The Brain's Sarcasm Centre? Wow, That's Really Useful

A team of Japanese scientists have found the most sarcastic part of the brain known to date. They also found the metaphor centre of the brain and, well, it's kind of like a pair of glasses.

The paper is Distinction between the literal and intended meanings of sentences and it's brought to you by Uchiyama et al. They took 20 people and used fMRI to record neural activity while the volunteers read 4 kinds of statements:

• Literally true
• Nonsensical
• Sarcastic
• Metaphorical

The neat thing was that the statements themselves were the same in each case. The preceding context determined how they were to be interpreted. So for example, the statement "It was bone-breaking" was literally true when it formed part of a story about someone in hospital describing an accident; it was metaphorical in the context of someone describing how hard it was to do something difficult; and it was nonsensical if the context was completely unrelated ("He went to the bar and ordered:...").

Here's what they found. Compared to the literally-true and the nonsensical statements, which were a control condition, metaphorical statements activated the head of the caudate nucleus, the thalamus, and an area of the medial PFC they dub the "arMPFC" but which other people might call the pgACC or something even more exotic; names get a bit vague in the frontal lobe.


The caudate nucleus, as I said, looks like a pair of glasses. Except without the nose bit. The area activated by metaphors was the "lenses". Kind of.

Sarcasm however activated the same mPFC region, but not the caudate:

Sarcasm also activated the amygdala.

*

So what? This is a very nice fMRI study. 20 people is a lot, the task was well-designed and the overlap of the mPFC blobs in the sarcasm-vs-control and the metaphor-vs-control tasks was impressive. There's clearly something going on there in both cases, relative to just reading literal statements. Something's going on in the caudate and thalamus with metaphor but not sarcasm, too.

But what can this kind of study tell us about the brain? They've localized something-about-metaphor to the caudate nucleus, but what is it, and what does the caudate actually do to make that thing happen?

The authors offer a suggestion - the caudate is involved in "searching for the meaning" of the metaphorical statement in order to link it to the context, and work out what the metaphor is getting at. This isn't required for sarcasm because there's only one, literal, meaning - it's just reversed, the speaker actually thinks the exact opposite. Whereas with both sarcasm and metaphor you need to attribute intentions (mentalizing or "Theory of Mind").

That's as plausible an account as any but the problem is that we have no way of knowing, at least not from imaging studies, if it's true or not. As I said this is not the fault of this study but rather an inherent challenge for the whole enterprise. The problem is - switch on your caudate, metaphor coming up - a lot like the challenge facing biology in the aftermath of the Human Genome Project.

The HGP mapped the human genome, and like any map it told us where stuff is, in this case where genes are on chromosomes. You can browse it here. But by itself this didn't tell us anything about biology. We still have to work out what most of these genes actually do; and then we have to work out how they interact; and they we have to work out how those interactions interact with other genes and the environment...

Genomics people call this, broadly speaking, "annotating" the genome, although this is not perhaps an ideal term because it's not merely scribbling notes in the margins, it's the key to understanding. Without annotation, the genome's just a big list.

fMRI is building up a kind of human localization map, a blobome if you will, but by itself this doesn't really tell us much; other tools are required.

Uchiyama HT, Saito DN, Tanabe HC, Harada T, Seki A, Ohno K, Koeda T, & Sadato N (2011). Distinction between the literal and intended meanings of sentences: A functional magnetic resonance imaging study of metaphor and sarcasm. Cortex; a journal devoted to the study of the nervous system and behavior PMID: 21333979

The Brain's Sarcasm Centre? Wow, That's Really Useful

A team of Japanese scientists have found the most sarcastic part of the brain known to date. They also found the metaphor centre of the brain and, well, it's kind of like a pair of glasses.

The paper is Distinction between the literal and intended meanings of sentences and it's brought to you by Uchiyama et al. They took 20 people and used fMRI to record neural activity while the volunteers read 4 kinds of statements:

• Literally true
• Nonsensical
• Sarcastic
• Metaphorical

The neat thing was that the statements themselves were the same in each case. The preceding context determined how they were to be interpreted. So for example, the statement "It was bone-breaking" was literally true when it formed part of a story about someone in hospital describing an accident; it was metaphorical in the context of someone describing how hard it was to do something difficult; and it was nonsensical if the context was completely unrelated ("He went to the bar and ordered:...").

Here's what they found. Compared to the literally-true and the nonsensical statements, which were a control condition, metaphorical statements activated the head of the caudate nucleus, the thalamus, and an area of the medial PFC they dub the "arMPFC" but which other people might call the pgACC or something even more exotic; names get a bit vague in the frontal lobe.


The caudate nucleus, as I said, looks like a pair of glasses. Except without the nose bit. The area activated by metaphors was the "lenses". Kind of.

Sarcasm however activated the same mPFC region, but not the caudate:

Sarcasm also activated the amygdala.

*

So what? This is a very nice fMRI study. 20 people is a lot, the task was well-designed and the overlap of the mPFC blobs in the sarcasm-vs-control and the metaphor-vs-control tasks was impressive. There's clearly something going on there in both cases, relative to just reading literal statements. Something's going on in the caudate and thalamus with metaphor but not sarcasm, too.

But what can this kind of study tell us about the brain? They've localized something-about-metaphor to the caudate nucleus, but what is it, and what does the caudate actually do to make that thing happen?

