Splintered sexuality as a window on the brain

Carl Zimmer has an interesting article in Discover Magazine on brain function and sex, one of the most neglected areas in contemporary neuroscience.

We know scandalously little about the neuroscience of sex. For example, we know more about the what the brain does during hiccups than during orgasm and yet very little sex research is completed in comparison to studies on other areas of human life.

Zimmer focuses on several recent neuroimaging studies on sexual desire and contrasts it with some case studies of altered sexuality after brain damage, particularly one of the first from 1945 – a patient named CW who showed a sharp increase in sexual desire associated with epileptic seizures.

Curiously though, the article implies that, in sex research, brain imaging is the way forward while case studies of brain damaged patients are a thing of the past, when this couldn’t be further from the truth.

We have learnt far more about the link between brain circuits and human behaviour through studying patterns in what people can and cannot do after brain injury than we ever have through brain scans.

This is because scans can only tell us that activity is associated with a behaviour whereas studies of brain injury tell us whether the affected part of the brain is necessary for the function we’re studying.

Think of it like this: if you didn’t know how a car worked and wanted to work it out from scanning from the outside, seeing what parts were active when it moved would likely also identify the radio along with the engine.

But if we looked at a bunch of differently damaged cars we would be able to quickly work out that the radio was non-essential for driving because when it was damaged, the car could still move, whereas damage to the engine stopped it dead.

The same goes for sex research and as described in a recent scientific article on what altered sexual function after brain damage tells us about sexuality, ‘lesion studies’ have taught us a great deal, whereas the relatively few brain scanning studies are still just scratching the surface.

Both are important, of course, and there are advantages to each. Zimmer gives the example of an EEG study showing the progression of activity through the brain during sexual desire, something not possible just from studies of damage.

Nevertheless, researching brain dysfunction is still our most useful tool and one that has taught us the most about the neuroscience of human sexuality.

Link to Discover article ‘Where Does Sex Live in the Brain?’
Link to article on what brain damage tell us about sex.