Lessons from the Video Game Brain

See also Lessons from the Placebo Gene. Also, if you like this kind of thing, see my other fMRI-curmudgeonry(1, 2)

The life of a neurocurmudgeon is a hard one, but once in a while, fate smiles upon us. This article in the Daily Telegraph neatly embodies several of the mistakes that people make about the brain, all in one bite-size portion.

The article is about a recent fMRI study published in the Journal of Psychiatric Research. 22 healthy Stanford student volunteers (half of them male) played a "video game" while being scanned. The game wasn't an actual game like Left 4 Dead(*), but rather a kind of very primitive cross between Pong and Risk, designed specifically for the purposes of the experiment:

Balls appeared on one-half of the screen from the side at 40 pixel/s, and 10 balls were constantly on the screen at any given time. One’s own space was defined as the space behind the wall and opposite side to where the balls appeared. The ball disappeared whenever clicked by the subject. Anytime a ball hit the wall before it could be clicked, the ball was removed and the wall moved at 20 pixel/s, making the space narrower. Anytime all the balls were at least 100 pixels apart from the wall ... the wall moved such that the space became wider.

Essentially they had to click on balls to stop them moving a line. This may not sound like much fun, but the author's justification for using this task was that it allowed them to have a control condition in which the instructions and were the same (click on the balls) but there was no "success" or "failure" because the line defining the "territory" was always fixed. That's actually a pretty good idea. The students did the task 40 times during the scan for 24s at a time, alternating between the two conditions, "no success" (line fixed) and "game with success/failure" (line moves).

The results: While men & women were equally good at clicking balls, men were more successful at gaining "territory" than the women. In both genders, doing the task vs. just resting in the scanner activated various visual and motor-related areas - no surprise. Playing the game vs. doing the control task in which there was no success or failure produced more activation in a handful of areas but only "at a more liberal threshold" i.e. this activation was not statistically reliable. A region-of-interest analysis found activation in the left nucleus accumbens and right orbitofrontal cortex, which are "reward-related" areas. In males, the game-specific activation was greater than in females in the right nucleus accumbens, the orbitofrontal cortex, and the right amygdala.

These areas are indeed "neural circuitries involved in reward and addiction" as the authors put it, but they're also activated whenever you experience anything pleasant or enjoyable, such as drinking water when you're thirsty. Water is not known to be addictive. So whether this study is relevant to video-game "addiction" is anyone's guess. As far as I can tell, all it shows is that men are more interested in simple, repetitive, abstract video games. But that's hardly news: in 2007 there was an International Pac-Man Championship with 30,000 entrants; the top 10 competitors were all male. (If anything in that last sentence surprises you, you haven't spent enough time on the internet.)

Anyway, that's the study. This is what the Telegraph made of it:

Playing on computer consoles activates parts of the male brain which are linked to rewarding feelings and addiction, scans have shown. The more opponents they vanquish and points they score, the more stimulated this region becomes. In contrast, these parts of women's brains are much less likely to be triggered by sessions on the Sony PlayStation, Nintendo Wii or Xbox.

Well, not quite. No opponents were vanquished and no Wii's were played. But so far this is just another fMRI study that attracted the attention of a journalist who knew how to spin a good story. Readers of Neuroskeptic will know this is not uncommon. However, it doesn't end there. Here's the really instructive bit:

Professor Allan Reiss of the Centre for Interdisciplinary Brain Sciences Research at Stanford University, California, who led the research, said that women understood computer games just as well as men but did not have the same neurological drive to win.
"These gender differences may help explain why males are more attracted to, and more likely to become 'hooked' on video games than females," he said.
"I think it's fair to say that males tend to be more intrinsically territorial. It doesn't take a genius to figure out who historically are the conquerors and tyrants of our species – they're the males.
"Most of the computer games that are really popular with males are territory and aggression-type games."

Now this is a theory - men like video games because we're intrinsically drawn to competition, conquest and territory-grabbing. This may or may not be true; personally, in the light of what I know of history and anthropology, I suspect it is, but even if you disagree, you can see that this is an important theory: it makes a big difference whether it's true or not.

However, the fMRI results have nothing to do with this theory. They neither support nor refute it, and nor could they; this experiment is essentially irrelevant to the theory in question. Prof. Allan Reiss is simply stating his personal opinions about human nature - however intelligent & informed these opinions may be. (Just to be clear, it's quite possible that Reiss didn't expect to be quoted in the way he was; he may have, not unreasonably, thought that he was just giving his informal opinion.) The Telegraph's sub-headline?

Men's passion for computer games stems from a deep-rooted urge to conquer, according to research

There are some lessons here.

1. If you want to know about something, study it.

If you want to learn about human behaviour, study human behaviour. Stanley Milgram discovered important things about behaviour; if he had never even heard about the brain, it wouldn't have stopped him from doing that.

Neuroscience can tell us about how behaviour happens. We get thirsty when we haven't drunk water for a while. Neuroscience, and only neuroscience, will tell you how. Some people get depressed or manic. One day, I hope, neuroscience will tell us the complete story of how - maybe mania will turn out to be caused by hyper-stimulation of a certain dopamine receptor - and we'll be able to stop it happening with some pill with a 100% success rate.