The authors offer a suggestion - the caudate is involved in "searching for the meaning" of the metaphorical statement in order to link it to the context, and work out what the metaphor is getting at. This isn't required for sarcasm because there's only one, literal, meaning - it's just reversed, the speaker actually thinks the exact opposite. Whereas with both sarcasm and metaphor you need to attribute intentions (mentalizing or "Theory of Mind").

That's as plausible an account as any but the problem is that we have no way of knowing, at least not from imaging studies, if it's true or not. As I said this is not the fault of this study but rather an inherent challenge for the whole enterprise. The problem is - switch on your caudate, metaphor coming up - a lot like the challenge facing biology in the aftermath of the Human Genome Project.

The HGP mapped the human genome, and like any map it told us where stuff is, in this case where genes are on chromosomes. You can browse it here. But by itself this didn't tell us anything about biology. We still have to work out what most of these genes actually do; and then we have to work out how they interact; and they we have to work out how those interactions interact with other genes and the environment...

Genomics people call this, broadly speaking, "annotating" the genome, although this is not perhaps an ideal term because it's not merely scribbling notes in the margins, it's the key to understanding. Without annotation, the genome's just a big list.

fMRI is building up a kind of human localization map, a blobome if you will, but by itself this doesn't really tell us much; other tools are required.

Uchiyama HT, Saito DN, Tanabe HC, Harada T, Seki A, Ohno K, Koeda T, & Sadato N (2011). Distinction between the literal and intended meanings of sentences: A functional magnetic resonance imaging study of metaphor and sarcasm. Cortex; a journal devoted to the study of the nervous system and behavior PMID: 21333979

Premature Brain Diagnosis in Japan?

Nature has a disturbing article from their Asian correspondent David Cyranoski: Thought experiment. It's open access.

In brief: a number of top Japanese psychiatrists have started offering a neuroimaging method called NIRS to their patients as a diagnostic tool. They claim that NIRS shows the neural signatures of different mental illnesses.

The technology was approved by the Japanese authorities in April 2009, and since then it's been used on at least 300 patients, who pay $160 for the privilege. However, it's not clear that it works.

To put it mildly.

*

NIRS is Near Infra-Red Spectroscopy. It measures blood flow and oxygenation in the brain. In this respect, it's much like fMRI, but whereas fMRI uses superconducting magnets and quantum wizardry to achieve this, NIRS simply shines a near-infra-red light into the head, and records the light reflected back

It's a lot cheaper and easier than MRI. However, the images it provides are a lot less detailed, and it can only image the surface of the brain. NIRS has a small but growing number of users in neuroscience research; it's especially popular in Japan, for some reason, but it's also found plenty of users elsewhere.

The clinical use of NIRS in psychiatry was pioneered by one Dr Masato Fukuda, and he's been responsible for most of the trials. So what are these trials?

As far as I can see (correct me if I'm wrong), these are all the trials comparing patients and controls that he's been an author on:

• Matsuo et al (2000) n=9/10 elderly depressed/controls
• Suto et al (2004) n=10/13/16 depressed/schizophrenia/controls
• Kameyama et al (2006) n=17/11/17 bipolar/depression/controls
• Nishimura et al (2007) n=5/33 panic disorder/controls
• Takizawa et al (2008) n=55/70 schizophrenia/controls
• Uehara et al (2007) n=11/11 eating disorder/controls
• Suda et al (2010) n=27/27 eating disorder/controls

There are also a handful of Fukuda's papers in Japanese, which I can't read, but as far as I can tell they're general discussions rather than data papers.

So we have 342 people in all. Actually, a bit less, because some of them were included in more than one study. That's still quite a lot - but there were only 5 panic patients, 30 depressed (including 9 elderly, who may be different), 38 eating disordered and just 17 bipolar in the mix.

And the bipolar people were currently feeling fine, or just a little bit down, at the time of the NIRS. There are quite a lot of other trials from other Japanese groups, but sticking with bipolar disorder as an example, no trials that I could find examined people who were currently ill. The only other two trials, both very small, were in recovered people (1,2).

Given that the whole point of diagnosis is to find out what any given patient has, when they're ill, this matters to every patient. Anyone could be psychotic, or depressed, or eating disordered, or any combination thereof.

Worse yet, in many of these studies the patients were taking medications. In the 2006 depression/bipolar paper, for example, all of the bipolars were on heavy-duty mood stabilizers, mostly lithium; plus a few antipsychotics, and lots of antidepressants. The depressed people were on antidepressants.

There's a deeper problem. Fukuda says that NIRS corresponds with the clinical diagnosis in 80% of cases. Let's assume that's true. Well, if the NIRS agrees with the clinical diagnosis, it doesn't tell us anything we didn't already know. If the NIRS disagrees, who do you trust?

I think you'd have to trust the clinician, because the clinician is the "gold standard" against which the NIRS is compared. Psychiatric diseases are defined clinically. If you had to choose between 80% gold and pure gold, it's not a hard choice.

Now NIRS could, in theory, be better than clinical diagnosis: it could provide more accurate prognosis, and more useful treatment recommendations. That would be cool. But as far as I can see there's absolutely no published evidence on that.

