the study builds on a previous research that also found juggling could alter brain structure, although this previous study waited three months before the brain was checked for alterations using high resolution structural MRI scans.
This new study also took 20 non-jugglers and asked them to learn to juggle, but scanned them after 7, 14 and 35 days.
After only 7 days, a motion specialised part of the occipital lobe known as V5 had increased in density. In both studies, the changes were maintained over the subsequent weeks of practice, but these areas returned to their pre-learning state after several weeks without juggling.
This is an interesting example of rapid 'neuroplasticity', the ability of the brain to adapt structurally to new situations.
However, the authors are careful to note that they can't tell whether the brains of the participants had generated more neurons, or whether existing cells grew in size, or additional glial cells were developed, or maybe there were just changes in how much blood or other brain fluids packed the area.
Also, the fact that changes seemed to occur at the beginning of the learning cycle but that further practice maintained but didn't cause additional changes led the researchers to speculate that learning a variety of new things, rather than simply practising old skills, may be most effective in terms of brain structure alterations.
Link to 'Changes in Gray Matter Induced by Learning — Revisited'. Link to PubMed entry for paper.
Full disclosure: I'm an unpaid member of the PLoS One editorial board.
Scientific American has an article on migraines that takes a comprehensive look at the science of this painful and hallucinatory disorder.
The piece updates the science on migraines from the traditional but oversimplified 'constricted blood vessels' explanation to explore the interplay between nerves, neurotransmitters and lifestyle.
A crucial process seems to be cortical spreading depression that may be responsible, at least in part, for both the intense pain and the aura:
Aura appears to stem from cortical spreading depression—a kind of “brainstorm” anticipated as the cause of migraine in the writings of 19th-century physician Edward Lieving. Although biologist Aristides Leão first reported the phenomenon in animals in 1944, it was experimentally linked to migraine only recently. In more technical terms, cortical spreading depression is a wave of intense nerve cell activity that spreads through an unusually large swath of the cortex (the furrowed, outer layer of the brain), especially the areas that control vision. This hyperexcitable phase is followed by a wave of widespread, and relatively prolonged, neuronal inhibition. During this inhibitory phase, the neurons are in a state of “suspended animation,” during which they cannot be excited.
Neuronal activity is controlled by a carefully synchronized flow of sodium, potassium and calcium ions across the nerve cell membrane through channels and pumps. The pumps keep resting cells high in potassium and low in sodium and calcium. A neuron “fires,” releasing neurotransmitters, when the inward flow of sodium and calcium through opened channels depolarizes the membrane—that is, when the inside of the cell becomes positively charged relative to the outside. Normally, cells then briefly hyperpolarize: they become strongly negative on the inside relative to the outside by allowing potassium ions to rush out. Hyperpolarization closes the sodium and calcium channels and returns the neurons to their resting state soon after firing. But neurons can remain excessively hyperpolarized, or inhibited, for a long time following intense stimulations.
The article is remarkably comprehensive, probably as it's written by neurologists David Dodick and John Gargus.
Link to SciAm article 'Why Migraines Strike' (via 3Q).
Today's Nature has an excellent feature article on the heated scientific debates over why its so hard to link genes to specific mental illnesses.
Genetics is a complex business, but psychiatric genetics even more so, because it attempts to find links between two completely different levels of description.
Genes are defined on the neurobiological level, while psychiatric diagnoses are defined on the phenomenological level - in other words, verbal descriptions of behaviour, or verbal descriptions of what it is like to have certain mental states.
There is no guarantee, and in many people's opinion, probably no likelihood, that these 'what it is like' descriptions actually clearly demarcate distinct processes at the biological level.
It's a bit like classifying people as heavy metal fans if they have five or more heavy metal albums.
By definition, there's a biological difference between people who like heavy metal and those who don't, but it could be a whole number of distinct differences at the level of brain function which are all just recognised as 'being a heavy metal fan' in day-to-day life.
Actually, psychiatric diagnosis has an additional problem, in that for some diagnoses, the same classification can be made when the people don't share any symptoms. For example, two people could be classified as having schizophrenia / being a heavy metal fan, when they have no symptoms / albums in common.
Some psychiatric geneticists just argue that we don't have enough data yet, because it seems that when connecting genes to psychology each gene contributes very little and the effect is when the influence of many small effect genes add up and interact.
Others argue that we should look for effects on 'endophenotypes' - the cognitive building blocks of more complex mental life. So instead of trying to connect genes to a collection of 'what it is like' experiences, we look at how genes influence neuropsychological processes - such as the mechanisms in the prefrontal cortex that control attention.
Increasingly, some researchers are starting to suggest that the genetic results show that existing psychiatric classifications are invalid, and that we should rethink them as new data comes in.
One thing psychiatry has traditionally been very bad at though, is refining diagnoses on the basis of lab studies.
Definitions are often revised to make them statistically more reliable (i.e. so people can reliably agree what is and what isn't a particular diagnosis), but this is not the same as having something which is a good basis for scientific enquiry.
Unfortunately, psychiatry is (ironically) a bit too emotionally attached to the traditional diagnostic categories because diagnosis is such a core part of what psychiatrists do.
Anyway, the Nature piece is an excellent guide to the debate on whether we should be attempting to link genes to the neuropsychology of mental disorder.
Link to article 'Psychiatric genetics: The brains of the family'.
Wired has picked up on a US military report that warns of the threat posed by neuro-enhanced enemy soldiers, just released by the "Pentagon's most prestigious scientific advisory panel".
The full report is available online as a pdf file, and covers how pharmaceuticals and brain-computer interfaces could be used by enemies of the US to create hordes of sleep-resistant super-intelligent neurosoldiers who can kill at the speed of thought.
Obviously, I paraphrase, but it's interesting that the report is not your usual blue-sky speculation. It actually covers the science in considerable detail.
It also discusses cultural attitudes to cognitive and brain enhancements of various sorts, and how this might affect how and why they might be used.
Non-medical applications of the advances of neuroscience research and medical technology also pose the potential for use by adversaries. In this context, we must consider the possibility that uses that we would consider unacceptable could be developed or applied either by a state-adversary, or by less-easily identified terrorist groups. In the following, we consider first the issues of what types of human performance modification might alter a military balance, and how those issues can be evaluated. We then address two broad areas where there are significant, and highly publicized, advances in human performance modification. These are the areas of brain plasticity (permanently changing the function of an individual’s brain, either by training or by pharmaceuticals), and the area of brain-computer interface (augmenting normal performance via an external device directly linked to the nervous system).
In 1941, brain specialist Russell Brain published an article about the brain in the brain science journal Brain. Owing to Brain's extensive work on the brain, he later became editor of Brain. His work treating brain disorders and his editorship of Brain were some of the reasons he was made Baron Brain, in 1962.
Last year, Brain published a tribute to Brain's brain article in Brain, owing to its massive impact on our understanding of the brain.
A fantastic new study which looked at the 'connectedness' of the human brain has identified which aspects of the underlying network are the most important routes of communication.
The research was led by neuroscientist Patric Hagmann and combines brain imaging with network mathematics to not only visualise the brain's network but also to understand which are the most important hubs and connections.
The study used diffusion spectrum imaging or DSI to map out the white matter wiring of the brain in five healthy individuals.
It's a type of diffusion MRI that identifies water molecules and tracks how they move. In a glass of water, water molecules will move randomly, but when trapped inside nerve fibres, they move along the length of the fibre, allowing maps to be created from the average paths of the moving molecules.
The researchers then took the maps of fibres, as illustrated by the top image, divided the brain up into sections, and created a simplified network map, shown in the bottom image, which allowed them to mathematically test how connected the different areas were.
They used network theory, more typically used in social network analysis, which allows mathematical measures of network properties.
The researchers calculated which areas were the most connected to the rest of the network in terms of connections going directly in and out of the area, but also which areas were the most strategically important 'hubs'.
This meant the researchers could identify areas of the cortex that are the most highly connected and highly important, forming a structural core of the human brain.
You can see two of the maps on the right. The one in red illustrates which brain areas are the most highly connected. You can see it's the area at the top and back of the brain. As you can see better on the original image, its very centrally located, like a neural mohawk.
The image in blue on the right shows the network 'backbone', the information highways of the brain.
What's perhaps most interesting it that the most connected brain areas are many of those which are more active when we're at rest, compared to when we're engaged in a mental task that requires concentration and effort.
This has been dubbed the 'default network' in the scientific literature, and, rather annoyingly, the 'daydreaming network' by the popular press.
It's not entirely clear what the network is for, with some studies directly linked it to 'stimulus independent thought' (yes, daydreaming), while others more explicitly define it as internally focused, rather than externally focused thought and cognition.
Unfortunately, most cognitive neuroscience experiments work by measuring the effect of tasks on brain function, so a brain network which seems to be switched off by any sort of task is quite hard to study. A recent study found that even the noise of the brain scanner affects it.
Link to PLoS Biology article on brain connectivity. Link to write-up from The New York Times. Link to write-up from Neurophilosophy. Link to write-up from Science News.
Out of body experiences and grasping the ungraspable:
This week's ABC Radio National's All in the Minddiscusses what happens in the brain during out of body experiences, and why actions can be accurate even when our perceptions are not.
The first interview is with neurologist Olaf Blanke who discusses some of his recent compelling research, including a virtual reality experiment to induce out-of-body touch sensations in healthy participants and one with implanted brain electrodes to trigger full-blown out-of-body experiences in patients undergoing neurosurgery.
The second interview is with psychologist Melvyn Goodale, famous for his work on distinguishing the visual streams in the brain: the dorsal stream and the ventral stream.
Some of the most striking and important results from this work come from patients who have suffered damage to one or the other stream.
In the programme, Goodale talks about brain-injured patient DF, who can correctly and accurately grasp objects she cannot consciously 'see'. The opposite has been found in other patients, who can accurately see and describe objects they cannot accurately grasp.
This suggests that these two visual pathways, although complimentary, are specialised for different things, one for identifying objects, and the other for working out where they are and how to manipulate them.
The different function of the two pathways can also be demonstrated in healthy people as well.
You may recognise the visual illusion on the left, sometimes called the Titchener or Ebbinghaus illusion. The two circles in the middle are actually the same size, but look different due to their context.
Researchers have created a graspable version of the illusion by putting hoops on a flat surface.
When they've measured how people adjust their fingers to pick up the middle circles, they find that we don't over or underestimate the size. Our fingers are always perfectly adjusted to the actual size.
In other words, it seems that while our perception is fooled by the illusion, our actions aren't, showing how the specialisation of each visual stream can be seen in everyone.
There's now a minor cottage industry of research attempting to understand exactly what influences the effect.
UPDATE: "All in the Mind has been honoured with the Grand Award at 2008 New York Radio festivals for best entry across all categories, as well as a Gold World Medal in the Health / Medical category". - I'm sure it won't come as a surprise to most Mind Hacks readers but fantastic to have it recognised by the non-initiated!
Link to AITM on out-of-body experiences and other tricks of consciousness.
A scene from a thousand horror movies, retold in the medical literature, with an additional lesson about the correct use of cerebral perfusion and angiography in diagnosing the brain dead patient.
Presumably, learnt shortly after the doctors had stopped screaming.
I love the use of the phrase "the situation became confusing", just after the dead guy starts moving again.
Unusual movements, "spontaneous" breathing, and unclear cerebral vessels sonography in a brain-dead patient: a case report.
Bohatyrewicz R, Walecka A, Bohatyrewicz A, Zukowski M, Kepiński S, Marzec-Lewenstein E, Sawicki M, Kordowski J.
Transplant Proc. 2007 Nov;39(9):2707-8.
A patient with a brain injury fulfilled all clinical criteria for brainstem death diagnosis. Two standard sets of tests were performed; according to Polish regulations, the patient could be declared brain dead. However, shortly after the completion of the tests and before the final brain death declaration, 6 triggered "assisted" breaths/min were noticed. After careful analysis of the ventilator settings, it was concluded that low trigger sensitivity and airway pressure oscillations during heart contractions were the reasons.