However, neuroscience can't tell you what human behaviour is: it cannot describe behaviour, it can only explain it. People know about thirst and depression and mania long before they knew anything about the brain. More importantly, and more subtly, neuroscience can only explain behaviour in the "how" sense; only rarely can it tell you why behaviour is the way that it is.

If someone is behaving in a certain way because of brain damage or disease, that's one of these rare cases. In that case "damage to area X caused by disease Y" is "why". But in most cases, it's not. To say that men like video games because their reward systems are more sensitive to video games is not a "why" explanation. It's a "how" explanation, and it leaves completely open the question of why the male brain is more sensitive to video games. The answer might be "innate biological differences due to evolution", or it might be "sexist upbringing", or "paternalistic culture", or anything else.

(This is often overlooked in discussions about psychiatry. Some people object to the idea that clinical depression is a neuro-chemical state, pointing out that depression can be caused by stress, rejection and other events in life. This is confused; there is no reason why stress or rejection could not cause a state of low serotonin. By extension, saying that someone has "low serotonin" always leaves open the question of why.)

2. Brains are people too

This leads on to a more subtle point. Some people understand the difference between how and why explanations, but feel that if the "how" is something to do with the brain, the "why" must be to do with the brain too. They look at brain scans showing that people behave in a certain way because their brain is a certain way (e.g. men like games because their reward system is more activated by games), and they think that there must be a "biological" explanation for why this is.

There might be, but there might not be. Brains are alive; they see and hear; they think; they talk; they feel. Your brain does everything you do, because you are "your" brain. The astonishing thing about brains is that they are both material, biological objects, and concious, living people, at the same time.

Your brain is not your liver, which is only affected by chemical and biological influences, like hormones, toxins, and bacteria. Your liver doesn't care whether you're a Christian or a Muslim, it cares about whether you drink alcohol. Your brain does care about your religion because some pattern of connections in your brain gives you the religion that you have.

Brain scans, by confronting us with the biological, material nature of the brain, make us look for biological, material why explanations. We forget that the brain might be the way it is because of cultural or historical or psychological or sociological or economic factors, because we forget that brains are people. We tend to think of people as being something beyond and above their brains. Ironically, it's this primitive dualism that leads to the most crude materialistic explanations for human behaviour.

3. Beware neuro-fetishists

There's a doctoral thesis in "Science Studies" to be written about how it came to happen, but that we fetishize the brain is obvious. For much of the 20th century, psychology was seen in the same way. Freud joined Nietschze, Marx and Heidegger in the ranks of Germanic names that literary theorists and lefty intellectuals loved to drop.

Then the bottom fell out of psychoanalysis, Prozac and fMRI arrived and the Decade of the Brain was upon us. Today, neuroscience is the new psychology - or perhaps psychology is becoming a branch of neuroscience. (If I asked you to depict psychology visually, you'd probably draw a brain - if you do a Google image search for "psychology", 10 out of the 21 front page hits depict either a brain or a head; this might not surprise you but it would have seemed odd 50 years ago.) There's a presumption that neuroscience is key to answering both how and why questions about the mind.

Neuroscience is now hot, but what people are mostly interested in are psychological and philosophical questions. People care about The Big Questions like -

"Is there life after death? Do we have free will? Is human nature fixed? Are men smarter/more aggressive/more promiscuous/better drivers than women? Why do people become criminals/geniuses/mad?"

These are good questions - but neuroscience has little to say about them, because they're not questions about the brain. They're questions for philosophers, or geneticists, or psychologists. No brain scan is going to tell you whether men are better drivers than women. It might tell you something about the processes by which make decisions while driving, but only a neuroscientist is likely to find that interesting.

P.S It turns out that people were saying similar things about this research back in Feburary. A blogger who writes about research on video games (neat) wrote about it way back then. So why did the Telegraph decide to resurrect the story as if it were new? That's just another one of life's mysteries.

[BPSDB]

(*) Which is so awesome.

F HOEFT, C WATSON, S KESLER, K BETTINGER, A REISS (2008). Gender differences in the mesocorticolimbic system during computer game-play Journal of Psychiatric Research, 42 (4), 253-258 DOI: 10.1016/j.jpsychires.2007.11.010

Lessons from the Video Game Brain

See also Lessons from the Placebo Gene. Also, if you like this kind of thing, see my other fMRI-curmudgeonry(1, 2)

The life of a neurocurmudgeon is a hard one, but once in a while, fate smiles upon us. This article in the Daily Telegraph neatly embodies several of the mistakes that people make about the brain, all in one bite-size portion.