To find out you'd have to compare patients diagnosed with NIRS to patients diagnosed normally - or better, to those randomized to get fake placebo NIRS, like the authors of this trial from last year should have done. To my knowledge, there have been no such tests at all.

*

So what? NIRS is harmless, quick, and $160 is not a lot. Patients like it: “They want some kind of hard evidence,” [Fukuda says], especially when they have to explain absences from work. If it helps people to come to terms with their illness - no mean feat in many cases - what's the problem?

My worry is that it could mean misdiagnosing patients, and therefore mis-treating them. Here's the most disturbing bit of the article:

...when Fukuda calculates his success rates, NIRS results that match the clinical diagnosis are considered a success. If the results don’t match, Fukuda says he will ask the patient and patient’s family “repeatedly” whether they might have missed something — for example, whether a depressed patient whose NIRS examination suggests schizophrenia might have forgotten to mention that he was experiencing hallucinations.

Quite apart from the implication that the 80% success rate might be inflated, this suggests that some dubious clinical decisions might be going on. The first-line treatments for schizophrenia are quite different, and rather less pleasant, than those for depression. A lot of perfectly healthy people report "hallucinations" if you probe hard enough. "Seek, and ye shall find". So be careful what you seek for.

While NIRS is a Japanese speciality, other brain-based diagnostic or "treatment personalization" tools are being tested elsewhere. In the USA, EEG has been proposed by a number of groups. I've been rather critical of these methods, but at least they've done some trials to establish whether this actually improves patient outcomes.

In my view, all of these "diagnostic" or "predictive" tools should be subject to exactly the same tests as treatments are: double blind, randomized, sham-controlled trials.

Cyranoski, D. (2011). Neuroscience: Thought experiment Nature, 469 (7329), 148-149 DOI: 10.1038/469148a

Premature Brain Diagnosis in Japan?

Nature has a disturbing article from their Asian correspondent David Cyranoski: Thought experiment. It's open access.

In brief: a number of top Japanese psychiatrists have started offering a neuroimaging method called NIRS to their patients as a diagnostic tool. They claim that NIRS shows the neural signatures of different mental illnesses.

The technology was approved by the Japanese authorities in April 2009, and since then it's been used on at least 300 patients, who pay $160 for the privilege. However, it's not clear that it works.

To put it mildly.

*

NIRS is Near Infra-Red Spectroscopy. It measures blood flow and oxygenation in the brain. In this respect, it's much like fMRI, but whereas fMRI uses superconducting magnets and quantum wizardry to achieve this, NIRS simply shines a near-infra-red light into the head, and records the light reflected back

It's a lot cheaper and easier than MRI. However, the images it provides are a lot less detailed, and it can only image the surface of the brain. NIRS has a small but growing number of users in neuroscience research; it's especially popular in Japan, for some reason, but it's also found plenty of users elsewhere.

The clinical use of NIRS in psychiatry was pioneered by one Dr Masato Fukuda, and he's been responsible for most of the trials. So what are these trials?

As far as I can see (correct me if I'm wrong), these are all the trials comparing patients and controls that he's been an author on:

• Matsuo et al (2000) n=9/10 elderly depressed/controls
• Suto et al (2004) n=10/13/16 depressed/schizophrenia/controls
• Kameyama et al (2006) n=17/11/17 bipolar/depression/controls
• Nishimura et al (2007) n=5/33 panic disorder/controls
• Takizawa et al (2008) n=55/70 schizophrenia/controls
• Uehara et al (2007) n=11/11 eating disorder/controls
• Suda et al (2010) n=27/27 eating disorder/controls

There are also a handful of Fukuda's papers in Japanese, which I can't read, but as far as I can tell they're general discussions rather than data papers.

So we have 342 people in all. Actually, a bit less, because some of them were included in more than one study. That's still quite a lot - but there were only 5 panic patients, 30 depressed (including 9 elderly, who may be different), 38 eating disordered and just 17 bipolar in the mix.

And the bipolar people were currently feeling fine, or just a little bit down, at the time of the NIRS. There are quite a lot of other trials from other Japanese groups, but sticking with bipolar disorder as an example, no trials that I could find examined people who were currently ill. The only other two trials, both very small, were in recovered people (1,2).

Given that the whole point of diagnosis is to find out what any given patient has, when they're ill, this matters to every patient. Anyone could be psychotic, or depressed, or eating disordered, or any combination thereof.

Worse yet, in many of these studies the patients were taking medications. In the 2006 depression/bipolar paper, for example, all of the bipolars were on heavy-duty mood stabilizers, mostly lithium; plus a few antipsychotics, and lots of antidepressants. The depressed people were on antidepressants.

There's a deeper problem. Fukuda says that NIRS corresponds with the clinical diagnosis in 80% of cases. Let's assume that's true. Well, if the NIRS agrees with the clinical diagnosis, it doesn't tell us anything we didn't already know. If the NIRS disagrees, who do you trust?

I think you'd have to trust the clinician, because the clinician is the "gold standard" against which the NIRS is compared. Psychiatric diseases are defined clinically. If you had to choose between 80% gold and pure gold, it's not a hard choice.

Now NIRS could, in theory, be better than clinical diagnosis: it could provide more accurate prognosis, and more useful treatment recommendations. That would be cool. But as far as I can see there's absolutely no published evidence on that.