Additionally, a few minutes later, spontaneous jerking movements of lower limbs and clonic movements of neck muscles secondary to painful stimuli were noticed. The situation became confusing; therefore, cerebral Doppler sonography was performed, showing circulatory arrest in both of the internal carotid, middle cerebral, and left vertebral arteries. The basilar artery was not visualized. Forward flow with increased pulsatility was recorded in extracranial and intracranial segments of the right vertebral artery. Cerebral circulatory arrest was still uncertain; therefore, the diagnostic procedures were completed with conventional cerebral angiography, which showed a lack of cerebral blood flow.
Finally, the patient was declared brain dead; kidneys and bones were harvested. Cardiogenic oscillations associated with incorrect low ventilator trigger settings may falsely suggest persistence of breathing efforts in a brain-dead patient. In the case of any unusual events during brain death diagnosis, cerebral perfusion tests should be performed with cerebral angiography as the "gold standard."
Over the last few months, the soul searching over the shortcomings of fMRI brain scanning has escaped the backrooms of imaging labs and has hit the mainstream.
Numerous articles in hard hitting publications have questioned some common assumptions behind the technology, suggesting a backlash against the bright lights of brain scanning is in full swing.
There are two strands to this debate, and both stem from the fact that the technology and conceptual issues of brain imaging are incredibly complex.
To fully understand what happens during a brain imaging experiment you need to be able to grasp quantum physics at one end, to philosophy of mind at the other, while travelling through a sea of statistics, neurophysiology and psychology. Needless to say, very few, if any scientists can do this on their own.
So the first strand involves how brain imaging experiments are reported in the media. Under the sheer weight of conceptual strain, journalists panic, and do this: "Brain's adventure centre located".
It's a story published this morning on the BBC News website based on an interesting fMRI study looking at brain activity associated with participants choosing a novel option in a simple gambling task. But out of the four words of the headline, only the first is accurate.
And this leads to the second strand of the debate, which, until recently, has been largely conducted away from the media's gaze, amongst the people doing cognitive science themselves.
It starts with this simple question: what is fMRI measuring?
When we talk about imaging experiments, we usually say it measures 'brain activity', but you may be surprised to know that no-one's really sure what this actually means.
Neuroscientist Nikos Logothetispublished an important paper in Nature a couple of weeks ago explaining exactly what we know so far about the link between what brain scans measure and what the brain is actually doing.
It's very wide-ranging and includes lots of grit-your-teeth hardcore neurophysiology, but is, I think, essential reading if you're neuroscientifically inclined.
It focuses on BOLD, the signal that reflects the ratio of oxygenated and deoxygenated blood measured by fMRI, and the fact that it can be altered by a huge range of different biological process and neural firing patterns.
One of the main points of the paper is that the brain is not simply an array of tiny localised processors, but it is more like an an ecosystem of communication.
Activity can result from sending more signals, trying to send less, or, from what seems to be particularly important - maintaining a balance of excitation and inhibition.
Furthermore, it seems that a great deal of neural activity is not from neurons that might be directly involved in a task, but from 'neuromodulation' - general processes of management and coordination, often linked to attention. This can wax and wane, can spread like ripples and can occur in all sorts of non-linear ways that makes interpretation difficult.
What this means is that brain imaging experiments need to be carefully designed to control for these effects, but this entirely depends on our understanding of the effects themselves.
In other words, our understanding of what brain scanning data tells us evolves over time. A study conducted ten years ago might mean something different now.
An article in Science, published in the same week as Logothetis' paper, reports on new statistical methods for interpreting imaging data, a different issue again.
The latest edition of The New Atlantis has an article that attempts to come to grips with some of the philosophical aspects of brain imaging experiments, in terms of the conceptual limits in inferring mental states from biological changes.
I have to say, it's a bit miscued in places, assuming that brain imaging relies on ideas about brain modularity (which it doesn't) and seemingly confusing it with the notion of pure insertion, and suggesting some rather strange notions about mental causation, but it has many good points and is worth a read.
It's important that these sorts of issues come to light, because it hopefully heralds a time of increased caution in our interpretation of brain scans - and that goes for scientists, the media and the general public.
This is essential, because this data is starting to be used, literally, in life or death decisions.
The same issue of The New Atlantis has an article on neuroimaging that discusses the ethical dilemmas in applying this imperfect technology to legal decisions concerning capital punishment.
Link to Logothetis on 'What we can do and what we cannot do with fMRI'. Link to Science article 'Growing pains for fMRI'. Link to New Atlantis on 'The Limits of Neuro-Talk'. Link to New Atlantis on Neuroimaging and Capital Punishment.
Michael Gazzaniga, one of the founding fathers of cognitive neuroscience and a pioneer of 'split brain' research, is interviewed on this week's ABC All in the Mind where he talks about the use and abuse of 'left brain - right brain' metaphors and how our understanding of free will is impacting on the law.
Gazzaniga was a student of Roger Sperry, who won a Nobel prize for his work on 'split-brain patients', people who had the two cortical hemispheres of the brain functional separated by neurosurgery to cut the corpus callosum in an attempt to treat otherwise untreatable epilepsy.
One of the amazing things was that while the people didn't feel any different, it was easy to demonstrate that the each hemisphere processed things in quite different ways and each was, to a certain extent, independently conscious.
The interview discusses some of this early research, and asks how much of the popular 'left brain - right brain' rhetoric that gets thrown around actually stands up to scientific scrutiny. I think you can guess, but it's good hearing it from the man himself.
Gazzaniga also talks about one of his other interests - neuroethics, and particularly the effect that a neuroscientific understanding of free will is having on our concepts of legal responsibility.
I was interested to read that US judges can now take courses in neuroscience to help them makes sense of the sometimes counter-intuitive findings in cognitive science.
As it happens, Gazzaniga's new bookHuman: The Science Behind What Makes Us Unique is published today. If you want a taster an Edgearticle by Gazzaniga from a few months ago seems to be taken from it.
The AITM Blog also has some bonus audio of Gazzaniga discussing his experience of being on George Bush's bioethics council when the President was vetoing stem cell cloning.
The New York Timescovers new research which has found significant cross-species variation in the structure of the synapse - the chemical 'connection points' that allow neurons to communicate.
The study itself has been published in Nature Neuroscience and the full text is available online for those who want the in-depth science.
A whole new dimension of evolutionary complexity has now emerged from a cross-species study led by Dr. Seth Grant at the Sanger Institute in England.
Dr. Grant looked at the interconnections between neurons, known as synapses, which until now have been regarded as a standard feature of neurons.
But in fact the synapses get considerably more complex going up the evolutionary scale, Dr. Grant and colleagues reported online Sunday in Nature Neuroscience. In worms and flies, the synapses mediate simple forms of learning, but in higher animals they are built from a much richer array of protein components and conduct complex learning and pattern recognition, Dr. Grant said.
The finding may open a new window into how the brain operates. “One of the biggest questions in neuroscience is to answer what are the design principles by which the human brain is constructed, and this is one of those principles,” Dr. Grant said.
The paper itself doesn't mention the issue, but I wander what implications this might have for the generalisation of animal experiments to humans.
The majority of cellular-level neuroscience research is done on animal tissue. While some of this focuses on the molecular level, where differences in the structure of, let's say, ion channels, would be easily apparent in comparison to humans, some studies simply look at the 'synapse' as the smallest functional unit.
In fact, a considerable amount of neuroscience research is done on the 1mm long microscopic worm C. elegans and the fruit fly, drosophila. This new research suggests that neuroscientists may need to be additionally cautious when assuming that the findings relate to general laws that might apply in humans.
UPDATE:Neurophilosophy has a great write-up of this study, which discusses it in more detail.
Link to NYT article 'Brainpower May Lie in Complexity of Synapses'. Link to PubMed entry for scientific paper. Link to full text.
New York Magazine has a wonderful article on the culture, controversies and pharmacology of caffeine - the world's most popular psychoactive drug.
Ranging from the recent upturn in coffee's popularity and its inevitable effect on our caffeine consumption to the science of its neurological effects, the article manages to capture some of the key debates about the tremor inducing buzz substance.
One particularly interesting part touches on research that suggests that, like the effect of nicotine, the lift for regular users may be nothing more than withdrawal symptoms being soothed to bring us back to baseline.
That all said, what if the uptick in energy, alertness, and smarts we feel after drinking a cup of coffee isn’t a real uptick at all? What if it’s an illusion? A group of cutting-edge caffeine researchers believes that might be the case...
When Griffiths and Juliano teamed up to review 170 years of caffeine research, much of which confirmed the drug’s reputation as a brain booster, they noticed a pattern: Most studies had been done on caffeine users who, in the interest of scientific rigor, were deprived of the stimulant overnight. Because caffeine withdrawal can commence in just twelve hours, by the time each study’s jonesing test subjects were given either caffeine or a placebo, they had begun to suffer headaches and fatigue.
For the half that received the stimulant—poof!—their withdrawal symptoms vanished. The other half remained uncaffeinated, crabby, and logy, and guess which group scored higher on cognitive tests time after time? The boost the test subjects who got the caffeine felt may have simply been a function of having been deprived of the drug.
Link to 'The Coffee Junkie’s Guide to Caffeine Addiction'.
Fantastic introduction to MRI brain scanning physics:
Magnetic resonance imaging is the most popular method for scanning the brain both for research and for clinical investigations. I've just found a wonderfully written article that gives a great introduction to the physics of how MRI scanners work.
It is both clearly written for the non-specialist and fantastically complete. This is a rare and valuable combination.
There are some other guides to MRI physics which are also wonderfully written but most lack the sufficient detail that would bring you up to 'entry level' in the field.
For example, How Stuff Work'sguide to MRI is a great place to start, but it won't tell you about why and how T1 and T2 imaging are different, or any of the other things you need to know to understand the fundamentals of MRI technology.
You don't need to know maths to understand the article (the downfall of most 'introductory' guides to MRI) and the author uses wonderfully clear analogies throughout.
The article is written by radiologist Robert Pooley, who should give himself a pat on the back for such a great job. It was published as an open-access paper in the journal RadioGraphics. Perfection!
Link to article 'Fundamental Physics of MR Imaging'.
In light of research showing that an ingredient in cannabis, cannabidiol, seems to actually reduce the risk of psychosis, I speculated previously on Mind Hacks whether smokers might be attracted to high-cannabidiol dope.
A study of UK street cannabis published in the Journal of Forensic Sciences suggests that cannabis resin (hashish) has the average highest rates of cannabidiol, while 'skunk' and imported herbal cannabis (weed) have the lowest.
For people who take cannabis, it's not the cannabidiol that makes you 'high', it's mainly a substance called tetrahydrocannabinol or THC.
There's accumulating evidence that THC increases the risk of psychosis, while cannabidiol reduces it - so the ratio of the two substances in the street drug might give a 'risk profile' in terms of mental health.
'Might' is the operative word here, as the research is still preliminary and the studies are still largely correlational with regard to cannabidiol-to-THC ratio and psychosis-like symptoms.
However, if this does turn out to be case, the new survey of UK street cannabis suggests that, on average, cannabis resin has higher levels of cannabidiol, with the implication that this might be less risky in terms of developing schizophrenia or other psychotic disorders.
This finding is an average over all the samples, however, and the study also found that resin had quite a bit of variability with regards to cannabidiol-to-THC ratio.
However, imported herbal cannabis and skunk was generally very low in cannabidiol. Additionally, skunk also had about 6 times the THC content of normal weed, making it especially potent.
The study concludes:
This study suggests that cannabis in England in 2005 remains a very variable drug with unpredictable pharmacological and psychological activity. The potency (THC content) of the cannabis varies widely, as does the content of other cannabinoids, especially in herbal cannabis and cannabis resin. The average potency within the country appears to be increasing, but large variations remain within and between different areas of the country.