The article is about a recent fMRI study published in the Journal of Psychiatric Research. 22 healthy Stanford student volunteers (half of them male) played a "video game" while being scanned. The game wasn't an actual game like Left 4 Dead(*), but rather a kind of very primitive cross between Pong and Risk, designed specifically for the purposes of the experiment:

Balls appeared on one-half of the screen from the side at 40 pixel/s, and 10 balls were constantly on the screen at any given time. One’s own space was defined as the space behind the wall and opposite side to where the balls appeared. The ball disappeared whenever clicked by the subject. Anytime a ball hit the wall before it could be clicked, the ball was removed and the wall moved at 20 pixel/s, making the space narrower. Anytime all the balls were at least 100 pixels apart from the wall ... the wall moved such that the space became wider.

Essentially they had to click on balls to stop them moving a line. This may not sound like much fun, but the author's justification for using this task was that it allowed them to have a control condition in which the instructions and were the same (click on the balls) but there was no "success" or "failure" because the line defining the "territory" was always fixed. That's actually a pretty good idea. The students did the task 40 times during the scan for 24s at a time, alternating between the two conditions, "no success" (line fixed) and "game with success/failure" (line moves).

The results: While men & women were equally good at clicking balls, men were more successful at gaining "territory" than the women. In both genders, doing the task vs. just resting in the scanner activated various visual and motor-related areas - no surprise. Playing the game vs. doing the control task in which there was no success or failure produced more activation in a handful of areas but only "at a more liberal threshold" i.e. this activation was not statistically reliable. A region-of-interest analysis found activation in the left nucleus accumbens and right orbitofrontal cortex, which are "reward-related" areas. In males, the game-specific activation was greater than in females in the right nucleus accumbens, the orbitofrontal cortex, and the right amygdala.

These areas are indeed "neural circuitries involved in reward and addiction" as the authors put it, but they're also activated whenever you experience anything pleasant or enjoyable, such as drinking water when you're thirsty. Water is not known to be addictive. So whether this study is relevant to video-game "addiction" is anyone's guess. As far as I can tell, all it shows is that men are more interested in simple, repetitive, abstract video games. But that's hardly news: in 2007 there was an International Pac-Man Championship with 30,000 entrants; the top 10 competitors were all male. (If anything in that last sentence surprises you, you haven't spent enough time on the internet.)

Anyway, that's the study. This is what the Telegraph made of it:

Playing on computer consoles activates parts of the male brain which are linked to rewarding feelings and addiction, scans have shown. The more opponents they vanquish and points they score, the more stimulated this region becomes. In contrast, these parts of women's brains are much less likely to be triggered by sessions on the Sony PlayStation, Nintendo Wii or Xbox.

Well, not quite. No opponents were vanquished and no Wii's were played. But so far this is just another fMRI study that attracted the attention of a journalist who knew how to spin a good story. Readers of Neuroskeptic will know this is not uncommon. However, it doesn't end there. Here's the really instructive bit:

Professor Allan Reiss of the Centre for Interdisciplinary Brain Sciences Research at Stanford University, California, who led the research, said that women understood computer games just as well as men but did not have the same neurological drive to win.
"These gender differences may help explain why males are more attracted to, and more likely to become 'hooked' on video games than females," he said.
"I think it's fair to say that males tend to be more intrinsically territorial. It doesn't take a genius to figure out who historically are the conquerors and tyrants of our species – they're the males.
"Most of the computer games that are really popular with males are territory and aggression-type games."

Now this is a theory - men like video games because we're intrinsically drawn to competition, conquest and territory-grabbing. This may or may not be true; personally, in the light of what I know of history and anthropology, I suspect it is, but even if you disagree, you can see that this is an important theory: it makes a big difference whether it's true or not.

However, the fMRI results have nothing to do with this theory. They neither support nor refute it, and nor could they; this experiment is essentially irrelevant to the theory in question. Prof. Allan Reiss is simply stating his personal opinions about human nature - however intelligent & informed these opinions may be. (Just to be clear, it's quite possible that Reiss didn't expect to be quoted in the way he was; he may have, not unreasonably, thought that he was just giving his informal opinion.) The Telegraph's sub-headline?

Men's passion for computer games stems from a deep-rooted urge to conquer, according to research

There are some lessons here.

1. If you want to know about something, study it.

If you want to learn about human behaviour, study human behaviour. Stanley Milgram discovered important things about behaviour; if he had never even heard about the brain, it wouldn't have stopped him from doing that.

Neuroscience can tell us about how behaviour happens. We get thirsty when we haven't drunk water for a while. Neuroscience, and only neuroscience, will tell you how. Some people get depressed or manic. One day, I hope, neuroscience will tell us the complete story of how - maybe mania will turn out to be caused by hyper-stimulation of a certain dopamine receptor - and we'll be able to stop it happening with some pill with a 100% success rate.

However, neuroscience can't tell you what human behaviour is: it cannot describe behaviour, it can only explain it. People know about thirst and depression and mania long before they knew anything about the brain. More importantly, and more subtly, neuroscience can only explain behaviour in the "how" sense; only rarely can it tell you why behaviour is the way that it is.

If someone is behaving in a certain way because of brain damage or disease, that's one of these rare cases. In that case "damage to area X caused by disease Y" is "why". But in most cases, it's not. To say that men like video games because their reward systems are more sensitive to video games is not a "why" explanation. It's a "how" explanation, and it leaves completely open the question of why the male brain is more sensitive to video games. The answer might be "innate biological differences due to evolution", or it might be "sexist upbringing", or "paternalistic culture", or anything else.