To find out you'd have to compare patients diagnosed with NIRS to patients diagnosed normally - or better, to those randomized to get fake placebo NIRS, like the authors of this trial from last year should have done. To my knowledge, there have been no such tests at all.

*

So what? NIRS is harmless, quick, and $160 is not a lot. Patients like it: “They want some kind of hard evidence,” [Fukuda says], especially when they have to explain absences from work. If it helps people to come to terms with their illness - no mean feat in many cases - what's the problem?

My worry is that it could mean misdiagnosing patients, and therefore mis-treating them. Here's the most disturbing bit of the article:

...when Fukuda calculates his success rates, NIRS results that match the clinical diagnosis are considered a success. If the results don’t match, Fukuda says he will ask the patient and patient’s family “repeatedly” whether they might have missed something — for example, whether a depressed patient whose NIRS examination suggests schizophrenia might have forgotten to mention that he was experiencing hallucinations.

Quite apart from the implication that the 80% success rate might be inflated, this suggests that some dubious clinical decisions might be going on. The first-line treatments for schizophrenia are quite different, and rather less pleasant, than those for depression. A lot of perfectly healthy people report "hallucinations" if you probe hard enough. "Seek, and ye shall find". So be careful what you seek for.

While NIRS is a Japanese speciality, other brain-based diagnostic or "treatment personalization" tools are being tested elsewhere. In the USA, EEG has been proposed by a number of groups. I've been rather critical of these methods, but at least they've done some trials to establish whether this actually improves patient outcomes.

In my view, all of these "diagnostic" or "predictive" tools should be subject to exactly the same tests as treatments are: double blind, randomized, sham-controlled trials.

Cyranoski, D. (2011). Neuroscience: Thought experiment Nature, 469 (7329), 148-149 DOI: 10.1038/469148a

Left Wing vs. Right Wing Brains

So apparently: Left wing or right wing? It's written in the brain

People with liberal views tended to have increased grey matter in the anterior cingulate cortex, a region of the brain linked to decision-making, in particular when conflicting information is being presented...

Conservatives, meanwhile, had increased grey matter in the amygdala, an area of the brain associated with processing emotion.

This was based on a study of 90 young adults using MRI to measure brain structure. Sadly that press release is all we know about the study at the moment, because it hasn't been published yet. The BBC also have no fewer than three radio shows about it here, here and here.

Politics blog Heresy Corner discusses it...

Subjects who professed liberal or left-wing opinions tended to have a larger anterior cingulate cortex, an area of the brain which, we were told, helps process complex and conflicting information. (Perhaps they need this extra grey matter to be able to cope with the internal contradictions of left-wing philosophy.)

This kind of story tends to attract chuckle-some comments.

In truth, without seeing the full scientific paper, we can't know whether the differences they found were really statistically solid, or whether they were voodoo or fishy. The authors, Geraint Rees and Ryota Kanai, have both published a lot of excellent neuroscience in the past, but that's no guarantee.

In fact, however, I suspect that the brain is just the wrong place to look if you're interested in politics, because most political views don't originate in the individual brain, they originate in the wider culture and are absorbed and regurgitated without much thought. This is a real shame, because all of us, left or right, have a brain, and it's really quite nifty:

But when it comes to politics we generally don't use it. The brain is a powerful organ designed to help you deal with reality in all its complexity. For a lot of people, politics doesn't take place there, it happens in fairytale kingdoms populated by evil monsters, foolish jesters, and brave knights.

Given that the characters in this story are mindless stereotypes, there's no need for empathy. Because the plot comes fully-formed from TV or a newspaper, there's no need for original ideas. Because everything is either obviously right or obviously wrong, there's not much reasoning required. And so on. Which is why this happens amongst other things.

I don't think individual personality is very important in determining which political narratives and values you adopt: your family background, job, and position in society is much more important.

Where individual differences matter, I think, is in deciding how "conservative" or "radical" you are within whatever party you find yourself. Not in the sense of left or right, but in terms of how keen you are on grand ideas and big changes, as opposed to cautious, boring pragmatism.

In this sense, there are conservative liberals (i.e. Obama) and radical conservatives (i.e. Palin), and that's the kind of thing I'd be looking for if I were trying to find political differences in the brain.

Links: If right wingers have bigger amygdalae, does that mean patient SM, the woman with no amygdalae at all, must be a communist? Then again, Neuroskeptic readers may remember that the brain itself is a communist...

Left Wing vs. Right Wing Brains

So apparently: Left wing or right wing? It's written in the brain

People with liberal views tended to have increased grey matter in the anterior cingulate cortex, a region of the brain linked to decision-making, in particular when conflicting information is being presented...

Conservatives, meanwhile, had increased grey matter in the amygdala, an area of the brain associated with processing emotion.

This was based on a study of 90 young adults using MRI to measure brain structure. Sadly that press release is all we know about the study at the moment, because it hasn't been published yet. The BBC also have no fewer than three radio shows about it here, here and here.

Politics blog Heresy Corner discusses it...

Subjects who professed liberal or left-wing opinions tended to have a larger anterior cingulate cortex, an area of the brain which, we were told, helps process complex and conflicting information. (Perhaps they need this extra grey matter to be able to cope with the internal contradictions of left-wing philosophy.)

This kind of story tends to attract chuckle-some comments.

