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Thursday, October 30, 2008

fMRI Reveals True Nature of Hatred

Given that I've taken to calling myself Neuroskeptic, I feel it's time to take a skeptical line on some neuroscience. Fortunately, an ideal example has just popped up. The paper, ominously titled "Neural Correlates Of Hate", was published in the open-access journal PLoS One. It's been picked up by the major science news sites and various newspapers, with headlines generally some variation of
Brain's 'hate circuit' identified

Those of us who keep up with the news won't be surprised. It seems like every week, reports come in that scientists have discovered the brain circuit for something.

By and large, these reports are nonsense. I will now explain why, and then tell you my theory of why everyone is so fascinated by neuroscience (and especially neuroimaging), before finishing by explaining why people aren't actually interested in neuroscience at all. Nice twist, eh? First, I'd like to make it clear that I'm not out to criticize the paper itself or the authors, Dr. Zeki and Dr. Romaya. No doubt the methodology of the experiment could be critiqued, but this is true of all such research, and I think the data from this study are valuable and interesting - to a specialist. What concerns me is the way in which this study and others like it are reported, and indeed the fact that they are repored as news at all.

So what did the authors do? They posted some adverts and recruited seventeen healthy volunteers. They showed them photos, which the volunteers had previously sent them. Some of the photos were of someone who the volunteer really hated - generally either ex-lovers or work rivals, predictably enough. Others were of people that the volunteer knew, but had "neutral feelings" towards. This was an fMRI study, so the whole process took place inside an MRI scanner configured to measure changes in blood oxygenation levels across the brain (which is considered a proxy for metabolic activity, itself a proxy for neural firing.) They then calculated which areas of the brain showed greater oxygenation changes when people were looking at their own personal hate figures than at the other faces. They found several areas in which the difference was statistically significant, which is what the yellow areas on this picture represent:

(Taken from Zeki & Romaya PLoS One 2008, without explicit permission)

This is all very well and good. Some people take a skeptical line on the whole business of fMRI, and they would probably consider these blobs-on-the-brain to be pretty much meaningless. I'm not one of them - I think these data tell us something about the human brain, although only in the context of other research, and only when the limitations of fMRI are borne in mind. (I hope to expand on my views of fMRI soon.) This is one piece of a big puzzle.

But one thing is clear, the brain's "hate circuit" is nowhere to be found in this study. This phrasing doesn't appear in the paper: it seems to have originated in the university press release (as this kind of stuff generally does.) What this data shows is that certain parts of the brain become more active when people are looking at pictures of people that they hate, and presumably therefore experiencing the emotion of hatred. These areas are not only activated by hatred; the putamen, for example, is known to be involved in the control of all movements. Every area which lit up in this study has lit up in a hundred other experiments which have nothing to do with hate. It's not as if scientists have just found a new bit of the brain tucked away somewhere, which turns out to be the root cause of all human evil. (Which is a pity, because that would look great on a grant application.)

Now, given that, I really can't see why anyone but a professional neuroscientist would want to know which parts of the brain activate when you look at pictures of a hated rival, not least because most laymen wouldn't know their putamen from their parietal lobe. (That's like saying "arse from their elbow," for non-neuroscience geeks.) And there's no reason they should. Neuroanatomy is very difficult, as any undergraduate neuroscientist knows. The brain is just an organ. It has various parts. Some people, like me, spend our lives trying to figure out how it all works, and we would say that it's very interesting. Of course, we would say that, because the brain pays our bills. To anyone else, it's just a grey lump.

Except, of course, that it's not. People are fascinated by the brain. We can't get enough cognitive neuroscience and fMRI images. They're a staple of the newspaper science pages. Does this mean people are interested in neuroscience? No. People don't understand neuroscience, because it's bloody hard. What interests people is not specific findings about the brain but the fact that science is "discovering things" about the brain and by implication, human life. At the back of all of our minds is the exciting feeling that whenever scientists find "the circuit" associated with some emotion or some behavior, an important truth about human nature has been revealed. (Neuroscientists get this feeling too, but we know it's more complicated than that. Some of us anyway.)

Sometimes this feeling surfaces and is expressed in words. Terence Kealey is a biochemist and head of the UK's only private University, The University of Buckingham. He's known for his libertarian politics. About a year ago he penned a profoundly revealing article for the Times. I would encourage you to read it, but you might need a dangerously large spoon of salt. Essentially, Kealey reads an fMRI study in which social science students were able to donate money to charity, and thinks it proves that
...people like being taxed for charity, but they like giving money to good causes even more... [which] challenges so many political assumptions. First, it disproves the Left’s belief that only the state will succour the poor: actually, philanthropy is hardwired into our brains and, in the absence of state aid, private giving is biologically determined...
Nothing in this paragraph is implied by the brain images which Kealey is talking about. Not a word. It's really quite impressively divorced from reality. In particular, there is absolutely no good reason to think that because a certain part of the brain is activated when we do something, that thing is "hardwired" or "biologically determined". This is because the brain is the organ of learning, and if we learn to do something, some part of the brain will be involved in that learning. Neuroimaging has very little to do with the nature / nurture debate. But my goal is here is not to bash Terence Kealey. Well to be honest it is a bit, but the main point is that the mistake that Kealey makes - seeing fMRI as a way of investigating the roots of human behavior - is very common.

The idea of a "hate circuit" is beguiling, I think, because it seems to show that hatred is a deep-seated human emotion with a biological basis. Personally, I think that's probably true. But I don't think that because of brain scans. I think that because I read the news and I read history. People across the world have been hating other people, in depressingly stereotypical ways, for as long as we can determine. That's human nature, but brain scans don't tell us anything about that. They tell us about the brain, which is a grey lump. Some of us have a professional interest in grey lumps, but everyone else would learn much more about hatred by going to see some Shakespeare or reading a history of the Balkans or something.

To sum up, neuroimaging and neuroscience in general are fascinating in their own right, but highly technical. As such there's no good reason why lay people should be any more interested in them than they are in chemistry. Given that they are in fact very interested, logically there must be bad reasons for this, such as the mistaken belief that brain scans can tell us about human behaviour, human nature, or everyday life. They don't and they probably can't. Vulgarized neuroscience now takes the place that Freudianism did 30 years ago, in that it offers simplistic, mechanistic explanations for complex behaviours, whose only claim to credibility is that they are "scientific". This kind of thing does real neuroscience, including fMRI, no favours.

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