(This is often overlooked in discussions about psychiatry. Some people object to the idea that clinical depression is a neuro-chemical state, pointing out that depression can be caused by stress, rejection and other events in life. This is confused; there is no reason why stress or rejection could not cause a state of low serotonin. By extension, saying that someone has "low serotonin" always leaves open the question of why.)

2. Brains are people too

This leads on to a more subtle point. Some people understand the difference between how and why explanations, but feel that if the "how" is something to do with the brain, the "why" must be to do with the brain too. They look at brain scans showing that people behave in a certain way because their brain is a certain way (e.g. men like games because their reward system is more activated by games), and they think that there must be a "biological" explanation for why this is.

There might be, but there might not be. Brains are alive; they see and hear; they think; they talk; they feel. Your brain does everything you do, because you are "your" brain. The astonishing thing about brains is that they are both material, biological objects, and concious, living people, at the same time.

Your brain is not your liver, which is only affected by chemical and biological influences, like hormones, toxins, and bacteria. Your liver doesn't care whether you're a Christian or a Muslim, it cares about whether you drink alcohol. Your brain does care about your religion because some pattern of connections in your brain gives you the religion that you have.

Brain scans, by confronting us with the biological, material nature of the brain, make us look for biological, material why explanations. We forget that the brain might be the way it is because of cultural or historical or psychological or sociological or economic factors, because we forget that brains are people. We tend to think of people as being something beyond and above their brains. Ironically, it's this primitive dualism that leads to the most crude materialistic explanations for human behaviour.

3. Beware neuro-fetishists

There's a doctoral thesis in "Science Studies" to be written about how it came to happen, but that we fetishize the brain is obvious. For much of the 20th century, psychology was seen in the same way. Freud joined Nietschze, Marx and Heidegger in the ranks of Germanic names that literary theorists and lefty intellectuals loved to drop.

Then the bottom fell out of psychoanalysis, Prozac and fMRI arrived and the Decade of the Brain was upon us. Today, neuroscience is the new psychology - or perhaps psychology is becoming a branch of neuroscience. (If I asked you to depict psychology visually, you'd probably draw a brain - if you do a Google image search for "psychology", 10 out of the 21 front page hits depict either a brain or a head; this might not surprise you but it would have seemed odd 50 years ago.) There's a presumption that neuroscience is key to answering both how and why questions about the mind.

Neuroscience is now hot, but what people are mostly interested in are psychological and philosophical questions. People care about The Big Questions like -

"Is there life after death? Do we have free will? Is human nature fixed? Are men smarter/more aggressive/more promiscuous/better drivers than women? Why do people become criminals/geniuses/mad?"

These are good questions - but neuroscience has little to say about them, because they're not questions about the brain. They're questions for philosophers, or geneticists, or psychologists. No brain scan is going to tell you whether men are better drivers than women. It might tell you something about the processes by which make decisions while driving, but only a neuroscientist is likely to find that interesting.

P.S It turns out that people were saying similar things about this research back in Feburary. A blogger who writes about research on video games (neat) wrote about it way back then. So why did the Telegraph decide to resurrect the story as if it were new? That's just another one of life's mysteries.

[BPSDB]

(*) Which is so awesome.

F HOEFT, C WATSON, S KESLER, K BETTINGER, A REISS (2008). Gender differences in the mesocorticolimbic system during computer game-play Journal of Psychiatric Research, 42 (4), 253-258 DOI: 10.1016/j.jpsychires.2007.11.010

Links You Might Like

From the British Medical Journal, a man describes his wife's experience with depression and its succesful treatment with ECT. ("To me as a carer, it feels as if some malign, intangible entity has attached itself to my wife, constantly attacking her. Ana and I are very close: I can feel her mood as soon as I enter the same room as her, and when things are bad, the depression is like an oppressive weight that lies on us both. It sucks the colour out of life. I’ve never seen mentioned in any medical text just how truly terrifying depression is. It’s very, very scary, watching the one you love withdraw from life and turn into an inert stranger—and you can never, ever, relax, because you know that the spectre of suicide is always hanging over all your lives.")

Are Humans Hard-Wired to Ignore the Threat of Climate Change? - Excellent article from a few months back discussing research on risk perception and how it might be applied to make people take global warming seriously - basically, you need to scare people and then tell them how to solve the problem. Politicians have known that for a long time before psychologists said it, of course, but some of the research is interesting.

"If I look at the mass I will never act" - Psychologist Paul Slovic on the psychology of famine and genocide. Apparantly, people will donate more money to feed one child than they will to feed two children. Stalin knew that one death is a tragedy, a million deaths is a statistic - now we know that even two deaths is a statistic.

If you liked those last two, Greater Good Magazine has lots more of that kind of thing. It's from Berkeley and it's got a bit of a "positive psychology" vibe, but it's full of good stuff.

Finally, if you need cheering up, here's Chris Rock on a promising new antidepressant...