In truth, without seeing the full scientific paper, we can't know whether the differences they found were really statistically solid, or whether they were voodoo or fishy. The authors, Geraint Rees and Ryota Kanai, have both published a lot of excellent neuroscience in the past, but that's no guarantee.

In fact, however, I suspect that the brain is just the wrong place to look if you're interested in politics, because most political views don't originate in the individual brain, they originate in the wider culture and are absorbed and regurgitated without much thought. This is a real shame, because all of us, left or right, have a brain, and it's really quite nifty:

But when it comes to politics we generally don't use it. The brain is a powerful organ designed to help you deal with reality in all its complexity. For a lot of people, politics doesn't take place there, it happens in fairytale kingdoms populated by evil monsters, foolish jesters, and brave knights.

Given that the characters in this story are mindless stereotypes, there's no need for empathy. Because the plot comes fully-formed from TV or a newspaper, there's no need for original ideas. Because everything is either obviously right or obviously wrong, there's not much reasoning required. And so on. Which is why this happens amongst other things.

I don't think individual personality is very important in determining which political narratives and values you adopt: your family background, job, and position in society is much more important.

Where individual differences matter, I think, is in deciding how "conservative" or "radical" you are within whatever party you find yourself. Not in the sense of left or right, but in terms of how keen you are on grand ideas and big changes, as opposed to cautious, boring pragmatism.

In this sense, there are conservative liberals (i.e. Obama) and radical conservatives (i.e. Palin), and that's the kind of thing I'd be looking for if I were trying to find political differences in the brain.

Links: If right wingers have bigger amygdalae, does that mean patient SM, the woman with no amygdalae at all, must be a communist? Then again, Neuroskeptic readers may remember that the brain itself is a communist...

Delusions of Gender

Note: This book quotes me approvingly, so this is not quite a disinterested review.

Cordelia Fine's Delusions of Gender is an engaging, entertaining and powerfully argued reply to the many authors - who range from the scientifically respectable to the less so - who've recently claimed to have shown biological sex differences in brain, mind and behaviour.

Fine makes a strong case that the sex differences we see, in everything from behaviour to school achievements in mathematics, could be caused by the society in which we live, rather than by biology. Modern culture, she says, while obviously less sexist than in the past, still contains deeply entrenched assumptions about how boys and girls ought to behave, what they ought to do and what they're good at, and these - consciously or unconsciously - shape the way we are.

Some of the Fine's targets are obviously bonkers, like Vicky Tuck, but for me, the most interesting chapters were those dealing in detail with experiments which have been held up as the strongest examples of sex differences, such as the Cambridge study claiming that newborn boys and girls differ in how much they prefer looking at faces as opposed to mechanical mobiles.

But Delusions is not, in Steven Pinker's phrase, saying we ought to return to "Blank Slatism", and it doesn't try to convince you that every single sex difference definately is purely cultural. It's more modest, and hence, much more believable: simply a reminder that the debate is still an open one.

Fine makes a convincing case (well, it convinced me) that the various scientific findings, mostly from the past 10 years, that seem to prove biological differences, are not, on the whole, very strong, and that even if we do accept their validity, they don't rule out a role for culture as well.

This latter point is, I think, especially important. Take, for example, the fact that in every country on record, men roughly between the ages of 16-30 are responsible for the vast majority of violent crimes. This surely reflects biology somehow; whether it's the fact that young men are physically the strongest people, or whether it's more psychological, is by the by.

But this doesn't mean that young men are always violent. In some countries, like Japan, violent crime is extremely rare; in other countries, it's tens of times more common; and during wars or other periods of disorder, it becomes the norm. Young men are always, relatively speaking, the most violent but the absolute rate of violence varies hugely, and that has nothing to do with gender. It's not that violent places have more men than peaceful ones.

Gender, in other words, doesn't explain violence in any useful way - even though there surely are gender differences. The same goes for everything else: men and women may well have, for biological reasons, certain tendencies or advantages, but that doesn't automatically explain (and it doesn't justify) all of the sex differences we see today; it's only ever a partial explanation, with culture being the other part.

Delusions of Gender

Note: This book quotes me approvingly, so this is not quite a disinterested review.

Cordelia Fine's Delusions of Gender is an engaging, entertaining and powerfully argued reply to the many authors - who range from the scientifically respectable to the less so - who've recently claimed to have shown biological sex differences in brain, mind and behaviour.

Fine makes a strong case that the sex differences we see, in everything from behaviour to school achievements in mathematics, could be caused by the society in which we live, rather than by biology. Modern culture, she says, while obviously less sexist than in the past, still contains deeply entrenched assumptions about how boys and girls ought to behave, what they ought to do and what they're good at, and these - consciously or unconsciously - shape the way we are.

Some of the Fine's targets are obviously bonkers, like Vicky Tuck, but for me, the most interesting chapters were those dealing in detail with experiments which have been held up as the strongest examples of sex differences, such as the Cambridge study claiming that newborn boys and girls differ in how much they prefer looking at faces as opposed to mechanical mobiles.

But Delusions is not, in Steven Pinker's phrase, saying we ought to return to "Blank Slatism", and it doesn't try to convince you that every single sex difference definately is purely cultural. It's more modest, and hence, much more believable: simply a reminder that the debate is still an open one.

