Wednesday, 2 November 2011

Male-to-female transsexuals have "male" brains

People with "gender dysphoria" feel as though their sexual identity doesn't match their biological sex. A popular theory is that such people have a brain with physical characteristics that match the sex they identify with. So, for a man who feels like he is a woman - a male-to-female transsexual - the proposal is that he has a female brain "trapped" in a male body. Now in one of the first studies of its kind, Ivanak Savic and Stefan Arver have scanned the brains of 24 heterosexual, pre-operative male-to-female transsexuals and compared their structure to the brains of 24 heterosexual male and 24 heterosexual female controls. Homosexual transsexuals were omitted to help avoid the complicating influence of sexuality on the results. None of the transsexual participants had taken any hormone treatments, which is another factor that could have skewed the findings.

The scans threw up several of the structural brain differences associated with biological sex that have been reported before. For example, the men's brains had more grey matter in the cerebellum (involved in motor control) and lingual gyrus (involved in vision) and less gray matter and white matter in the precentral sulcus (part of the frontal lobe), compared with the women's brains. The men also had smaller hippocampi (involved in memory) than the women. In all these respects the brains of the male-to-female transexuals resembled the brains of the male control group. Likewise, the male-to-female transsexuals, like the male controls, had more asymmetric brains than the female controls. "The present study does not support the dogma that male-to-female transsexuals have atypical sex dimorphism in the brain but confirms the previously reported sex differences in structural volumes, gray, and white matter fractions," the researchers said. In other words, the male-to-female transsexuals may have felt like women, but their brains had structural characteristics typical of men.

But that's not to say that the male-to-female transsexual participants had brains that were unremarkable. Compared with the male and female controls, they had a smaller thalamus (the brain's relay centre) and putamen (an area involved in motor control) and increased gray matter in the right insula and inferior frontal cortex (regions involved in representing the body, among other functions). Savic and Arver advised treating these differences with caution. They've never been found before so need to be replicated with a larger sample. And even if confirmed, it's not clear what these differences mean, or whether they are a cause or consequence of gender dysphoria. "One highly speculative thought is that the enlargement of the ... insular and inferior frontal cortex ... could derive from a constant rumination about one's own body," the researchers said.

More research is needed, with larger samples and including studies of homosexual transsexuals and female-to-male transsexuals. "Any interpretation must, therefore, proceed cautiously and can at this point only be highly speculative," the researchers said.

ResearchBlogging.orgSavic, I., and Arver, S. (2011). Sex Dimorphism of the Brain in Male-to-Female Transsexuals. Cerebral Cortex, 21 (11), 2525-2533 DOI: 10.1093/cercor/bhr032

Post written by Christian Jarrett for the BPS Research Digest.


Anonymous said...

'"One highly speculative thought is that the enlargement of the ... insular and inferior frontal cortex ... could derive from a constant rumination about one's own body," the researchers said.'

I think they ought to have added a couple more 'highly's to that particular speculation, and maybe italicised them.

Rachel said...

Interesting, but the researchers use of the word "dogma", as well as their "speculations" seem to indicate potential bias. Pre-operative, non-hormonal hetrosexual trans women are not a representative group. Examination of at least the potential effects of hormones will be needed before any kind of conclusions can be drawn.

Ben said...

Certainly an interesting pioneer study, but, as the commenter above pointed out, the trans group doesn't appear representative of most 'trapped' trans; one would expect that a female 'trapped' in a male body would experience typical female sexuality i.e. sexual attraction to males, so these might be lesbians 'trapped' in a man's body?

I realise at this point this all becomes too philosophical and bizarre, but I wonder if the trans group found here would have a brain similar to that of a lesbian?

Or have I misunderstood what is meant by heterosexuality in this study? It does mean that the trans group are males attracted to females, does it not?

Liz Church said...

This article is deeply suspect. Anyone who uses language such as "male-to-female transsexual" when they mean "transwoman" is out of touch. Further, there is misgendering - "he" for a transfemale subject. What on earth does heterosexual mean in this context? Androphilic? Is more research is needed? Maybe, but by those without an agenda.

Unknown said...

The title of this article is misleading. 'Male to female transsexuals have male brains'? The text of the article does not say this. What the article says is that transsexual women have our own type of brains.

Ben said...

Oh dear, the science has already become overwhelmed by demands for political correctness.

Goodbye scientific integrity, goodbye quest for truth.

Unknown said...

hi Ben - thanks for your comments. Just to clarify, the male-to-female transexuals in this study were heterosexual in the sense that they were biologically male and sexually attracted to women.

L K Tucker said...

If a subject believed they were an extraterrestrial alien in a human body we would all recognize that as a bizarre belief and potentially psychotic. Bur there is a cultural, politically correct slant to the belief that someone is in the wrong sex body.

This study supports the conclusion that such beliefs are psychiatric rather than caused by a physical brain condition.

A simple problem discovered when it caused mental breaks for office workers has the ability tp subliminally shape thought and reason to create these beliefs.