Links You Might Like

From the British Medical Journal, a man describes his wife's experience with depression and its succesful treatment with ECT. ("To me as a carer, it feels as if some malign, intangible entity has attached itself to my wife, constantly attacking her. Ana and I are very close: I can feel her mood as soon as I enter the same room as her, and when things are bad, the depression is like an oppressive weight that lies on us both. It sucks the colour out of life. I’ve never seen mentioned in any medical text just how truly terrifying depression is. It’s very, very scary, watching the one you love withdraw from life and turn into an inert stranger—and you can never, ever, relax, because you know that the spectre of suicide is always hanging over all your lives.")

Are Humans Hard-Wired to Ignore the Threat of Climate Change? - Excellent article from a few months back discussing research on risk perception and how it might be applied to make people take global warming seriously - basically, you need to scare people and then tell them how to solve the problem. Politicians have known that for a long time before psychologists said it, of course, but some of the research is interesting.

"If I look at the mass I will never act" - Psychologist Paul Slovic on the psychology of famine and genocide. Apparantly, people will donate more money to feed one child than they will to feed two children. Stalin knew that one death is a tragedy, a million deaths is a statistic - now we know that even two deaths is a statistic.

If you liked those last two, Greater Good Magazine has lots more of that kind of thing. It's from Berkeley and it's got a bit of a "positive psychology" vibe, but it's full of good stuff.

Finally, if you need cheering up, here's Chris Rock on a promising new antidepressant...

Are Faces Special?

There's been a glut of face-based science lately. There was the first American face transplant (the second if you count the ill-fated Travolta/Cage one...) Then an Atlanta group allegedly found that chimpanzees have a part of the brain specialized for recognizing the faces of their fellow chimps.

As I'll explain, this would be extremely important if true. This research is just the latest chapter in a long and contentious debate going back many years - a debate which, believe it or not, may hold the answer to Life, the Universe, and Everything! I'll get onto that later.

The human brain may, or may not, have regions which are "hard-wired" specifically for the visual processing of faces; the question of whether it does is generally known as the "Are Faces Special?" debate.(*) The majority of neuroscientists today would say that yes, they are, and that yes, we do have at least one such face area. I agree with this, but the debate's not yet ever - although as usual the reporting on this study glosses over such complexities.

On the face of it (ha), the evidence for specialized processing of faces in the human brain is very strong. We're very good at distinguishing and recognizing faces, despite the fact that they are all extremely similar - and when faces are shown upside-down, we are much worse at dealing with them. This suggests, to most people, that we have a specialized capacity for processing faces.

Following certain brain lesions, some patients lose their ability to recognize faces, a condition known as prosopagnosia. This most commonly follows damage to a part of the temporal lobe of the brain called the fusiform gyrus. Prosopagnosics may be able to identify and recognize other kinds of objects, but they just can't "get" faces. (Prosopagnosia can also be congenital i.e. present from birth). To a prosopagnosic, every face is as inscrutable as upside-down faces are to the rest of us.

Meanwhile, neuroimaging has consistently shown a small portion of the aforementioned fusiform gyrus on the right side, dubbed the "fusiform face area (FFA)", is more activated when people are looking at pictures of faces than when they are looking at inanimate objects, other body parts, or pictures of faces which have been scrambled up so as to no longer look like faces.

So all of the evidence seems to mesh together ("converge") splendidly: there's a face area in the human brain, located in the Fusiform Face Area, which is responsible for our unusually good face-processing abilities. Hurrah. However, there's a parade-raining alternative view, namely that faces are not special, we are only good at processing them because we have so much experience doing so, and the FFA's role lies in detecting the differences between similar objects about which we have learned to be highly familiar - faces being just one example.

The details of this debate are fairly bewildering. For what it's worth, the "expertise" account has always seemed rather contrived to me and expertise theorists seem to be on the defensive against the more confident and plausible "specialist" neuroscientists. But that's just my opinion. For an excellent overview of the neuroscience of faces see here; for a skeptical view of the Fusiform Face Area see this; for skepticism of the skepticism here.

Anyway, into this debate stepped Lisa Parr et. al. who used ¹⁸F-flurodeoxyglucose PET imaging to measure neural activity in five adult chimpanzees. Their goal was to see whether chimps possess a Fusiform Face Area or not. Chimps, unlike "lower" monkeys, are good at recognizing chimp (and human) faces. The five luckless chimps had to perform two tasks, one of which involved visually "matching" pictures of chimp faces in order to earn Kool-Aid. The other control task involved the same procedure but with matching non-face pictures ("Clip Art").

Subjects have been trained to control the movements of a cursor on the computer screen by manipulating the joystick ... At the beginning of a trial, a single image (the sample) appears on the computer screen on a black background. ... After this, the sample clears the screen and two comparison images appear on the monitor ... One of these comparisons matches the sample (the target), and the other (the foil) is a different image from the same category, either another face or another clip art object. ... Subjects must contact the image that matches the sample by contacting it with the joystick-controlled cursor.