Fine makes a convincing case (well, it convinced me) that the various scientific findings, mostly from the past 10 years, that seem to prove biological differences, are not, on the whole, very strong, and that even if we do accept their validity, they don't rule out a role for culture as well.

This latter point is, I think, especially important. Take, for example, the fact that in every country on record, men roughly between the ages of 16-30 are responsible for the vast majority of violent crimes. This surely reflects biology somehow; whether it's the fact that young men are physically the strongest people, or whether it's more psychological, is by the by.

But this doesn't mean that young men are always violent. In some countries, like Japan, violent crime is extremely rare; in other countries, it's tens of times more common; and during wars or other periods of disorder, it becomes the norm. Young men are always, relatively speaking, the most violent but the absolute rate of violence varies hugely, and that has nothing to do with gender. It's not that violent places have more men than peaceful ones.

Gender, in other words, doesn't explain violence in any useful way - even though there surely are gender differences. The same goes for everything else: men and women may well have, for biological reasons, certain tendencies or advantages, but that doesn't automatically explain (and it doesn't justify) all of the sex differences we see today; it's only ever a partial explanation, with culture being the other part.

Genes To Brains To Minds To... Murder?

A group of Italian psychiatrists claim to explain How Neuroscience and Behavioral Genetics Improve Psychiatric Assessment: Report on a Violent Murder Case.

The paper presents the horrific case of a 24 year old woman from Switzerland who smothered her newborn son to death immediately after giving birth in her boyfriend's apartment. After her arrest, she claimed to have no memory of the event. She had a history of multiple drug abuse, including heroin, from the age of 13.

Forensic psychiatrists were asked to assess her case and try to answer the question of whether "there was substantial evidence that the defendant had an irresistible impulse to commit the crime." The paper doesn't discuss the outcome of the trial, but the authors say that in their opinion she exhibits a pattern of "pathologically impulsivity, antisocial tendencies, lack of planning...causally linked to the crime, thus providing the basis for an insanity defense."

But that's not all. In the paper, the authors bring neuroscience and genetics into the case in an attempt to provide

a more “objective description” of the defendant’s mental disease by providing evidence that the disease has “hard” biological bases. This is particularly important given that psychiatric symptoms may be easily faked as they are mostly based on the defendant’s verbal report.

So they scanned her brain, and did DNA tests for 5 genes which have been previously linked to mental illness, impulsivity, or violent behaviour. What happened? Apparently her brain has "reduced gray matter volume in the left prefrontal cortex" - but that was compared to just 6 healthy control women. You really can't do this kind of analysis on a single subject, anyway.

As for her genes, well, she had genes. On the famous and much-debated 5HTTLPR polymorphism, for example, her genotype was long/short; while it's true that short is generally considered the "bad" genotype, something like 40% of white people, and an even higher proportion of East Asians, carry it. The situation was similar for the other four genes (STin2 (SCL6A4), rs4680 (COMT), MAOA-uVNTR, DRD4-2/11, for gene geeks).

I've previously posted about cases in which a well-defined disorder of the brain led to criminal behaviour. There was the man who became obsessed with child pornography following surgical removal of a tumour in his right temporal lobe. There are the people who show "sociopathic" behaviour following fronto-temporal degeneration.

However this woman's brain was basically "normal" at least as far as a basic MRI scan could determine. All the pieces were there. Her genotypes was also normal in that lots of normal people carry the same genes; it's not (as far as we know) that she has a rare genetic mutation like Brunner syndrome in which an important gene is entirely missing. So I don't think neurobiology has much to add to this sad story.

*

We're willing to excuse perpetrators when there's a straightforward "biological cause" for their criminal behaviour: it's not their fault, they're ill. In all other cases, we assign blame: biology is a valid excuse, but nothing else is.

There seems to be a basic difference between the way in which we think about "biological" as opposed to "environmental" causes of behaviour. This is related, I think, to the Seductive Allure of Neuroscience Explanations and our fascination with brain scans that "prove that something is in the brain". But when you start to think about it, it becomes less and less clear that this distinction works.

A person's family, social and economic background is the strongest known predictor of criminality. Guys from stable, affluent families rarely mug people; some men from poor, single-parent backgrounds do. But muggers don't choose to be born into that life any more than the child-porn addict chose to have brain cancer.

Indeed, the mugger's situation is a more direct cause of his behaviour than a brain tumour. It's not hard to see how a mugger becomes, specifically, a mugger: because they've grown up with role-models who do that; because their friends do it or at least condone it; because it's the easiest way for them to make money.

But it's less obvious how brain damage by itself could cause someone to seek child porn. There's no child porn nucleus in the brain. Presumably, what it does is to remove the person's capacity for self-control, so they can't stop themselves from doing it.

This fits with the fact that people who show criminal behaviour after brain lesions often start to eat and have (non-criminal) sex uncontrollably as well. But that raises the question of why they want to do it in the first place. Were they, in some sense, a pedophile all along? If so, can we blame them for that?

Rigoni D, Pellegrini S, Mariotti V, Cozza A, Mechelli A, Ferrara SD, Pietrini P, & Sartori G (2010). How neuroscience and behavioral genetics improve psychiatric assessment: report on a violent murder case. Frontiers in behavioral neuroscience, 4 PMID: 21031162

Genes To Brains To Minds To... Murder?