CBD affects the pharmacological qualities of THC and reduces it psychoactive potential. The relative proportions of THC and CBD in resin are wide ranging, supporting the view that the potential effects of resin cannot be judged by measuring the THC content alone. The resin samples were all similar in appearance and gave the user no indication of their cannabinoid content.
Of the three principle forms of cannabis, sinsemilla [skunk] commonly had the highest THC content and almost totally lacked CBD. Had CBD been present it would have reduced the psychoactive potential of this material. In addition to having increased in potency, sinsemilla also appears to have become the most widely used form of cannabis. The current trends in cannabis use suggest that those susceptible to the harmful psychological effects associated with THC are at ever greater risk. This is due to the combined rise in potency and popularity of sinsemilla and the absence of CBD in this product.
The lead scientist in the study is called Professor Potter. Do with that fact as you will.
Link to abstract of Journal of Forensic Sciences study.
Neurophilosophy has collected some of the most unusual cases of penetrating brain injury from the medical literature, with x-rays that illustrate how some of the most curious objects can end up on the wrong side of the bony brain protector.
You may recognise a couple that we've notedbefore on Mind Hacks, but this is a far more complete and frankly quite surprising collection.
The most amazing is the case of a "32-year-old Caucasian male with a history of repeated self-injury drilled a hole in his skull using a power tool and subsequently introduced intracerebrally a binding wire from a sketchpad".
A striking, and, in some places, stomach churning collection of case studies.
Link to Neurophilosophy on unusual penetrating brain injuries.
What makes a man a genius? Russian neuroscientists were pondering this exactly this question in the early 1900s and did exactly what seemed sensible at the time - they collected and dissected the brains of some of the greatest cultural figures in a huge collection called 'The Pantheon of Brains'.
It's a fascinating story told in a recent article published in the medical journal Brain. Amazingly, the last brain was only added in 1989.
Rather fittingly, the collection contains the brains of some of the Russia's greatest psychologists and neuroscientists and has many curious aspects to it, such as the mysterious death of its founder. After death, his brain was immediately added to the collection.
In 1927, Bekhterev came up with a plan to organize ‘The Pantheon of Brains’ in Leningrad in order to collect elite brains. It was a severe irony of fate that precisely when the question about creating the Pantheon had been positively solved, the very initiator of this creation, Bekhterev, suddenly passed away. The circumstances are still questionable.
On December 17, 1927, the First All-Union Congress of Neuropathologists and Psychiatrists was held in Moscow. Bekhterev, along with L. S. Minor and G. I. Rossolimo, was elected as honourable chairmen of the congress. On December 23rd, the last day of the congress, Bekhterev gave a presentation during the afternoon session. In the evening, symptoms of a gastrointestinal disorder started and 24 hs later, Bekhterev died of (as officially stated) acute heart failure. Without any further post-mortem pathoanatomical investigation, his brain was removed, in accordance with his will, and his body was cremated the next day. However, the idea did not fade away.
In 1928, the neuroanatomical laboratory of Vogt and his Russian colleagues were reorganized into the Moscow Brain Research Institute, where the structured collecting and mapping of the brains of famous Russians started. Bekhterev did not see his plan come to fruition, but his own brain enriched the collection of the Moscow Institute (the weight of his brain was 1720g). The collection acquired the brains of Soviet politicians, famous writers, poets, musicians, etc.
It is not surprising that these included the brains of prominent Russian neuroscientists, such as neurologist, G.I. Rossolimo (1860–1928) - 1543g; physiologist, I.P. Pavlov (1849–1936) - 1517g; neurologist, M. B. Kroll (1879–1939) - 1520g; psychiatrist, P. B. Gannushkin (1875–1933) - 1495g; psychologist, L.S. Vygotsky (1896–1934). During the Soviet period, the work of the Moscow Brain Research Institute continued behind closed doors.
The collection was still expanding as recently as 1989, when it acquired the brain of A.D. Sakharov [A. D. Sakharov (1921–89) was an eminent Soviet nuclear physicist, dissident and human rights activist. He was an advocate of civil liberties and reforms in the Soviet Union. He was awarded the Nobel Peace Prize in 1975] — 1440g.
You gotta love the fact that the authors have added exactly how much each person's brain weighed.
Sadly, the full text isn't available online, although Brain does fully release articles after a set amount of time (a year I think) so it should eventually see the light.
I've just noticed this review article that concisely reviews what we know about how the street drug ecstasy (MDMA) affects the function of the brain.
In terms of life-threatening physical damage, MDMA is a great deal safer than most other recreational drugs including alcohol and tobacco, but there is increasing evidence that it impacts on memory, and the effect seems to be related to dose.
In other words, the more ecstasy you take, the more likely memory problems will be worse.
The neuropsychology of ecstasy (MDMA) use: a quantitative review.
Hum Psychopharmacol. 2007 Oct;22(7):427-35.
Zakzanis KK, Campbell Z, Jovanovski D.
A growing number of empirical studies have found varying neuropsychological impairments associated with use of 3,4-methylenedioxymethamphetamine (MDMA) use. We set out to determine to what extent neuropsychological abilities are impaired in MDMA users. To do so, meta-analytical methods were used to determine the magnitude of neuropsychological impairment in MDMA users across pre-specified cognitive domains. We found that cognitive impairment secondary to recreational drug use may result in what might be described as small-to-medium effects across all cognitive domains with learning and memory being most impaired. We also found that total lifetime ingestion of MDMA appears to be negatively associated with performance on tasks ranging from attention and concentration to learning and memory. Implications and limitations of these findings are discussed.
Sadly, the full-text of the paper isn't freely available online, but the main punchlines are in the summary.
Wired magazine has just published a must-read article on the hyping of neuroimaging technology by companies wanting to sell brain scans on the deceptive premise that they can tell you something about your mood and personality, the effectiveness of adverts or whether you're being truthful.
Here at Mind Hacks, we've covered several highlights in the ongoing parade of brain scan powered bullshit in the past (FKF Applied Research I'm looking at you) but this new article, by psychiatrist Daniel Carlat, is an engaging guide that tackles many of these issues in one go.
Neuroimaging studies that measure brain function are almost always done on large numbers of people and the results are usually only reliable when average differences between groups are compared. This makes it difficult to make sensible judgements about any one individual.
Brain scanning is also often reported as if it is revealing exactly which parts of the brain do what, but it typically only reports associations.
For example, an experiment might find that fear is associated with amygdala activation. But it's impossible to say the reverse, that every time the amygdala is activated, the person is fearful.
Here's an analogy. On average, people from New York may be more impatient than people from other cities.
If you predicted that all people from New York were impatient on the basis of this, you'd be grossly mistaken so many times that it would make your prediction invalid.
In fact, taking the average attributes of populations and applying them to individuals is stereotyping, and we avoid it because it is so often wrong as to cause us to misjudge people.
Alternatively, if you met an impatient person and therefore concluded that they must live in New York, you'd be equally inaccurate.
But this is essentially what these commercial brain scan companies are doing, but they are selling it as if it is reliably telling us about an individual person or an individual product because people tend to be blinded by the fact it just seems more scientific. After all, it's neuroscience right?
Scientists and responsible clinicians will know about these shortcomings and make sure they don't oversell their findings, but commercial companies are not selling you the data, they're selling you a way of make you feel better about your insecurities, whether they be commercial concerns or health worries.
Interestingly, the Amen Clinic comes in for criticism which seems to specialise in pushing and overinterpreting SPECT scans to patients.
These guys were the subject of a similarly critical article in Salon the other week and were pulled up the the Neurocritic blog last year for suggesting political candidates should be brain scanned to see what sort of people they are.
If you want to be immune to this sort of nonsense, the Wired article looks at some of the current commercial offerings and how they're trying to sell you short.
Link to article 'Brain Scans as Mind Readers? Don't Believe the Hype'.
Scientific American Mind tackles the neuroscience of orgasm in a feature article which has just been released online.
One of the merits of the article is that it avoids the 'men are simple, women are complex' stereotype and presents results from scientific studies that suggest there are both subtle similarities and differences in sexual response.
One problem with the area of sexual neuroscience is that it largely relies on brain scanning studies in humans.
You'll see from the article that there's lots of speculation as to what the changes in orgasm-related brain activity mean. It's largely blue sky thinking though, because it's always difficult to decide what is happening in the mind from the activity of particular brain areas. Take these paragraphs for example:
But when a woman reached orgasm, something unexpected happened: much of her brain went silent. Some of the most muted neurons sat in the left lateral orbitofrontal cortex, which may govern self-control over basic desires such as sex. Decreased activity there, the researchers suggest, might correspond to a release of tension and inhibition. The scientists also saw a dip in excitation in the dorsomedial prefrontal cortex, which has an apparent role in moral reasoning and social judgment—a change that may be tied to a suspension of judgment and reflection.
Brain activity fell in the amygdala, too, suggesting a depression of vigilance similar to that seen in men, who generally showed far less deactivation in their brain during orgasm than their female counterparts did. “Fear and anxiety need to be avoided at all costs if a woman wishes to have an orgasm; we knew that, but now we can see it happening in the depths of the brain,” Holstege says. He went so far as to declare at the 2005 meeting of the European Society for Human Reproduction and Development: “At the moment of orgasm, women do not have any emotional feelings.”
It's like trying to guess what's happening in a city just by looking at changes in traffic flow. The upsurge in traffic on the high street could mean it's a busy shopping day, but it could also mean there's a carnival, or a riot, or funeral, or any other strange or unusual occurrence you might never have predicted.
Brain scanning just finds associations, but to find out whether an area is causally involved in a particular function, or whether it is necessary for the function, research with brain injured patients is one of the most powerful methods.
For example, if you think a brain area is necessary for orgasm, or a certain component of orgasm, a person with damage to that area should not experience what you've predicted.
We know that sexual problems are common after brain injury, but virtually no research has been done to see how damage to specific brain areas affects orgasm.
This would be important, both to help us understand the neuroscience of orgasm beyond general speculation, but also to begin to understand how we can help brain injured people regain satisfying sex lives.
Undercover genetics and the function of the brain:
Science News has an article on one of the most important future topics in neuroscience - epigenetics, the science of how information coded in the genes is used when the brain does its work.
Almost every cell in the body has a copy of the DNA, and therefore has the capability to express any protein.
But you wouldn't want proteins that are used for digesting food produced in the brain, so the body has various ways of regulating which proteins get expressed at any one time. This is epigenetics.
If DNA is like a blueprint, epigenetics is the committee of civil engineers that coordinate the construction site.
We've known from twin studies and molecular genetic research that genes and the environment both influence cognition and behaviour, but these studies only give statistical associations. What they don't tell us is how this happens.
In a sense, epigenetics is the scientific glue that allows us to understand how genes influence learning and behaviour, but also how learning and behaviour influences the expression of genes.
In other words, its goal is to explain how the environment combines with genetic information in the brain.
Needless to say, much epigenetic research is focusing on mental illness, the classic example of how genetic risk, experience and environment combine with sometimes disastrous consequences.
One of the most interesting aspects is that there is growing evidence that epigenetic information can be inherited. So your experiences may actually cause changes to gene regulation that are then passed on to offspring.
Link to Science New article on epigenetics. Link to abstract of good review article on epigenetics and cognition.
Neurophilosophy has a fascinating article on the recent archaeological discovery of numerous ancient Incan skulls of which over 1 in 6 showed signs of trepanation - an ancient form of brain surgery where a hole was drilled in the skull.
What's surprising is just how common it was. 66 skulls from Incan burial sites had a total of 109 trepanation holes. Some, like the one pictured, obviously needed a significant amount of skill and practice to complete.
And with this many examples, the archaeologists could make some fascinating inferences about the purpose and success of these operations:
Andrushko and Verano argue that the Incas performed trepanation primarily to treat head injuries incurred during battle, because the holes are most often found at the front of the skull to the left, consistent with injuries caused by a right-handed opponent during face-to-face combat, and because adult males are overrepresented in the sample. The procedure was evidently used to treat mastoiditis (an infection of the region of the temporal bone behind the ear) as well.