Compared to the control Clip Art task, the chimp's brains were more active during the face task in a wide range of areas. The most "face-selective" area was the "Dorsal primary motor/medial parietal cortex (Left)" which has nothing to do with faces, vision, or any of that kind of stuff. The authors try to put a brave face on this (emphasis mine)...

The first [whole brain] analysis revealed numerous brain regions that showed greater metabolic activity during the face-matching task when compared directly to the object-matching ... [including] the posterior superior temporal sulcus (STS) and orbitofrontal cortex ... These regions comprise part of the distributed cortical network for face processing in humans. Notably absent from this analysis was activity in the fusiform gyrus, the primary region where face-selective activity is found in humans when the comparable analysis is used.

...but this is clearly a disappointing result. No chimp FFA found. Yet this is hardly surprising, considering that there were only five subjects in this experiment, and there's obviously a big difference between a human volunteer, and a chimpanzee who's spent years being experimented on, is locked in a cage, is highly trained on the computerized task, and who is doing the experiment for Kool-Aid.(**) The absence of evidence in this experiment is not evidence of absence.

All was not lost, however, because the authors then did a different analysis, looking for individual voxels (small parts of the brain) which were "face selective" or "object selective". (I suspect this was a post-hoc analysis, a naughty practice which I have warned about before, but here it's arguably OK). Short story - they found a lot of such voxels, most of them in areas which are nothing to do with faces or vision, but there were quite a few in the fusiform gyrus, which is where you might expect them to be based on human work (see above.) But honestly, neuroimaging data is noisy enough at the best of times and with just five subjects it's virtually impossible to draw any conclusions. A human PET study with n=5 would never get published; by the standards of chimp research n=5 is big because chimps are much harder to work with. Personally, I'm just glad I don't work with chimps.

What about Life, the Universe, and Everything? Well, the "Are Faces Special" debate is relevant to such cosmic questions (almost), because it's one aspect of the great "modularity" debate, which is basically psychologists and neuroscientists debating the existence of human nature. If humans are genetically programmed to have a part of the brain (a "module") specialized for processing faces, presumably this is because we evolved to do so. If so, then this makes it very plausible that other parts of our brains evolved for such specialist purposes, and this implies that our minds work in certain ways because of evolution (i.e Evolutionary Psychology) and that human nature is largely fixed.

On the other hand, if faces aren't special, maybe nothing is - maybe there is no such thing as human nature and all our behavior is learned by experience. That would imply that culture and history are much more important than biology in understanding human life, and that with sufficient political and social advancement anything is possible! Wow. That's the importance of neuroscience. At least, that's what neuroscientists will tell you when they want you to give them money or buy their books...

(*) If you're at a cognitive neuroscience conference and feel like a slap in the face, try opening a conversation with a pretty young grad student with the line "I don't know if faces are special, babe, but yours is".
(**) Although given the state of some undergrads, the differences might not always be in the human's favor.

L PARR, E HECHT, S BARKS, T PREUSS, J VOTAW (2008). Face Processing in the Chimpanzee Brain Current Biology DOI: 10.1016/j.cub.2008.11.048

Are Faces Special?

There's been a glut of face-based science lately. There was the first American face transplant (the second if you count the ill-fated Travolta/Cage one...) Then an Atlanta group allegedly found that chimpanzees have a part of the brain specialized for recognizing the faces of their fellow chimps.

As I'll explain, this would be extremely important if true. This research is just the latest chapter in a long and contentious debate going back many years - a debate which, believe it or not, may hold the answer to Life, the Universe, and Everything! I'll get onto that later.

The human brain may, or may not, have regions which are "hard-wired" specifically for the visual processing of faces; the question of whether it does is generally known as the "Are Faces Special?" debate.(*) The majority of neuroscientists today would say that yes, they are, and that yes, we do have at least one such face area. I agree with this, but the debate's not yet ever - although as usual the reporting on this study glosses over such complexities.

On the face of it (ha), the evidence for specialized processing of faces in the human brain is very strong. We're very good at distinguishing and recognizing faces, despite the fact that they are all extremely similar - and when faces are shown upside-down, we are much worse at dealing with them. This suggests, to most people, that we have a specialized capacity for processing faces.

Following certain brain lesions, some patients lose their ability to recognize faces, a condition known as prosopagnosia. This most commonly follows damage to a part of the temporal lobe of the brain called the fusiform gyrus. Prosopagnosics may be able to identify and recognize other kinds of objects, but they just can't "get" faces. (Prosopagnosia can also be congenital i.e. present from birth). To a prosopagnosic, every face is as inscrutable as upside-down faces are to the rest of us.

Meanwhile, neuroimaging has consistently shown a small portion of the aforementioned fusiform gyrus on the right side, dubbed the "fusiform face area (FFA)", is more activated when people are looking at pictures of faces than when they are looking at inanimate objects, other body parts, or pictures of faces which have been scrambled up so as to no longer look like faces.