A group of Italian psychiatrists claim to explain How Neuroscience and Behavioral Genetics Improve Psychiatric Assessment: Report on a Violent Murder Case.

The paper presents the horrific case of a 24 year old woman from Switzerland who smothered her newborn son to death immediately after giving birth in her boyfriend's apartment. After her arrest, she claimed to have no memory of the event. She had a history of multiple drug abuse, including heroin, from the age of 13.

Forensic psychiatrists were asked to assess her case and try to answer the question of whether "there was substantial evidence that the defendant had an irresistible impulse to commit the crime." The paper doesn't discuss the outcome of the trial, but the authors say that in their opinion she exhibits a pattern of "pathologically impulsivity, antisocial tendencies, lack of planning...causally linked to the crime, thus providing the basis for an insanity defense."

But that's not all. In the paper, the authors bring neuroscience and genetics into the case in an attempt to provide

a more “objective description” of the defendant’s mental disease by providing evidence that the disease has “hard” biological bases. This is particularly important given that psychiatric symptoms may be easily faked as they are mostly based on the defendant’s verbal report.

So they scanned her brain, and did DNA tests for 5 genes which have been previously linked to mental illness, impulsivity, or violent behaviour. What happened? Apparently her brain has "reduced gray matter volume in the left prefrontal cortex" - but that was compared to just 6 healthy control women. You really can't do this kind of analysis on a single subject, anyway.

As for her genes, well, she had genes. On the famous and much-debated 5HTTLPR polymorphism, for example, her genotype was long/short; while it's true that short is generally considered the "bad" genotype, something like 40% of white people, and an even higher proportion of East Asians, carry it. The situation was similar for the other four genes (STin2 (SCL6A4), rs4680 (COMT), MAOA-uVNTR, DRD4-2/11, for gene geeks).

I've previously posted about cases in which a well-defined disorder of the brain led to criminal behaviour. There was the man who became obsessed with child pornography following surgical removal of a tumour in his right temporal lobe. There are the people who show "sociopathic" behaviour following fronto-temporal degeneration.

However this woman's brain was basically "normal" at least as far as a basic MRI scan could determine. All the pieces were there. Her genotypes was also normal in that lots of normal people carry the same genes; it's not (as far as we know) that she has a rare genetic mutation like Brunner syndrome in which an important gene is entirely missing. So I don't think neurobiology has much to add to this sad story.

*

We're willing to excuse perpetrators when there's a straightforward "biological cause" for their criminal behaviour: it's not their fault, they're ill. In all other cases, we assign blame: biology is a valid excuse, but nothing else is.

There seems to be a basic difference between the way in which we think about "biological" as opposed to "environmental" causes of behaviour. This is related, I think, to the Seductive Allure of Neuroscience Explanations and our fascination with brain scans that "prove that something is in the brain". But when you start to think about it, it becomes less and less clear that this distinction works.

A person's family, social and economic background is the strongest known predictor of criminality. Guys from stable, affluent families rarely mug people; some men from poor, single-parent backgrounds do. But muggers don't choose to be born into that life any more than the child-porn addict chose to have brain cancer.

Indeed, the mugger's situation is a more direct cause of his behaviour than a brain tumour. It's not hard to see how a mugger becomes, specifically, a mugger: because they've grown up with role-models who do that; because their friends do it or at least condone it; because it's the easiest way for them to make money.

But it's less obvious how brain damage by itself could cause someone to seek child porn. There's no child porn nucleus in the brain. Presumably, what it does is to remove the person's capacity for self-control, so they can't stop themselves from doing it.

This fits with the fact that people who show criminal behaviour after brain lesions often start to eat and have (non-criminal) sex uncontrollably as well. But that raises the question of why they want to do it in the first place. Were they, in some sense, a pedophile all along? If so, can we blame them for that?

Rigoni D, Pellegrini S, Mariotti V, Cozza A, Mechelli A, Ferrara SD, Pietrini P, & Sartori G (2010). How neuroscience and behavioral genetics improve psychiatric assessment: report on a violent murder case. Frontiers in behavioral neuroscience, 4 PMID: 21031162

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, happen.

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...

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, happen.

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...

You're (Brain Is) So Immature

How mature are you? Have you ever wanted to find out, with a 5 minute brain scan? Of course you have. And now you can, thanks to a new Science paper, Prediction of Individual Brain Maturity Using fMRI.

This is another clever application of the support vector machine (SVM) method, which I've written about previously, most recently regarding "the brain scan to diagnose autism". An SVM is a machine learning algorithm: give it a bunch of data, and it'll find patterns in it.

In this case, the input data was brain scans from children, teenagers and adults, and the corresponding ages of each brain. The pattern the SVM was asked to find was the relationship between age and some complex set of parameters about the brain.

The scan was resting state functional connectivity fMRI. This measures the degree to which different areas of the brain tend to activate or deactivate together while you're just lying there (hence "resting"). A high connectivity between two regions means that they're probably "talking to each other", although not necessarily directly.

It worked fairly well:

Out of 238 people aged 7 to 30, the SVM was able to "predict" age pretty nicely on the basis of the resting state scan. This graph shows chronological age against predicted brain age (or "fcMI" as they call it). The correlation is strong: r2=0.55.