The authors also show that the success rate of the procedure improved with time, as the Inca empire progressed and made advances in medicine. The earliest specimens, dated to around 1,000 A.D., showed no signs of bone growth around the perforations, suggesting that the procedure was often fatal. But specimens dating to around 400 years later suggest a survival rate of around 90%.
Link to Neurophilosophy article on prehistoric Inca neurosurgery.
Phantom limbs are a well-known phenomenon where sensations and feelings are still experienced from a missing limb. In rare cases after brain injury, an additional phantom limb can appear - causing the sensation of a phantom third hand, arm or leg.
The drawings on the left are from two case studies of people with these 'supernumerary phantom limbs' recently published in the journal Neurology. They show an artist's impression of the body sensations of two patients who suffered brain stem strokes.
Both patients had the experience of having a third arm and a third leg, although the male patients had the leg 'appear' along the midline of the body, while the female patient seemed to experience it 'superimposed' upon an existing leg.
One distressing element for the female patient was that although the patient could 'move' the phantom arm voluntarily, "she described occasional loss of control and feeling strangulated by the phantom arm around the neck".
Two earlier case studies from neuropsychologist Peter Halligan and colleagues reported similarly disembodied extra limbs, but this time after damage to the right hemisphere of the brain.
As is more common after right hemisphere damage, these tended to have a delusional quality, so they weren't just sensations - the patients genuinely believe their additional limbs existed.
One gentleman believed that he had a third arm in the middle of his body, and another believed that he had a third hand.
In this last case, the patient reported actually 'seeing' the additional limb, similar to this case study of a gentleman who believed he had a third leg protruding from his left knee after suffering a stroke that affected the thalamus:
He consistently maintained that the phantom leg was attached to his knee with a "bone plate" that "had no flesh on it". However, he reported that the phantom limb itself looked normal and had a shinbone and a foot. It usually "appeared" in the morning when he was helped to put on his trousers. The patient stated that the phantom limb prevented him from turning over in bed, but did not adversely affect him otherwise.
When asked about how he knew about this leg he said that he could see it (despite his severe visual impairment) and feel it with his hand. He believed that the phantom limb belonged to him, although he readily accepted that it was not "normal" to have three legs. Initially he reported that the "leg" was growing from his own knee, but then reasoned that (given its size) he would have noticed it before the stroke.
At other times he believed the leg was attached to him by the nursing staff, but could not explain why. The patient was aware of phantom limb phenomena as his wife was an amputee. He was also aware that a stroke may affect perception and cognition. He did not believe either issue applied in his case.
The experience of a 'supernumerary phantom limb' is usually the result of a brain injury and typically resolves over time.
Phantom limbs are thought to arise because the somatosensory cortex, the part of the brain that represents the body's sensations and feelings, reorganises so that the area previously used to represent the limb is partially 're-used' for other functions, meaning the sensations sometimes get activated when these other functions are active.
Nevertheless, supernumerary phantom limbs are still mysterious, largely due to the small number of cases and diverse brain areas involved.
There is some suspicion that they might be caused because of disrupted communication between parietal lobes, which are known to represent body image, and the sensory feedback from the nerves in the body.
Link to abstract of Neurology case studies. Link to full text of 1993 case study. Link to full text of 1995 study.
I'm thoroughly digging the brain section of the Radiology Picture of the Day website. As you might expect, it's a wonderfully geeky place where radiologists post an image every day, often brain CTs or MRIs, with a little gem of wisdom with each one.
One of the most interesting is the pictured CT scan with a 'ring artefact'. I've contrast enhanced the image so you can see the circle or ring near the centre a little more clearly.
It's a known imaging problem caused by poor calibration of the scanner.
However, the Radiology Picture of the Day entry notes that these were given special significance by the quacktastic German physician Ryke Geerd Hamer who claimed that his 'New Medicine' could cure 98% of all cancers.
He gave these rings the rather immodest name 'Hamer Foci' and if they appeared in the brain, apparently this meant cancer was elsewhere in the body.
For Hamer, cancer was simply the body's reaction to a psychological conflict, and presumably this was what he thought the CT scanner was picking up.
This is despite the fact that CT scans only picture large scale structure on which psychological changes make no recognisable impact.
To coincide with stroke awareness month, a new report from the US Government's Center for Disease and Control and Prevention has highlighted that less than half of people surveyed could identify the potentially life-saving early warning signs of stroke.
A stroke, known medically as a cerebrovascular accident, is where the blood supply to the brain is interrupted because of blockage or damage to an essential blood vessel.
It can be fatal, and more often leads to significant brain damage, but this can be limited or a life potentially saved if it is detected and treated as soon as possible.
The following are warning signs of stroke. If someone you know experiences any of these, call an ambulance or get them medical care as soon as possible.
Sudden numbness or weakness of the face, arm or leg, especially on one side of the body
Sudden confusion, trouble speaking or understanding
Sudden trouble seeing in one or both eyes
Sudden trouble walking, dizziness, loss of balance or coordination
Sudden, severe headache with no known cause
To reduce your chances of having a stroke, you need to look after your cardiovascular health.
Essentially, healthy body, healthy brain - so alcohol, smoking, excess fatty food, little exercise and head injury will increase the chances of blood supply problems in the brain.
Link to CDC report on stroke awareness. Link to write-up from Yahoo! News.
The Telegraph has an article and video on the Harvard 'baby brain lab' and some of its recent discoveries which are helping us understand how the mind and brain develops through the earliest months of life.
The research team is otherwise known as the Laboratory for Developmental Studies and is headed up by developmental psychologist Elizabeth Spelke who's interviewed on the video.
You would think babies are difficult to test with behavioural experiments because they are can't even stick to simple procedures, so developmental psychologists have created a task that takes advantage of the fact that infants stare at things when they're new or interesting, but get bored and stop looking at the things they've seen before.
Let's say you wanted to test whether newborn babies can tell the difference between familiar and unfamiliar people when they see their faces from different angles.
You show a picture of a person's face, facing directly forward, until the infant becomes bored and starts looking away.
Then you flash up two new pictures both taken at the same angle, one of the original person and one of a new person. You then measure how long the infant looks at each face.
Because infants look at new or different things for longer, they would spend more time looking at the unfamiliar face if they can genuinely tell the difference. If they both seem the same to the infant, they should look at both equally, on average.
In fact, this was a recent study done on 1 and 2-day old babies, and it turns out they can tell the difference between a familiar face and a new face when the change in viewing angle isn't too great.
Variations on this simple procedure have taught us a great deal about what babies can perceive, understand or expect, as well as how their brains function when they're doing these tasks.
What is often most surprising is what babies can do within their first few days or birth - such as recognise faces, as in the study above - but the debate about how much these sorts of skills are due to innate knowledge, or innate rapid learning mechanisms, are still raging:
Newborns have no idea what they look like, yet they enter the world equipped with a basic understand of what a face is. They know that the pink blob in the middle of a face is a tongue, and that they can poke out their own tiny tongue in just the same way. This was crucial ammunition for an intellectual war that still rages over whether we emerge from the womb as general-purpose learning machines that soak up details of our environments, or, as Spelke believes, born 'precocious', so we can immediately do things that are key to survival (just as newly-hatched chicks and fish can immediately do things such as navigate, or find and recognise food).
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Spelke has crossed swords with Professor Mark Johnson of Birkbeck's Centre for Brain and Cognitive Development in London, whose studies of infant brains stretch back nearly two decades. He points out that the four and six month olds at Spelkeland have hundreds of hours of experience in categorising the world, which challenges Spelke's 'core knowledge' theory. He believes that we enter the world with 'soft biases to attend to different aspects of the environment, and to learn about the world in particular ways'.
His colleague, Prof Annette Karmiloff-Smith, who once worked with Piaget, praises some of the Spelkeland work ('Liz has done some great behavioural experiments') but adds, 'Paradoxically, although she studies babies, in my view she doesn't raise questions about infants' capacity for learning, which may account for their extraordinary abilities without the need for them to be born with pre-specified knowledge.'
Link to article 'Harvard's baby brain research lab' (via 3QD). Link to video of Spelke interview.
This is an excerpt from quite possibly the geekiest forensic pathology article I have ever read. Three pathologists discuss the physics of how a Mexican coin ended up in the brain of a dead shooting victim.
They speculate he may have been holding it in his hand while shielding his head and the bullet impacted on the coin and both ended up deep in the brain. Oh, but with maths.
The images on the left are an artist's reconstruction of the position of the man when shot and the path of the bullet, and a photo of the coin in the dead man's brain.
Items that become accessory or secondary projectiles usually possess a minimal amount of energy, producing superficial or insignificant wounds. The secondary projectile in this case, a coin, gained sufficient kinetic energy to penetrate the scalp, skull, and brain. We believe the coin was being held by the decedent in his left hand next to his head at the time of the shooting. The bullet passed through the hand, producing the described injury and picking up the coin as a secondary projectile before entering the head.
The coin, a 1970 Mexican 50-centavo piece, was 25 mm in diameter with a weight of 6.4 g. In comparison, the diameter of a 1970 U.S. quarter dollar coin is 24.3 mm with a weight of 5.6 g. Both coins contain a mixture of copper and nickel, and the U.S. coin is coated with silver. The mixture of nickel and copper is relatively soft and permits deformation, as seen in this case. The primary projectile, a .380-caliber automatic Colt pistol 9- × 17-mm Winchester Silvertip bullet, weighs 5.1 g, with a rated muzzle velocity of 304 m/second (1000 feet/second). The mass of the conjoined projectile more than doubled with addition of the coin, yet retained sufficient velocity to produce the described lethal injury.
We attempted to see if this would be theoretically possible using some simple physical principles. Under ideal conditions, this event represents a form of an inelastic collision. We assumed that there was conservation of momentum between the oncoming bullet and the departing conjoined bullet-coin mass that subsequently penetrated the skull and brain. If momentum is conserved during this collision, then the mass of the bullet multiplied by its velocity would equal the mass of the conjoined bullet and 50-centavo coin multiplied by their departing velocity. The velocity of the bullet just prior to striking the coin is unknown and could not be determined.
For our calculations, we used the known muzzle velocity of this ammunition, understanding the limitations of such an assumption. We also calculated the kinetic energy and momentum of the oncoming bullet and exiting conjoined bullet-coin before and after collision. The results indicate two things: as expected in an inelastic collision, the kinetic energy of the conjoined bullet and coin is much less than that of the oncoming bullet, and the velocity of the conjoined projectile drops by greater than a factor of two. No doubt some of this loss in kinetic energy resulted from the energy expended in deforming the Mexican coin. The calculated loss in velocity of the bullet postcollision slows this projectile (i.e., the conjoined bullet/coin) to <150 meters per second (<450 feet/second). However, this velocity would still be well in excess of the minimal velocity needed to penetrate skin and bone, which has been reported to be about 66 meters per second (200 feet/second).
Forensic pathology has this morbid deadpan geekiness about it which just makes it so interesting to read.
You can just see them in the pathology room, arguing about what happened and sketching calculations on the back of envelopes.
In the wake of the Naturesurvey that found that 20% of scientists admit to using brain enhancing drugs, Wired has just published an article detailing what drugs their scientist readers use to keep on keepin' on.
Although the drugs issue is obviously the headline-grabber, the publication also has a great feature on cognitive enhancement that largely covers tips, tricks and techniques to boost your mental skills that aren't drug-related.
The article itself is anecdotally interesting, but has a curious tone throughout:
Surprisingly large numbers of people appear to be using brain-enhancing drugs to work harder, longer and better. They're popping pills normally prescribed for narcolepsy or attention-deficit disorder to improve their performance at work and school.
"We aren't the teen clubbers popping uppers to get through a hard day running a cash register after binge drinking," wrote a Ph.D. research scientist who regularly takes a wakefulness drug called Provigil, normally prescribed for narcolepsy. "We are responsible humans."
