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Thursday, October 28, 2010

Brain Scans Prove That The Brain Does Stuff

According to the BBC (and many others)...
Libido problems 'brain not mind'

Scans appear to show differences in brain functioning in women with persistently low sex drives, claim researchers.

The US scientists behind the study suggest it provides solid evidence that the problem can have a physical origin.

The research in question (which hasn't been published yet) has been covered very well over at The Neurocritic. Basically the authors took some women with a diagnosis of "Hypoactive Sexual Desire Disorder" (HSDD), and some normal women, put them in an fMRI scanner and showed them porn. Different areas of the brain lit up.

So what? For starters we have no idea if these differences are real or not because the study only had a tiny 7 normal women, although strangely, it included a full 19 women with HSDD. Maybe they had difficulty finding women with healthy appetites in Detroit?

Either way, a study is only as big as its smallest group so this was tiny. We're also not told anything about the stats they used so for all we know they could have used the kind that give you "results" if you use them on a dead fish.

But let's grant that the results are valid. This doesn't tell us anything we didn't already know. We know the women differ in their sexual responses - because that's the whole point of the study. And we know that this must be something to do with their brain, because the brain is where sexual responses, and every other mental event, happ

So we already know that HSDD "has a physical origin", but only in the sense that everything does; being a Democrat or a Republican has a physical origin; being Christian or Muslim has a physical origin; speaking French as opposed to English has a physical origin; etc. etc.
None of which is interesting or surprising in the slightest.

The point is that the fact that something is physical doesn't stop it being also psychological. Because psychology happens in the brain. Suppose you see a massive bear roaring and charging towards you, and as a result, you feel scared. The fear has a physical basis, and plenty of physical correlates like raised blood pressure, adrenaline release, etc.

But if someone asks "Why are you scared?", you would answer "Because there's a bear about to eat us", and you'd be right. Someone who came along and said, no, your anxiety is purely physical - I can measure all these physiological differences between you and a normal person - would be an idiot (and eaten).

Now sometimes anxiety is "purely physical" i.e. if you have a seizure which affects certain parts of the temporal lobe, you may experience panic and anxiety as a direct result of the abnormal brain activity. In that case the fear has a physiological cause, as well as a physiological basis.

Maybe "HSDD" has a physiological cause. I'm sure it sometimes does; it would be very weird if it didn't in some cases because physiology can cause all kinds of problems. But fMRI scans don't tell us anything about that.

Link: I've written about HSDD before in the context of flibanserin, a drug which was supposed to treat it (but didn't). Also, as always, British humour website The Daily Mash hit this one on the head.

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