The authors then tested it on two other large datasets: one was resting state, but conducted on a less powerful scanner (1.5T vs 3.0T) (n=195), and the other was not designed as a resting state scan at all, but did happen to include some resting state-like data (n=186). Despite the fact that these data were, therefore, very different to the original dataset, the SVM was able to predict age with r2 over 0.5 as well.

*

What use would this be? Well, good question. It would be all too easy to, say, find a scan of your colleague's brain, run it through the Mature-O-Meter, and announce with glee that they have a neurological age of 12, which explains a lot. For example.

However, while this would be funny, it wouldn't necessarily tell you anything about them. We already know everyone's neurological age. It's... their age. Your brain is an old as you are. These data raise the interesting possibility that people with a higher Maturity Index, for their age, are actually more "mature" people, whatever that means. But that might not be true at all. We'll have to wait and see.

How does this help us to understand the brain? An SVM is an incredibly powerful mathematical tool for detecting non-linear correlations in complex data. But just running an SVM on some data doesn't mean we've learned anything: only the SVM has. It's a machine learning algorithm, that's what it does. There's a risk that we'll get "science without understanding" as I've written a while back.

In fact the authors did make a start on this and the results were pretty neat. They found that as the brain matures, long-range functional connections within the brain become stronger, but short-range interactions between neighbours get weaker and this local disconnection with age is the most reliable change.

You can see this on the pic above: long connections get stronger (orange) while short ones get weaker (green), in general. This is true all across the brain.

It's like how when you're a kid, you play with the kids next door, but when you grow up you spend all your time on the internet talking to people thousands of miles away, and never speak to your neighbours. Kind of.

Link: Also blogged about here.

Dosenbach NU, Nardos B, Cohen AL, Fair DA, Power JD, Church JA, Nelson SM, Wig GS, Vogel AC, Lessov-Schlaggar CN, Barnes KA, Dubis JW, Feczko E, Coalson RS, Pruett JR Jr, Barch DM, Petersen SE, & Schlaggar BL (2010). Prediction of individual brain maturity using fMRI. Science (New York, N.Y.), 329 (5997), 1358-61 PMID: 20829489

You're (Brain Is) So Immature

How mature are you? Have you ever wanted to find out, with a 5 minute brain scan? Of course you have. And now you can, thanks to a new Science paper, Prediction of Individual Brain Maturity Using fMRI.

This is another clever application of the support vector machine (SVM) method, which I've written about previously, most recently regarding "the brain scan to diagnose autism". An SVM is a machine learning algorithm: give it a bunch of data, and it'll find patterns in it.

In this case, the input data was brain scans from children, teenagers and adults, and the corresponding ages of each brain. The pattern the SVM was asked to find was the relationship between age and some complex set of parameters about the brain.

The scan was resting state functional connectivity fMRI. This measures the degree to which different areas of the brain tend to activate or deactivate together while you're just lying there (hence "resting"). A high connectivity between two regions means that they're probably "talking to each other", although not necessarily directly.

It worked fairly well:

Out of 238 people aged 7 to 30, the SVM was able to "predict" age pretty nicely on the basis of the resting state scan. This graph shows chronological age against predicted brain age (or "fcMI" as they call it). The correlation is strong: r2=0.55.

The authors then tested it on two other large datasets: one was resting state, but conducted on a less powerful scanner (1.5T vs 3.0T) (n=195), and the other was not designed as a resting state scan at all, but did happen to include some resting state-like data (n=186). Despite the fact that these data were, therefore, very different to the original dataset, the SVM was able to predict age with r2 over 0.5 as well.

*

What use would this be? Well, good question. It would be all too easy to, say, find a scan of your colleague's brain, run it through the Mature-O-Meter, and announce with glee that they have a neurological age of 12, which explains a lot. For example.

However, while this would be funny, it wouldn't necessarily tell you anything about them. We already know everyone's neurological age. It's... their age. Your brain is an old as you are. These data raise the interesting possibility that people with a higher Maturity Index, for their age, are actually more "mature" people, whatever that means. But that might not be true at all. We'll have to wait and see.

How does this help us to understand the brain? An SVM is an incredibly powerful mathematical tool for detecting non-linear correlations in complex data. But just running an SVM on some data doesn't mean we've learned anything: only the SVM has. It's a machine learning algorithm, that's what it does. There's a risk that we'll get "science without understanding" as I've written a while back.

In fact the authors did make a start on this and the results were pretty neat. They found that as the brain matures, long-range functional connections within the brain become stronger, but short-range interactions between neighbours get weaker and this local disconnection with age is the most reliable change.

You can see this on the pic above: long connections get stronger (orange) while short ones get weaker (green), in general. This is true all across the brain.

It's like how when you're a kid, you play with the kids next door, but when you grow up you spend all your time on the internet talking to people thousands of miles away, and never speak to your neighbours. Kind of.

Link: Also blogged about here.

Dosenbach NU, Nardos B, Cohen AL, Fair DA, Power JD, Church JA, Nelson SM, Wig GS, Vogel AC, Lessov-Schlaggar CN, Barnes KA, Dubis JW, Feczko E, Coalson RS, Pruett JR Jr, Barch DM, Petersen SE, & Schlaggar BL (2010). Prediction of individual brain maturity using fMRI. Science (New York, N.Y.), 329 (5997), 1358-61 PMID: 20829489