Whenever people talk about using drugs, they're always keen to distance themselves from that sort of drug user. You know, the ones that aren't responsible.
This belies the fact that most people use most drugs with few problems. Even teen clubbers popping uppers.
While all drugs have risks and illicit street drugs increase the health risks and definitely have an impact on body and brain function, it's only a minority of drug users who have problems that interfere with their daily lives.
For example, a recent study found that 4% of Australian workers use the (fairly nasty) drug methamphetamine. The figure rises to over 11% for 18-29 year olds. That more than 1 in 10.
While the study found that using methamphetamine significantly increases chances of a range of health problems, it's still the minority of users that report significant problems. This is the typical pattern for studies on drug use.
In other words, drugs are bad for you but most people manage the risks. A small minority, of course, don't, and die instantly or suffer long-term consequences.
The benefit and using and abusing prescription drugs for 'brain doping' is largely in the fact that you can be sure of the purity of the product and that probably (depending on how you acquire them) you're not funding a vicious criminal network.
At the end of the day though, the process is the same, whether you're using legal drugs, illegal drugs, for recreation or for performance.
Just make sure you're educated about the risks and know the consequences. Just like everything else in life.
Link to Wired.com Readers' Brain-Enhancing Drug Regimens. Link to Wired 'Give Your Intellect a Boost' techniques.
This month's Trends in Cognitive Sciences has a fantastic review article on the neuroscience of meditation - focusing on how the contemplative practice alters and sharpens the brain's attention systems.
The full article is available online as a pdf, and discusses what cognitive science studies have told us about the short and long-term impact of meditation on the mind and brain.
Meditation is now being quite extensively studied by cognitive science owing to the clear effects it has on the brain, and on the increasing evidence for its benefit in mental health.
A recent review of 'mindfulness' meditation-based therapy found that although research is in its early stages and not all possibilities have been ruled out, there's good evidence from the existing RCTs that it's particularly good in preventing relapse in severe depression.
The Trends article, which largely focused on the neuroscience research, makes the distinction between two types of meditation: 'focused attention' meditation - that involves focusing on a particular thing and refocusing if you become distracted by thoughts or sensations; and 'open monitoring' meditation which involves nonreactively monitoring the content of experience and acting as almost a detached observer to feelings and mental events.
This is an excerpt where the authors discuss the experimental evidence for the long-term 'open monitoring' or OM meditation:
Long-term practice of OM meditation is also thought to result in enduring changes in mental and brain function. Specifically, because OM meditation fosters nonreactive awareness of the stream of experience without deliberate selection of a primary object, intensive practice can be expected to reduce the elaborative thinking that would be stimulated by evaluating or interpreting a selected object. In line with this idea, Slagter et al. recently found that three months of intensive OM meditation reduced elaborative processing of the first of two target stimuli (T1 and T2) presented in a rapid stream of distracters...
Because participants were not engaged in formal meditation during task performance, these results provide support for the idea that one effect of an intensive training in OM meditation might be reduction in the propensity to ‘get stuck’ on a target, as reflected in less elaborate stimulus processing and the development of efficient mechanisms to engage and then disengage from target stimuli in response to task demands. From the description in Box 2,we anticipate a similar improvement in the capacity to disengage from aversive emotional stimuli following OM training, enabling greater emotional flexibility.
Moreover, the article includes many other studies that have reported interesting effects. For example, highly experienced focused attention meditators need minimal effort to sustain attentional focus, while even shortcourses on meditation can improve attention and decrease stress.
Most of the techniques are taken from Buddhist meditation practices and I'm sure Buddhists are cracking a wry smile as cognitive science is just starting to catch on to what they've been noting for thousands of years.
As for the neuroscience, I'm sure the remarkably science-savvy Dalai Lama is fascinated as he's held a number of conferences with leading researchers to discuss the the intersection between Buddhist practice and cognitive science.
It is now quite widely known that cannabis use is linked to a small but significant increase in the chance of developing psychosis, but it is less widely known that one of the ingredients in cannabis actually has antipsychotic effects.
Unlike THC, it's lesser known cousin cannabidiol is not responsible for the cannabis 'high' but it is naturally present in the plant.
There is accumulating evidence that cannabidiol has an antipsychotic effect, potentially damping down the psychosis-promoting effects of THC.
The amount of this substance varies in street cannabis, with some strains having more cannabidiol than others, and 'skunk' having the least of all - it being mostly eliminated by selective breeding for high THC content.
An ingenious new study looked at levels of cannabidiol consumption in groups of cannabis smokers by testing hair samples, and found that the groups who had the lowest cannabidiol levels had the most psychosis-like experiences.
In contrast, those with the most cannabidiol levels had the least psychosis-like experiences - equal to a comparison group with no detectable cannabis compounds who were presumably non-smokers.
One caveat is that the participants were all recruited from a study on ketamine users (a substance known to raise the risk of psychosis), so the study will have to be repeated on people who solely use cannabis to be sure the effect isn't a specific interaction between the two drugs.
However, the results seem to tie up with what we already know about how THC and cannabidiol work, so may reflect a genuine effect.
As any visitor to Amsterdam will tell you, cannabis breeders often try to maximise THC content to grow a plant with more 'bang for the gram'.
As cannabidiol seems to have no effect on the high itself, perhaps we might see breeders also trying to maximise the cannabidiol content in future, potentially reducing the risk to smokers' mental health.
UPDATE: A reader who prefers to remain anonymous sent in the following interesting comment:
Cannabidiol is in fact bred for in cannabis product, but is mainly done for taste. There are mentions within the cannabis breeding literature (i.e. seed catalogues) on breeds which lack psychosis (often defined as "low paranoid strains"), and these correspond to the "tasty" breeds to a great extent.
Probably 'lacking psychosis' would be considered controversial by the scientific community, but it's interesting that the growing and smoking community make the distinction between high and low 'paranoid strains'. It'd be interested to see whether these stand up to scientific investigation.
The New York Times has a fantastic article on the remarkable artistic talent seemingly released in some people with fronto-temporal dementia (FTD) - a condition where frontal and temporal lobes start deteriorating.
Dementia is any condition where the brain or brain function deteriorates quicker than would be expected through normal ageing.
This can occur because of still poorly understood Alzheimer's-like changes involving abnormal protein accumulation in the brain, or often, because the blood vessels start dying and deteriorating, leading to the death of the brain areas they serve.
A mix of both is not uncommon but the damage to the brain is often uneven and patchy, meaning that while mental function generally declines, specific skills and abilities can be impaired while others are left relatively intact.
Some brain areas are particularly involved in controlling or inhibiting others, meaning if these areas are damaged, the areas they 'control' can suddenly begin to work overtime (its like if you damaged the break on a car, often it would speed up when you didn't want it to).
In fact, if these systems break down due to brain damage, we can regain reflexes we had when we were first born - such as automatically grasping things put in the hand - but which the brain inhibits as it matures.
The NYT article discusses a recent case study published in the medical journal Brain that suggests that this same process may release brain circuits leading to new artistic talents and skills.
From 1997 until her death 10 years later, Dr. Adams underwent periodic brain scans that gave her physicians remarkable insights to the changes in her brain.
“In 2000, she suddenly had a little trouble finding words,” her husband said. “Although she was gifted in mathematics, she could no longer add single digit numbers. She was aware of what was happening to her. She would stamp her foot in frustration.”
By then, the circuits in Dr. Adams’s brain had reorganized. Her left frontal language areas showed atrophy. Meanwhile, areas in the back of her brain on the right side, devoted to visual and spatial processing, appeared to have thickened.
When artists suffer damage to the right posterior brain, they lose the ability to be creative, Dr. Miller said. Dr. Adams’s story is the opposite. Her case and others suggest that artists in general exhibit more right posterior brain dominance. In a healthy brain, these areas help integrate multisensory perception. Colors, sounds, touch and space are intertwined in novel ways. But these posterior regions are usually inhibited by the dominant frontal cortex, he said. When they are released, creativity emerges.
The art of Anne Adams, the subject of the case study, can be seen on twowebsites and the NYT article contains a couple of striking pieces.
Link to NYT article 'A Disease That Allowed Torrents of Creativity'. Link to PubMed abstract of scientific study.
Defining brain death and the controversies of existence:
The Boston Globe has an interesting article on the concept of 'brain death'. The criteria for brain death are being contested and it's become a hot issue, partly because the US allows organs from consenting donors to be removed when brain death has been diagnosed.
The 'dead donor rule' stipulates that it's only possible to remove organs in cases where a person has died, and this can either be after cardiac death, where the heart and lungs stop functioning, or after brain death, where the brain suffers irreversible damage which causes coma where the patient is kept alive solely by life support.
Most organs donated from the deceased come from people who have been diagnosed as brain dead. Organs remain viable for only about an hour or two after a person's last heartbeat. Brain dead patients are ideal candidates for organ donation, then, because they are kept on ventilators, which means their heart and lungs continue to work, ensuring that a steady flow of oxygen-rich blood keeps their organs healthy. Surgeons remove the donor's organs, then shut off the ventilator. The patient's heart eventually stops.
Yet a small but vocal minority in the medical community has always insisted that some brain dead patients may not be dead. For instance, one study documented some kind of brain activity in up to 20 percent of people declared brain dead, suggesting to some critics that doctors sometimes misdiagnose the condition. Although some neurologists contend the claim, University of Wisconsin medical ethicist Dr. Norman Fost points to research showing that many "brain dead" patients have a functioning hypothalamus, a structure at the base of the brain that governs certain bodily functions, such as blood pressure and appetite.
It's an challenging that speaks directly to our idea of what divides life and death. There is no question that any of the patients will recover, regardless of any residual activity detected in their brain.
But it prompts the question of what sort of brain activity we consider human enough to constitute life.
Of course, the issue is compounded by the importance of life-saving organ donation operations, for which suitable organs are almost always in short-supply.
Wired Science have got a great short film that follows a two people who have deep brain stimulation devices implanted in their brains to treat tremors.
Tremor is a symptom of Parkinson's disease and this was one of the earliest targets for early DBS trials.
The film follows someone who has exactly this difficulty, plus someone who has a different form a tremor disorder, known as essential tremor, through the process of the operation.
While most people assume brain surgery is all pre-planned beforehand, for many treatments for cognitive or behavioural functions, the surgeons need to wake up the patient after they've open their skull to make sure they're targeting the right place (and avoiding damaging essential functions).
In this case, they wake the patients up during neurosurgery so they can test out their movements while stimulating different areas of the brain, in a trial and error style.
Wired Science also has a shorter film online about the post-mortem dissection of a brain of a patient who had Alzheimer's disease that's also well worth having a look at.
Link to video of deep brain stimulation neurosurgery. Link to video on 'The Brain of an Alzheimer's Patient'.
A case of a man with unstoppable hiccups has just been published online in the medical literature. Rather unusually, it turned out they were caused by early stage Parkinson's disease.
Parkinson's disease is most commonly associated with movement difficulties and the public most associate it with tremor or shaking.
However, it can have a wide range of other effects (more recently, problems with cognitive functions and mental health have been recognised), although this seems to be the first time hiccups have been reported as an early symptom.
The case study is reported in the journal Parkinsonism and Related Disorders:
The patient was a 62-year-old male who had been suffering from intractable hiccups for more than 6 months. The initial intermittent nature of hiccups became continuous over time. When he was quiet, the hiccups were more prominent, although his symptoms tended to decrease when he was speaking.
The hiccups frequently interrupted his speech particularly towards the end of a sentence. The hiccups tended to disappear when he was asleep. Hiccup frequency increased with emotional stress such as anxiety and anger. The patient was depressed and socially isolated due to the embarrassment caused by his continuous hiccups.
It's a curious case, but the paper also contains a fascinating paragraph on the causes of hiccups. One cause can be with (unsurprisingly) the organs in the chest, but another can be disruption to part of the brainstem called the medulla.