In nine years investigating I found only one doctor aware Subliminal Distraction exists. He, like the designers and engineers who discovered the problem thinks it can only cause a harmless temporary episode of confusion.(Contact information available by request.)


Anonymous said...

science is not immune to political and social biases. we often look back on old theories and scoff at how clearly racial, sexual, and other biases stand out. it is important to be critical not only from a scientific standpoint from from a social and political standpoint. you can even look at a lot of popular evolutionary psychology claims that are circulating right now. part of it is the distortion that occurs when research goes mainstream, but part of it is from the biases of the researchers themselves. we are less likely to be critical of things that confirm our pre-existing biases. I am disappointed that so many intelligent, science-minded people refuse to recognize that they are, in fact, still people, who are just as prone to social conditioning as anyone else, or, even worse, who do not acknowledge the many flaws in society.

Jenna M said...

I am autogynephiliac and think it is an awesome finding, the MRI proves this is innate. The scientist have no explanation for the small thalamus or putman and they suggest repetitive thinking causes the enlarged inferior cortex and upper right ursala. Brain plasticity proves that when a brain is under developed or injhured in one are then other areas of the brain take up the slack and that is what we see happening here. Brain plasticity can not account for the small or underdeveloped thalamus or putman, however one would expect if these two parts of the brain were under developed then other parts would look over developed, that is exactly what we see in the MRI. And by the way, if any auotgynephilles come across this article do your self a favor and research the functions of theses parts of the brain for your self. Scientists really do not know what these parts of the brain are truly responsible for. The thalamus has multiple functions. Thalamus. A helpful way to remember is to think of the thalamus as a switchboard of information. The thalamus also plays an important role in regulating states of sleep and wakefulness. Thalamic nuclei have strong reciprocal connections with the cerebral cortex, forming thalamo-cortico-thalamic circuits that are believed to be involved with consciousness. Putman. While the putamen has many functions, it has been concluded that it has no specific specialization. However, since the putamen is interconnected with so many other structures, it works in conjunction with them to control many types of motor skills. These include controlling motor learning, motor performance and tasks,[3] motor preparation,[4] specifying amplitudes of movement,[5] and movement sequences. All I am saying is, read about these areas of the mind for yourself and most importantly, remember brain plasticity can not explain a smaller thalamus or putman.

Unknown said...

What? This post is about as bizarre as the first example attempt to give. However, I'll indulge it. As humans we have no foundation to understand what a completely different species experiences, we do however have a vast network of memories and experience that tell us what it is too be human. Furthermore, we begin to understand gender at a very young age...considering that we have a pretty developed knowledge of the gender spectrum and the binary we adhere too...nothing about they experiences of any gender is inherently alien to anyone. That said if a genetic male acts like a girl, feels like a girl, perceives things like a girl...knows they're a girl, well they probably are a girl. I for one am not going to argue against it; they know their life better than I do. As an outsider who am I to judge?

It's important to remember that gender is not sex. Male ≠ Man

You are, however, right in they fact that some of this condition/experience is psychological. The confusion and dysphoria created is caused when an individuals baseline attitude about themselves, and how they relate to others they inherently consider their peer group, dose not match up to the various other aspects of their biology (e.g. I'm cute, peppy and like ____ just like all those other girls...but gasp, i have a penis / ugly male body features / bald at 18 / hairy / bulky and masculine). That overwhelming and utterly defeated state of not being able to be yourself is an awful that can often lead a myriad of other compounding disorders or emotional handicaps and often suicide. It's not justifiable enough, or at all humane and constructive, to just right it off as a case of, "oh i think I'm a girl, but dur, I'm just stupid and confused!"

Lastly, I never fail to be struck by how ignorant or spiteful people can be on this subject. It gets so bad that some even hide behind the guise of science to justify the simple fact that they don't like transgenderism and it needs to be fixed and categorized into something I can understand and demonize of pity. That type of outlook is, insufferable! Why can't we just let people be who they are? Why, because it shatter our poorly constructed comfort zone when it comes to gender or is it because it's improper and corrupt and goes against natural design / god's law or is it because we want to try our hardest not to dole out insurance money to help them overcome such issues! It's hard enough for a transwoman to know that they are forever a male from a chromosomal stand point...don't rob them the dignity of people able to be called a woman. Anyone, anywhere should have the right to be / look however they want as long as it is not causing anyone unjust harm without having to be branded with some complicated medical status like a hospital bracelet or ID card; without having to be treated like a disease or monster. Societies approach to this, IMHO, is blatantly retarded.

Lastly to L K...who cares is someone dose feel like an extraterrestrial or an animal ( much like a furry)...If they have the money to cosmetically, and hopefully one day genetically, be close to that ideal and go through with it more power to them for living their life on their own terms and not for anyone else. I'm assuming you have never heard of transhumanism...but in the face of this movement, when i being to become more relevant as the technology and understanding to achieve it develop...i wonder how you repose would change?

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