So all of the evidence seems to mesh together ("converge") splendidly: there's a face area in the human brain, located in the Fusiform Face Area, which is responsible for our unusually good face-processing abilities. Hurrah. However, there's a parade-raining alternative view, namely that faces are not special, we are only good at processing them because we have so much experience doing so, and the FFA's role lies in detecting the differences between similar objects about which we have learned to be highly familiar - faces being just one example.

The details of this debate are fairly bewildering. For what it's worth, the "expertise" account has always seemed rather contrived to me and expertise theorists seem to be on the defensive against the more confident and plausible "specialist" neuroscientists. But that's just my opinion. For an excellent overview of the neuroscience of faces see here; for a skeptical view of the Fusiform Face Area see this; for skepticism of the skepticism here.

Anyway, into this debate stepped Lisa Parr et. al. who used ¹⁸F-flurodeoxyglucose PET imaging to measure neural activity in five adult chimpanzees. Their goal was to see whether chimps possess a Fusiform Face Area or not. Chimps, unlike "lower" monkeys, are good at recognizing chimp (and human) faces. The five luckless chimps had to perform two tasks, one of which involved visually "matching" pictures of chimp faces in order to earn Kool-Aid. The other control task involved the same procedure but with matching non-face pictures ("Clip Art").

Subjects have been trained to control the movements of a cursor on the computer screen by manipulating the joystick ... At the beginning of a trial, a single image (the sample) appears on the computer screen on a black background. ... After this, the sample clears the screen and two comparison images appear on the monitor ... One of these comparisons matches the sample (the target), and the other (the foil) is a different image from the same category, either another face or another clip art object. ... Subjects must contact the image that matches the sample by contacting it with the joystick-controlled cursor.

Compared to the control Clip Art task, the chimp's brains were more active during the face task in a wide range of areas. The most "face-selective" area was the "Dorsal primary motor/medial parietal cortex (Left)" which has nothing to do with faces, vision, or any of that kind of stuff. The authors try to put a brave face on this (emphasis mine)...

The first [whole brain] analysis revealed numerous brain regions that showed greater metabolic activity during the face-matching task when compared directly to the object-matching ... [including] the posterior superior temporal sulcus (STS) and orbitofrontal cortex ... These regions comprise part of the distributed cortical network for face processing in humans. Notably absent from this analysis was activity in the fusiform gyrus, the primary region where face-selective activity is found in humans when the comparable analysis is used.

...but this is clearly a disappointing result. No chimp FFA found. Yet this is hardly surprising, considering that there were only five subjects in this experiment, and there's obviously a big difference between a human volunteer, and a chimpanzee who's spent years being experimented on, is locked in a cage, is highly trained on the computerized task, and who is doing the experiment for Kool-Aid.(**) The absence of evidence in this experiment is not evidence of absence.

All was not lost, however, because the authors then did a different analysis, looking for individual voxels (small parts of the brain) which were "face selective" or "object selective". (I suspect this was a post-hoc analysis, a naughty practice which I have warned about before, but here it's arguably OK). Short story - they found a lot of such voxels, most of them in areas which are nothing to do with faces or vision, but there were quite a few in the fusiform gyrus, which is where you might expect them to be based on human work (see above.) But honestly, neuroimaging data is noisy enough at the best of times and with just five subjects it's virtually impossible to draw any conclusions. A human PET study with n=5 would never get published; by the standards of chimp research n=5 is big because chimps are much harder to work with. Personally, I'm just glad I don't work with chimps.

What about Life, the Universe, and Everything? Well, the "Are Faces Special" debate is relevant to such cosmic questions (almost), because it's one aspect of the great "modularity" debate, which is basically psychologists and neuroscientists debating the existence of human nature. If humans are genetically programmed to have a part of the brain (a "module") specialized for processing faces, presumably this is because we evolved to do so. If so, then this makes it very plausible that other parts of our brains evolved for such specialist purposes, and this implies that our minds work in certain ways because of evolution (i.e Evolutionary Psychology) and that human nature is largely fixed.

On the other hand, if faces aren't special, maybe nothing is - maybe there is no such thing as human nature and all our behavior is learned by experience. That would imply that culture and history are much more important than biology in understanding human life, and that with sufficient political and social advancement anything is possible! Wow. That's the importance of neuroscience. At least, that's what neuroscientists will tell you when they want you to give them money or buy their books...

(*) If you're at a cognitive neuroscience conference and feel like a slap in the face, try opening a conversation with a pretty young grad student with the line "I don't know if faces are special, babe, but yours is".
(**) Although given the state of some undergrads, the differences might not always be in the human's favor.

L PARR, E HECHT, S BARKS, T PREUSS, J VOTAW (2008). Face Processing in the Chimpanzee Brain Current Biology DOI: 10.1016/j.cub.2008.11.048

Serotonin! What Is It Good For?

Absolutely nothing...? Not quite, but it may be good for a lot less than anyone thought. At least according to a recent paper in PLoS One describing what happens to mice given genetic knockout which left them almost completely unable to produce the neurotransmitter serotonin (5HT).