The causes of hiccup can be divided into ‘peripheral’ and ‘central’. A wide variety of peripheral conditions can cause hiccup including: gastroesophageal pathologies, renal failure, malignancies, medications, abdominal surgery and even myocardial infarction.
Central causes can result from structural or functional disorders of the medulla or various other supraspinal neural elements such as multiple sclerosis, medulla oblongata cavernoma, brainstem tumors, basilar artery aneurysm, cerebellar hemangioblastoma, dorsal and lateral medullary infarctions...
The antidopaminergic agent chlorpromazine is the only drug approved for the treatment of intractable hiccups.
I never knew there was an approved drug for difficult to control hiccups, let alone chlorpromazine, the first antipsychotic drug to be developed and widely used in the 1950s.
However, stranger treatments have been discussed in the medical literature.
Perhaps some of the finest moments in hiccup medicine have come from the small but determined literature on the use of digital rectal massage (translation: finger up the arse) as a treatment.
The abstract of 1990 article from the Journal of Internal Medicine is fantastic simply for its deadpan delivery. Needless to say, it was honoured with an IgNobel award.
Could you endure such pain, at any hand but hers?:
I finally got round to having a look at the New York Timesmigraine blog and found it full of fantastic writing and some wonderful artwork that aims to capture the perceptual distortions associated with the mother of all headaches.
There's a particularly good article by Oliver Sacks (his first book was on migraine) who discusses the common geometrical patterns that can occur in the hallucinatory images, known as a form constants.
Interesting, the mathematician Paul Bressloff has suggested [pdf] that these necessarily arise when the firing of neurons in the primary visual cortex is destabilised.
Although Bressloff was particularly addressing certain hallucinations caused by psychedelic drugs, the form constants are, well, constant across conditions, so are likely to arise from a similar process in migraines too.
There are many more articles describing the science, personal stories and art of the head pounding, vision distorting and stomach churning headache. The gallery is particularly good if you're not familiar with the range of visual effects.
However, no one seems to have touched on a poem by Robert Graves where he uses migraine as a metaphor for love (or is it the other way round?) capturing the beauty and pain of both.
Symptoms of Love
Love is universal migraine,
A bright stain on the vision
Blotting out reason.
Symptoms of true love
Are leanness, jealousy,
Laggard dawns;
Are omens and nightmares -
Listening for a knock,
Waiting for a sign:
For a touch of her fingers
In a darkened room,
For a searching look.
Take courage, lover!
Could you endure such pain
At any hand but hers?
Frontal Cortex has alerted me to a wonderful article in The New Yorker about Stanislas Dehaene's work on understanding the neuropsychology of number sense.
Like written and spoken language, human numerical abilities are quite astonishing for how they are organised in the brain.
After brain injury, various maths or numerical abilities can be shown to 'doubly dissociate', meaning that parts of the ability can be independently damaged and so it can be inferred that they rely on independent (but, of course, interacting) brain systems.
The surprise comes from the fact that as a species, abilities like complex language, writing and maths are relatively recent cultural innovations.
While some of the core abilities may be inherited, there must be some aspects of the more complex skills which become tied up with the development of brain structure as we grow to account for the way in which they break down in very selective ways after brain damage.
Dehaene is one of the key researchers in understanding the neuropsychology of numerical ability and what he calls 'number sense' - a more general intuitive perception of quantity and number.
It has been suggested that this is also linked to other ways of perceiving the world, as can be seen from some strange interactions between number and space that can be seen in experiments:
But the brain is the product of evolution—a messy, random process—and though the number sense may be lodged in a particular bit of the cerebral cortex, its circuitry seems to be intermingled with the wiring for other mental functions. A few years ago, while analyzing an experiment on number comparisons, Dehaene noticed that subjects performed better with large numbers if they held the response key in their right hand but did better with small numbers if they held the response key in their left hand.
Strangely, if the subjects were made to cross their hands, the effect was reversed. The actual hand used to make the response was, it seemed, irrelevant; it was space itself that the subjects unconsciously associated with larger or smaller numbers. Dehaene hypothesizes that the neural circuitry for number and the circuitry for location overlap. He even suspects that this may be why travellers get disoriented entering Terminal 2 of Paris’s Charles de Gaulle Airport, where small-numbered gates are on the right and large-numbered gates are on the left. “It’s become a whole industry now to see how we associate number to space and space to number,” Dehaene said. “And we’re finding the association goes very, very deep in the brain.”
The article is a great read and a useful introduction to some of the key findings in the field, as well as containing a whole load of eye-opening findings about number and the brain.
A fantastic study has just been released by open-access science journal PLoS One that investigated the neuroscience of jazz improvisation.
Jazz musicians were put inside an fMRI brain scanner and were asked to do complete a number of different musical exercises using a specially adapted magnet-friendly keyboard.
The musicians were asked to demonstrate musical scales, a pre-practised fixed piece, and an improvisation exercise while their brains were scanned.
A summary of the study by the John Hopkins medical school team gives the main results:
The scientists found that a region of the brain known as the dorsolateral prefrontal cortex, a broad portion of the front of the brain that extends to the sides, showed a slowdown in activity during improvisation. This area has been linked to planned actions and self-censoring, such as carefully deciding what words you might say at a job interview. Shutting down this area could lead to lowered inhibitions, Limb suggests.
The researchers also saw increased activity in the medial prefrontal cortex, which sits in the center of the brain’s frontal lobe. This area has been linked with self-expression and activities that convey individuality, such as telling a story about yourself.
Some years ago, psychiatrist Sean Spence suggested that Jazz music may have been born owing to the 'the father of Jazz', Buddy Bolden, having schizophrenia and suffering from associated frontal lobe impairments.
Spence argued that reduced frontal lobe function meant that Bolden could only improvise, as he didn't have the cognitive control to stick to pre-learnt pieces.
At the time improvisation was considered a sign that you couldn't play 'proper music' well enough, but Bolden took improvisation to a new level with wondrous flights of fancy and, as the legend goes, jazz was born. That's not the whole story of course, but it's possibly an ingredient.
While these new findings don't give us much of a lead on whether this might have been the genuine beginning of jazz music, it's interesting that the idea that reduced frontal lobe function 'frees up' the over-inhibited playing of set pieces, is consistent.
Link to PLoS One article on the cognitive neuroscience of Jazz. Link to study summary. Link to BBC News on Spence's theory.
Dopamine has been the big player in understanding schizophrenia since antipsychotic drugs were discovered. All current antipsychotics have their main effect by blocking dopamine function in the mesolimbic pathway and there's now significant evidence that this is the location of one of the major dysfunctions.
It's been clear for a while that this isn't the whole story though. Ketamine and PCP, two glutamate-focused drugs that barely touch the dopamine system directly, are heavilylinked to schizophrenia and can intensify psychotic symptoms.
Findings such as these have sparked a flurry of interest in understanding the role of glutamate in psychosis, and there's now an intense interest in developing drugs that might target this system.
One of the key hopes is that these newer drugs will have fewer side-effects, as, in some, antipsychotics are have unpleasant and unhealthy adverse consequences.
The New York Times has just published a great article on the development of these new drugs, just in mid-testing stage, and on the neuroscience that motivates them.
People who use PCP often have the hallucinations, delusions, cognitive problems and emotional flatness that are characteristic of schizophrenia. Psychiatrists noted PCP’s side effects as early as the late 1950s. But they lacked the tools to determine how PCP affected the brain until 1979, when they found that it blocked a glutamate receptor, called the NMDA receptor, that is at the center of the transmission of nerve impulses in the brain.
The PCP finding led a few scientists to begin researching glutamate’s role in psychosis and other brain disorders. By the early 1990s, they discovered that besides triggering the primary glutamate receptors — NMDA and AMPA — glutamate also triggered several other receptors.
They called these newly found receptors “metabotropic,” because the receptors modified the amount of glutamate that cells released rather than simply turning circuits on or off. Because glutamate is so central to the brain’s activity, directly blocking or triggering the NMDA and AMPA receptors can be very dangerous. The metabotropic receptors appeared to be better targets for drug treatment.
The article talks about some of the new drugs in development, and the fact that this is where drug companies are placing their (quite substantial) bets at the moment.
Link to NYT article 'Daring to Think Differently About Schizophrenia'.
The American Academy of Neurology are now doing fortnightly super-geeky podcasts that feature discussions about studies published in their journal.
If you're not familiar with the arcane language of neurology - tough luck, as they make no effort to explain anything to the uninitiated.
They're not quite as bad as the American Journal of Psychiatrypodcasts (which I previously described as an 'excessively thorough lecture given by a voice synthesiser' although I'm actually finding the fembot voice rather sexy - is that wrong?) and include some discussion rather than just spoken summaries.
Occasionally, they throw a curve ball and include poetry, or a quick hint or tip for the clinician, but mainly they're neurologists doing what neurologists do best - talking about brain disorders in lots and lots of detail.
Also, I challenge you not to shout out "Space. The Final Frontier!" when you hear the opening fanfare.
I keep mentioning them, but the Royal College of Psychiatrist'spodcasts are excellent - dealing with the nitty gritty of the science but also explaining the concepts and debating the controversial points. They really should be a model for others to follow.
And as an aside, Nature'sNeuroPod seems to be missing in action again.
Mind Hacks. The Perez Hilton of academic neuroscience podcast gossip.
Neurophilosophy has found a gory but completely astonishing film of a Kisi medicine man in Tanzania performing a trepanation operation. A young lady endures the seven hour procedure that puts a hole in her skull without any anaesthetic.
Mo has been doing some fantastic work on the history of trepanation and his illustrated article on the topic is a must read if you want an overview of this ancient procedure.
This film emphasises the importance of the operation in some cultures and highlights quite what a remarkable, if not, somewhat hazardous procedure trepanation really is.
And by the way, if you saw our recent rather whimsical post on 'brain hats', the end of the video gives a whole new meaning to the phrase.
Link to video of Kisi trepanation. Link to illustrated history of trepanation.
Developing Intelligence has a fantastic post on what pharmacology and neuropsychology has told us about getting optimally wired on caffeine.
In small amounts, caffeine boosts mental function, and the article looks at scientific studies that have told us which are the optimal doses, which psychological abilities are most affected and what you can take with caffeine to modulate its effect.
Obviously, caffeine has its health risks. Psychologically speaking, even everyday doses run the risk of withdrawal symptoms and have the tendency to increase anxiety, so as with any drug, it's important to educate yourself so you can judge the risks for yourself.
The Wikipediapage on caffeine is wonderful, so it's a great complement to the fantastic round-up of stimulation-related tips from Developing Intelligence.
Link to article 'A User's Guide to Getting Optimally Wired' (via BadScience). Link to Wikipedia page on caffeine.
This case report from a 2001 study describes a patient with persistent headaches who experienced 'phantom teeth' - the sensation of non-existent vampire-like teeth in her mouth.
'Phantoms' are often the result of having a limb or other appendage removed and can affect almost any part of the body (indeed, phantom penises have been reported in the medical literature).
In this case phantom teeth seem to have occurred after surgical removal of the gums, although this case is particularly interesting because the phantoms are for teeth that were never there in the first place.
Phantoms are thought to arise when the brain's map of the sensory areas becomes distorted during re-organisation, after the actual sensations from the removed appendage stop.
A 52-year-old woman was referred to a neurologist because of right facial pain radiating from the malar region diagonally to the right upper lip area. She had pain for several months following upper and lower surgical resection of hypertrophic gums. The pain was severe, constant, and interfered with her sleep. She had no gustatory sweating or flushing of her face or neck. She developed symptoms of depression because of the chronic pain...
She reported a constant sensation of having two long extra upper canine teeth growing in front of her normal canines that felt like they were pressing on her tongue. The sensation was experienced as someone with vampire-like long upper canines ("Dracula's teeth")...
There was no family history of gum hyperplasia or supernumerary teeth. She complained of poor taste, forgetfulness, sleep fragmentation, and high-pitched ringing noises in her ears of long-standing. She had no burning of her tongue.
Today's edition of Nature has some commentary from scientists responding to their recent feature on 'optimising' the healthy brain with pharmaceutical drugs.
I suspect the letters have been edited a little though, as the first, from developmental psychologist James M. Swanson and neurobiologist Nora Volkow (who is also director of the National Institute on Drug Abuse) seems to suggest that enhancement drugs risk being addictive because:
...cognitive enhancers such as the stimulants methylphenidate (Ritalin) and amphetamine amplify the activity of dopamine, a neurotransmitter that increases saliency, making cognitive tasks and everyday activities seem more interesting and rewarding. This learned experience can lead to abuse of the drug and to compulsive use and addiction in vulnerable people.
These drugs are widely used for cognitive enhancement, but the issue is hardly new as these are relatively old drugs that almost solely target the dopamine system, whereas the newer 'cognitive enhancement' drugs (most notably modafinil) work in a quite different way (modafinil alters dopamine, among other effects, but it's hardly comparable).
Hence, they do not have the same pharmacological potential for abuse and simply aren't found to be as addictive as the amphetamines in the 'real world'.
In fact, when the Nature article asked the hypothetical question whether you would take an enhancing drug if it had no side effects, it was almost certainly inspired by modafinil.
While the drug isn't side-effect free (several are common) it tends to be significantly less risky than your typical high-charge dopamine agonist such as amphetamine, which can cause cardiovascular problems and psychosis to name but a few of its dangerous effects.
That issue aside, one of the most interesting points is made in a letter from philosopher Nick Bostrom who argues that drug companies should be allowed to develop enhancement drugs without having to specify an illness to treat.
He argues this is because the current system demands that drugs are licensed for a specific disorder, which means new disorders get invented ('disease mongering') as a way of legitimising the sale of drugs which are helpful but for less serious problems of living, such as low-level anxiety, persistent tiredness or normal memory decline, but are not significant medical treatments.
So maybe the solution to the drug companies warping medicine is to allow them to sell drugs as 'tonics', rather than medications. Certainly food for thought.
There's several other responses on the ethics and experiences of cognitive enhancement from some of the leaders in the field, so well worth a look through.
It's not often a children's book on hallucinogenic drugs gets written, but this seems to be one of those occasions. Matt Hutson has scanned in some remarkable pages from exactly such a book, published in 1991.
Apparently it's quite comprehensive, covering everything from neurons to shamans, and is also full of funky illustrations.
The prose is lucid, but the pictures crack me up. Take the cover. Look kids, in a drug free zone, you can do all kinds of things, like play tic-tac-toe. Or even watch people play tic-tac-toe! And remember, friends don't let friends wear non-footie pants.
In some cases the book might be counterproductive: "Have you ever looked at yourself in an amusement park mirror? Look what happened to you! Now, try to imagine that the whole world looked that way to you." Awesome! Where can I get some?
Link to Silver Jacket on 'Focus on Hallucinogens'.
Memoirs of a Postgrad has got a great write-up of a new low-power MRI machine, the technology that does most of the structural and functional brain scans. Even the smaller MRI machines need huge electromagnets, but this new technology uses magnets thirty thousand times weaker to image the brain.
In a standard MRI machine, a strong magnetic field is used to align the proton in each of the hydrogen atoms before using an RF pulse to knock them out of alignment. As they snap back into alignment with the magnetic field, they emit a signal which can be detected and used to create a 3D image. In the new version, the very small magnetic field isn't enough to align the protons, so a short duration (1 second) magnetic pulse of slightly higher magnitude (30 millitesla).
The resulting signals are very small, so an array of highly sensitive magnetometers are used (so-called superconducting quantum interference devices, or SQUIDS). A hugely important additional advantage of using these SQUIDS is that they are also used in the MEG (magnetoencephalography) imaging technique. This potential for MRI and MEG using the same machine raises the intriguing possibility of producing simultaneous structural images (using the MRI) and brain activation maps (using the MEG).
Unfortunately, the use of SQUIDs dashes any hopes of making the machines much smaller.
The SQUID sensors need to be extremely cold (working at approximately -170 degrees C) and so are usually bathed in liquid nitrogen, meaning a huge insulated tank sits atop the scan area.
IEEE Spectrum magazine has an article with some images from the new type of scanner, which look pretty fuzzy at the moment, but apparently can better distinguish tumours in the brain and will undoubtedly become clearer as new software is developed.
Link to Memoirs of a Postgrad post. Link to IEEE Spectrum article.
Depression, antidepressants and the 'low serotonin' myth:
Bad Science has a fantastic article on antidepressants and the widely-promoted but scientifically unsupported 'low serotonin theory' of depression.
Owing to a huge advertising push by drug companies, not only the 'man on the street', but also a surprisingly large numbers of mental health professionals (clinical psychologists, I'm look at you) believe that depression is linked to 'low serotonin' in the brain.
The only drawback to this neat sounding theory is that it is almost completely unsupported by empirical evidence or scientific studies.
Experiments that have deliberately lowered serotonin levels in the brain have found that it is possible to induce 'negative mood states' (usually milder and as short-lasting as a slight hangover), but these do not even begin to compare to the depths of clinical depression.
In terms of patients with the clinical mood disorder itself, not a single study has found a link to reduced serotonin.
Bad Science neatly reviews the science, and also discusses a new research study which chased up journalists that propagated the myth to ask for their sources.
Needless to say, none of them had any sound scientific basis for their claims.
This is not to say that antidepressants don't help treat depression, (evidence suggests they do - although the effect is more modest than drug companies would have us believe), or that neurobiology isn't important (by definition, if it's a change in thought and mood, it's a change in brain function).
If you're interested in the history of how the 'low serotonin hypothesis' came to be thought up and then subsequently promoted, despite the lack of evidence, Professional Psychology: Research and Practice recently published a great article on the topic [pdf].
Link to Bad Science on the serotonin myth. pdf of article on the history and popularity of the myth. Link to excellent PLoS Medicine article on evidence and adverts.
SciAm's Mind Matters blog has a completely fascinating post on the common assumption that humans have the the most complex brain of all the animals. Compared to a whale, however, our brain is smaller and has even less cortical folds. Does that mean they're smarter?
The article is by neuroscientist R. Douglas Fields and takes a comparative look at brain size, relation to body size, and function across the species.
It turns out, we're perhaps not quite so special as we like to believe. Even on the ratio of brain to body size, humans are beaten by the humble tree shrew.
We humans pride ourselves on our big brains. We never seem to tire of bragging about how our supreme intelligence empowers us to lord over all other animals on the planet. Yet the biological facts don't quite square with Homo sapiens' arrogance. The fact is, people do not have the largest brains on the planet, either in absolute size or in proportion to body size. Whales, not people, have the biggest brains of any animal on earth.
Just how smart are whales? Why do they have such big brains? Bigger is not always better; maybe the inflated whale brain is not very sophisticated on a cellular level. We're closer to answering such questions now, for a couple of recent papers address them squarely. What they find is helping separate fact from fiction.
It turns out that while whales have bigger brains, humans have more neurons. Nevertheless, whales have more glial cells.
Glial cells were traditionally thought to do nothing more than support and insulate the neurons, but it's becoming increasingly clear that they're actually part of the brain's processing system (although they're exact role is far from clear).
So maybe there's a lot more to the whale brain that it first appears.
I've just discovered a wonderfully simple finger touch procedure that can test the function of your corpus callosum, a key brain structure that connects the two cortical hemispheres.
It is called the 'cross lateralization of fingertips test' and was used in a 1991 study by Kazuo Satomi and colleagues.
It relies on the fact that different hemispheres are responsible for the movements and sensations from each hand.
In other words, each hand is connected to a different side of the brain, and, to allow you to co-ordinate both hands, the brain passes information between the two sides by using the corpus callosum.
The corpus callosum is the largest structure in the brain and works like a huge bundle of white matter 'cables', connecting different areas.
If this structure gets damaged, a patient might have trouble with coordinating their hands, preventing them from matching sensations on one hand with movement on the other, because the information doesn't get to where it's needed.
The test works like this: you need to ask someone to close their eyes and put their hands face up.
You then touch one of their fingertips with a pencil, and with the opposite hand the participant needs to touch the corresponding finger with thumb of the same hand.
For example, if you touched their right ring finger, they would need to touch their left ring finger with their left thumb, as shown in the diagram above.
You need to do this on both hands, with them always touching the corresponding finger on the opposite hand.
It's important that the person keeps their eyes closed, because as soon as they look, they get information from the eyes, which goes to both hemispheres.
Patients who have damage to the corpus callosum (either because of acquired damage or because it just hasn't developed) usually can't do this test, because of the disruption in communication between the two hemispheres of the brain.
Of course, just to be sure its not a problem with movement or sensation in one hand only, the patient is also asked to do another quick test where they're asked touch the exact finger you just touched.
For this part, the sensation and movement happen in the same hand, so information doesn't need to cross the corpus callosum.
The test was shown to me by Dr Emma Barkus, who researches what neurological tests can tell us about psychosis and unusual experiences.
Link to Wikipedia page on the corpus callosum. Link to abstract of Satomi and colleagues study (thanks Emma!).
This is a completely amazing case report published in Acta Neurochirurgica about a man who managed to get a paintbrush stuck in his brain during a fight.
The most astounding thing is that from the outside it only looked like he had a tiny cut on the eye.
Artistic assault: an unusual penetrating head injury reported as a trivial facial trauma.
Mandat TS, Honey CR, Peters DA, Sharma BR.
The authors report a case of penetrating head injury that presented with a deceptively mild complaint. To our knowledge, it is the first report of a paint brush penetrating the brain. The patient reported being punched in the left eye and presented with a minor headache, swelling around the left orbit, a small cut on the cheek and slightly reduced left eye abduction. After radiological evaluation, a penetrating head injury was diagnosed.
Under general anesthesia, through a lateral eyelid incision a 10.5 cm long paint brush, which had penetrated from the left orbit to the right thalamus, was removed. No post-operative infection was seen at six months follow-up. This brief report serves to highlight that penetrating brain injury can occur without neurological deficit and that a minimally invasive surgical approach was successful in avoiding any complications.
I've just found a page with some beautiful pictures of antique neurosurgery tools, including these trephining or trepanning tools for cutting holes in the skull. Can you imagine the elbow work needed to get the job done?
After a bit of a search I discovered that there's a healthy market in neurosurgical tools on the net, old and new.
Advances in the History of Psychology discovered an antique trepanning brace that's currently for sale for a cool $1900.
One antique dealer even has a receipt for a trepanning operation from 1814. It turns out you could get your head drilled for $20 in early 19th century Massachusetts.
If you're after some more modern kit, it turns out you can pick up quite a few contemporary surgical tools on eBay.
Including this VectorVision2 BrainLab system, a snip (excuse the pun) at $15,000.
The VectorVision2 is an 'augmented reality' image guidance system (sometimes called frameless stereotaxy) that allows the surgeon to see where his tools are in relation to both the patient and a matched brain scan image - while the operation is in progress.
While the tools can be bought and sold online, most of the anaesthetics are, of course, controlled drugs.
So while you may be able to get the latest high-tech kit on eBay, you're still going to have to resort to those traditional 19th century surgical painkillers: brandy, and a stiff upper lip.
Link to pictures of antique neurosurgery tools. Link to VectorVision2 for sale on eBay.
Treatment Online has an interesting piece on the development of a cocaine vaccine. Unlike other drugs that reduce the pleasurable effect of addictive drugs, this is genuinely a vaccine - it persuades the immune system to attack cocaine molecules.
There are various drugs that are sometimes described conveniently, but inaccurately, as 'vaccines' for addictive substances.
For example, disufiram (aka Antabuse) creates a severe hangover 10 minutes after taking any alcoholic drink by inhibiting certain enzymes in the liver which break down alcohol. The idea is that it acts as an instant form of aversion therapy.