The mice lacked either one, or both, of two genes called TPH1 and TPH2, which code for two related enzymes called tryptophan hydroxylase-1 and tryptophan hydroxylase-2. These are necessary for the production of serotonin from the amino acid tryptophan (which you get from eating turkey... and also most other foods). No tryptophan hydroxylase, no serotonin.

Tryptophan hydroxylase-1 is mostly responsible for making serotonin outside the brain, while tryptophan hydroxylase-2 predominates in neurones. So the mice lacking both enzymes ("double knockouts") should have had no serotonin at all, anywhere. In fact, chemical analysis revealed a small amount present in the brains, but it was >99% less than normal, and even this may have been some kind of contaminant rather than serotonin:

Reduction of 5-HT in TPH2KO mice ranged from 67.5% (cerebellum) to 96.9% (striatum), while 5-HT reduction in DKO mice ["double knockouts" who lacked both TPH1 and TPH2] ranged from 94.4% (cerebellum) to 99.2% (cortex). 5-HT levels were lower in DKO mice than in TPH2KO mice in all brain regions examined. The percentage of 5-HIAA reduction paralleled changes in 5-HT. No generalized changes were noted in other neurotransmitter levels.

So, what happened to these serotonin-less animals? The big story is - remarkably little. They were alive, for one thing. They weren't writhing in pain thinking "Every moment I live is agony!" like that mutant on The Simpsons. The double knockout mice were slightly smaller and leaner than usual (less body fat), but only by a few % points. Otherwise, they were normal on almost every measure. This is very surprising, given that serotonin is one of the oldest neurotransmitters in evolutionary terms. Even insects use serotonin as a transmitter. Even some single-celled organisms have serotonin. There are at least 14 different types of serotonin receptor in the mouse body (same for humans). What are they all doing? Nothing especially important, clearly.

The results dramatically indicate that 5-HT is not essential for overall development and that its role in behavior is modulatory rather than essential. Initial phenotypic analysis of these mutants revealed no differences in a range of measures of physical health including assays for cardiac, immune system, endocrine, and ophthalmic function (unpublished observations).

However, that's not the end of the story. The mice were also tested in a battery of standard behavioural tests used to measure anxiety levels and such like; these are commonly used to measure the effects of antidepressants and other such drugs in rodents. Given that antidepressants such as Prozac are supposed to work by increasing serotonin levels in the brain, you'd expect that mice with no serotonin would be "depressed".

The TPH1 knockout animals showed no differences at all - no surprise since, as you'll recall, they only lacked serotonin outside the brain e.g. in the intestines, where it seems to play a role in digestion - although presumably not a vital one. So, no surprise there. The TPH2 knockouts, and the TPH1/TPH2 double knockouts were remarkably normal too, showing no differences on most of the behavioural tests

For the TPH2KO and DKO, there were no differences between the KO or DKO and WT littermate control mice in motor coordination, acoustic startle response and sensorimotor gating, tonic inflammatory pain sensitivity, and learning and memory as assessed in inverted screen, pre-pulse inhibition, formalin paw, and trace fear conditioning assays, respectively

But they did show differences in the marble burying test, the forced swim test, and the tail suspension test. The double-knockouts generally showed the most profound effects. But here's the twist - far from being "depressed", the knockout mice were less "depressed" on the forced swim test (i.e. the genetic knockout had the same effect to that seen with antidepressants.) That is, they showed more struggling and less immobility. This is the exact opposite of what you might have expected.

On the other hand, the knockouts showed increased immobility on the tail suspension test, which is generally taken to be a depressive behaviour, and they buried more marbles in the marble burying test, which is opposite to the effects of Prozac. It's not clear what if anything burying more marbles means; some have suggested that the frantically burying mice are showing OCD-like symptoms. Hmm.

So, what these results show is that a) mice can live almost normal lives without serotonin, or at best with trace amounts, and b) the main effects of having no serotonin are upon "depression-like" behaviours, but whether the knockouts are more or less depressed is unclear (the authors push the idea that they're more depressed, but really it's impossible to say.) Still, this is a bit more evidence that the serotonin hypothesis of depression isn't quite dead.

To my mind, though, the most interesting result by far is that serotonin is so dispensible. Mice can live essentially normal lives without it, which is not true for most other neurotransmitters. Bear in mind, though, that just because serotonin is not necessary for normal functioning doesn't mean that if you do have serotonin, it isn't doing anything. It might be that in the knockout mice, other systems had taken over the roles normally played by serotonin.

Finally, this study was run by Lexicon Pharmaceuticals, who use genetic knockout technology to discover new drugs. They end by saying...

Our results strongly support targeting the 5-HT system to treat affective disorders and the use of knockout mice as a tool to tease apart mechanisms involved in the etiology of these disorders.

Take that as you will.

Katerina V. Savelieva, Shulei Zhao, Vladimir M. Pogorelov, Indrani Rajan, Qi Yang, Emily Cullinan, Thomas H. Lanthorn (2008). Genetic Disruption of Both Tryptophan Hydroxylase Genes Dramatically Reduces Serotonin and Affects Behavior in Models Sensitive to Antidepressants PLoS ONE, 3 (10) DOI: 10.1371/journal.pone.0003301