A drug called naltrexone blocks opioids in the brain which all pleasurable drugs trigger, either directly (in the case of heroin), or indirectly (in the case of alcohol). Naltrexone simply aims to reduce how 'fun' the drug is, leading to extinction of the link between the drug and the 'high'.
However, neither of these are actually 'vaccines' in the proper sense of the word.
Vaccines are substances that stimulate the immune system. The immune system identifies and adapts to the key features of the potentially dangerous invader, and works to destroy it.
Of course, this happens when foreign pathogens (like diseases) enter the body, but the immune system can be triggered by safe or less dangerous substances that share the 'key features' with the more dangerous disease. This safe or less dangerous substance is the vaccine.
Edward Jenner invented the procedure after working out that giving people a tiny amount of the non-lethal cowpox virus vaccinated them against the deadly smallpox virus. In fact, this is where the word 'vaccinate' comes from as 'vacca' means cow in Latin.
The developers of the new cocaine vaccine, known as 'TA-CD', are doing essentially the same thing by cleverly combining a deactivated cocaine molecule with a deactivated cholera toxin molecule.
The deactivated cholera toxin is enough to trigger the immune system, which finds and adapts to the new invader.
Because the cholera toxin and the cocaine molecule are combined, the immune system also adapts to the key features of cocaine, so works out how to seek and destroy cocaine molecules.
This means they never reach the brain in sufficient quantities to cause an effect.
A key advantage is that unlike other anti-addiction drugs, which have to be in the body to have their effect, the cocaine vaccine permanently changes the immune system to neutralise cocaine.
Of course, it may not be completely effective, or it may not work in all people, but that's the aim.
The drug is about to studied with a Phase III clinical trial to see if it useful in treating cocaine addiction, after which, if it is shown to be safe and effective, it could be approved for widespread use.
Unlike the current concerns about the supposed 'new ethical challenges' of medical therapies being used by healthy people (which, as we've noted, are actually as old as drugs themselves), this therapy may present a relatively new ethical dilemma.
If effective, you can see that some parents might want to vaccinate their non-addicted, perfectly healthy children, so they are 'immune' to cocaine.
The difference here, is that once given, the 'immunity' may be permanent. In other words, you would make the decision that your child will never be able to experience the effects of cocaine for the rest of their life.
One interesting effect might be an 'arms race' between illicit drug producers and vaccine makers. As children become 'vaccinated' against the common drugs of abuse, the market for street drugs would fragment and diversify into drugs that don't have vaccines yet.
A Brave New World indeed.
Link to Treatment Online on cocaine vaccine. Link to PubMed papers on cocaine vaccine. Link to Toronto Globe and Mail article on the vaccine.
BBC News has a report on the increasingly popularity of gamma-Butyrolactone or GBL as a recreational drug. Actually, it's not a drug in itself, but once ingested it is metabolised into GHB, a drug often sold under the name 'Liquid Ecstasy'.
Actually, the effects are much more like alcohol than ecstasy (the street name is just a marketing ploy) and the similarities to alcohol can be seen in its structure and effect on the brain, as both affect GABA receptors.
The increasing popularity of GBL is particularly interesting, however, as GBL is legal, but the body transforms it into the illegal UK Class C substance GHB.
Compounds that are weak or inactive until the body transforms them into an active drug are called prodrugs, and this is the first situation that I can think of where a legal prodrug has been found for an illegal drug.
Probably the most commonly used illicit prodrug is heroin, which is metabolised into morphine in the body, but both are Class A drugs in the UK so there's no legal benefit to having one rather than the other.
GHB is usually described as a 'date rape drug' despite the fact that it is barely used in 'date rapes', unlike alcohol, which is used in the vast majority of cases and is a much better candidate for the 'date rape drug' label.
GBL is closely related to 1,4-Butanediol, which is also a GHB prodrug. 1,4-B recently caused a scare because a toy called 'Aqua Dots' was made using the compound and had to be withdrawn after several infants swallowed the plastic pellets and became dangerously intoxicated.
Needless to say, the news inspired some to swallow the plastic pellets for fun and the experience was, inevitably, reported online.
GHB is a nervous system depressant, and like all depressants, a major danger is unconsciousness, coma, and collapse of breathing and circulation.
Consequently, there have been a number of reports of these cases being admitted to hospital emergency rooms.
The long-term toxicity of these substances aren't really known, but as both GBL and 1,4-B are used as industrial solvents and cleaning fluids, it's likely that they give the body a fairly rough time.
Sam Harris is better known as a leading atheist, but he's also completing a PhD in cognitive neuroscience and a forthcoming study by Harris is a flawed but important contribution to how we understand the neuropsychology of belief.
Harris and his colleagues asked participants to respond to a number of statements with buttons presses indicating that they either believed, disbelieved or were undecided about each proposition.
The participants were shown statements relating to mathematics, geography, word meaning, general knowledge, ethics, religion and their own life.
While they were doing this brain activity was measured by a fMRI scanner, with a view to finding out which areas of the brain were involved in 'belief' and 'belief states'.
It's a straightforward study and you may wonder why no-one has ever done it before. It's possibly because, from what we know about belief, it's not clear that this study tells us much more about belief rather than what happens when people respond to questions.
Belief is a concept that is used all the time in psychology but is a pain to define in a way that science would be happy with. If you're not convinced Eric Schwitzgebel's guide to the problem is about as good as you're likely to read, but I'm going to give a quick run through of the most relevant issues here.
One of the main problems is that experimental neuropsychology relies on measuring brain and behaviour during activities, and there is no single activity that represents 'believing'.
When do you believe Paris is the capital of France? Only when you think about it or all the time? Presumably, we believe it all the time as we don't assume someone has stopped believing it when they think about something else or are unconscious, when asleep perhaps.
The above example treats belief as a proposition stored in memory (a semantic memory in psychology parlance), but you can easily respond to a belief question if you've never thought about a proposition before in your life.
Do you believe tigers wear pink pyjamas? Presumably you don't, but it's unlikely you've ever thought about this before. It's an answer reconstructed from fragments of other information you have in memory, reasoning and 'gut instinct' to varying degrees.
Saying you believe something can work the same way, of course. You may never have thought about it before, but you can say you believe it.
Just these two examples show that saying you believe or disbelieve can involve retrieving a 'fact' from memory, or might involve any number of other mental processes to give an answer.
Furthermore, its not even clear that two people retrieving facts from memory are even thinking about the same thing.
Here's another question. Do you believe snow is white? Imagine two people are asked this question. One believes snow is frozen water, the other believes it's star dust.
Considering that each person believes that the subject is something completely different, are they answering the same belief question, or is one answering 'I believe frozen water is white' while the other is answering 'I believe stardust is white'? Now scale that up to concepts like democracy or religion.
This is known as the atomism vs holism debate in philosophy and concerns whether we can ever consider belief is isolation ('snow is white'), or whether we can only consider them in relation to other beliefs that might need to be accessed at the same time (what we believe a word represents, or, even, what we believe the about what we believe).
These issues are essential for neuropsychologists, because they predict different patterns of brain activity, even though the behaviour (e.g. responding 'I believe') is exactly the same.
The point of having so many topics in Harris study is that despite these issues, on average, there might be some brain differences involved in answering 'believe' or 'disbelieve' regardless of the topic, but the mental processes involved in answering these questions might be so diverse that it's difficult to say whether the average brain activity actually describes 'belief' in any meaningful sense.
This doesn't mean the study is worthless though, and in fact, it's an essential step in the scientific study of belief.
Science tends to start big, obvious and practical, and work through objections, new ideas and problems over time with new experiments. This study is one of the early but essential, big, obvious and practical steps.
Interestingly, some philosophers (known as eliminative materialists) argue that the concept of belief is just one we've inherited from everyday or 'folk psychology' and because of the conceptual problems with it, we'll eventually realise there are no distinct mind or brain process that can be coherently identified as 'belief'.
Like the concept of 'rooting for your team', we'll just realise its too broad to be scientifically useful and we'll disregard the idea of 'belief' mechanisms in the brain in favour of a variety of better specified concepts that reliably map onto mind and brain processes.
Importantly, studies into the neuropsychology of belief, like this one, can help answer these questions, and eventually, they are likely to have profound implications for everything from lie detection to clinical medicine.
Link to full-text of Harris's study. Link to Schwitzgebel's on belief for the Encyclopaedia of Philosophy. Link to write-up from Time.
The Children's Hospital Boston have created a fantastic 'virtual neuron' which allows you to explore the basics of neural transmission with an interactive flash demo.
Strictly speaking, of course, it's designed for children, but it's remarkably good fun whatever your age.
Once you've got the demo window up, the options at the top of the screen allow you to choose different demonstrations, and the text below explains what's happening.
Man hammers nail into head every week for 11 weeks:
I just found this jaw-dropping case study of a man who banged 11 nails into his head while sadly quite distressed and psychotic.
The X-ray images are striking on their own, and what is even more astounding is that he made a full recovery.
Penetrating head injury in planned and repetitive deliberate self-harm.
Mayo Clinic Proceedings. 2007 May;82(5):536.
Demetriades AK, Papadopoulos MC.
44-year-old man presented to his local emergency department wearing a baseball cap and complaining of headaches that had progressively worsened over the preceding 11 weeks. After we provided generous analgesia and performed simple investigations that failed to identify a diagnosis, the patient removed his cap to reveal an assortment of metallic objects embedded in his scalp. Plain radiographs showed 11 nails penetrating into his brain. A detailed history revealed a diagnosis of paranoid schizophrenia, and the patient confirmed that he had hammered a nail into his head each week for the past 11 weeks to rid him of evil. The nails were removed with the patient under general anesthesia, and he made an uncomplicated recovery with no neurological deficits.
Today's Nature has a great article [pdf] on the neuroscience of psychopaths, as investigated by an ingenious study being run by a group of Dutch researchers.
Although there is a higher number of psychopaths among violent criminals, a psychopath is not necessarily someone who is violent.
The term describes someone who is considered to lack empathy or conscience, is superficially charming, manipulative, has 'shallow affect' (doesn't have a big emotional range) and has poor impulse control.
More recently, psychopathy has become synonymous with the use of the PCL-R, the diagnostic tool also known as the Hare Psychopathy Checklist after it's creator and psychopathy researcher Robert Hare.
The Dutch team, however, are working with psychopaths who are in prison for presumably quite serious crimes, precisely because they lack empathy.
They are comparing the brain activation between psychopaths and non-psychopaths when they view material that communicates emotions and normally evokes an empathy-driven reaction.
By looking at which areas are less active in the presumably empathy-less psychopaths, they hope to find out the crucial empathy-related brain circuits.
There are more details about the study in the article, but one bit is particularly interesting, where one of the participants, from a high security prison, comments on the study:
When he entered the prison five years ago, Boerema says, 'borderline personality' was the fashionable term, and his designated pigeonhole. "The psychopathy label is more damaging though — it prompts everyone to see you as a potential serial killer, which I could never be." (Note, in reporting this article it was agreed that inmates' crimes would be neither asked about nor reported on.) But Boerema also wears the score as a badge of honour: "I think my high psychopath score is a talent, not a sickness — I can make good strong decisions, and it's good to have some distance with people."
Interestingly, Boerema (not his real name) makes a couple of points that have also been made in the psychological literature.
Ian Pitchford proposed in a 2001 article that psychopathy could be an evolutionary advantage for a minority of individuals, as it allows them act violently or antisocially without any emotional cost to themselves.
Furthermore, discussion in both the psychological and legal literature has focused on whether labelling someone a 'psychopath' is unjustly stigmatising.
One article even goes as far as to suggest that 'psychopathy' is just a modern term we've invented to replace the world 'evil'.
The Neurocritic has compiled a collection of interesting neurological studies where a number of patients seems to have experienced a profound change in their sexual preferences as a result of brain disturbance.
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