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Sunday, June 1, 2008

Caroline's "Research on Transsexual Brain Signature Simplified"

See the original paper, Brain Signature Characterizing the Body-Brain-Mind Axis of Transsexuals, at PLOS|ONE, by clicking here.

Here is Caroline's analysis in its entirety:

So you have spent a lifetime thinking that your body is wrong for what your brain tells you who and what you should be.
Are you crazy? If like me you knew that you were not crazy, clinical help which involved psychiatric tests always seemed like a stupid idea! It has been known for a long time that there are measurable differences between a transsexual’s brain and that of someone born with a similar body. The only problem is that to do the test you have to be dead and the deepest parts of your brain have to be cut into very thin slices and viewed under a microscope. Not a test many would put their hand up for though I had considered leaving my brain to science just to prove that I had been right all along...
The very machines which your local hospital uses to have a look inside you to see if all is working as it should are now being regularly used to see which parts of the brain are active during various kinds of stimulus.
As transsexuals we believe that we should have been born with the opposite body to the one we got because our brains do not fit our expected gender role, cross sex identification. At last a group of researchers have been smart enough to do a study to see if we were right!
They found 21 FTMs and 20 MTFs with some receiving appropriate hormone treatments and others untreated, and a control group with no gender dysphoria. All including the control group were given standard regular psychiatric diagnostic interviews according to the DSM-IV. Participants’ sexual orientation and medical histories, moods and their psychosocial defences were assessed using clinical interviews They were also evaluated regarding the level of their self-identification which they rated on a scale 1 to 10, ie none to maximum possible:-
Self-identification as the opposite sex (IOS), “Please rate the degree to which you identify yourself as another gender opposite to your biological sex.
The desire to become the opposite sex (DOS), “Please rate the degree to which you desire to become another gender opposite to your biological sex.
Rigorous interview methods were used to ensure that answers were consistent from individuals and the results were interesting though to us probably expected.

The transsexual group compared to the control group reported very high levels of IOS and DOS .

The participants watched 4 silent erotic and 4 silent neutral films (30-sec duration each) in a balanced semi-randomized order. These films (maximized for arousal and minimized for disgust in the E-films; minimized for eliciting emotion in the N-films) were randomly chosen from a database of films which had been previously validated with other groups of transsexuals and controls. The erotic films contained scenes of male-female genital intercourse in the nude, whereas the neutral films contained scenes of common male-female dialogue in regular clothing. Again participants used a 0 = none and 10 = the maximum imaginable scoring scale. Immediately after each film, the participants rated their erotic arousal (arousal score) according to the statement “Please rate the degree to which you felt sexually aroused when watching this film” and the extent to which they felt embodied as male/female (selfness score) according to the statement “Please rate the degree to which you identify yourself as the male/female in the film.” For this study they were mainly interested in comparing one group (MTFs and FTMs combined) to the control group (heterosexual males and females combined), which was also justified by the fact that neither MTFs, FTMs nor female and male controls differed in age or education.
All groups rated higher levels of arousal for the erotic-films compared to the neutral-films and all groups rated higher levels of selfness ) when they identified themselves as the desired genders vs. the un-desired genders while watching the erotic-films.
Compared to the control, transsexuals rated higher selfness scores for their desired gender when watching the erotic films. Notably, transsexuals demonstrated significantly higher selfness scores when they saw themselves as their desired gender vs. un-desired gender while watching the neutral films. In contrast, the controls did not show such significant differences when compared to the transsexuals for the neutral films and reported much lower selfness scores for the desired genders when watching the neutral films.


23 from the transsexual group were age matched with 23 from the control group to have MRI scans of their brain activity to see how they react to various kinds of stimulus. This is something over which the participants have no control, this is how their very being reacts to the world...
None of the females or FTMs were ovulating or pregnant during the study period, and participants abstained from sexual behaviour the day prior to the scan part of the experiment.
The results showed neurobiological factors that underpin the spectrum of gender identity. Neuroimaging studies revealed an association of transsexualism with functional and structural changes of the brain. In addition, the pattern of brain activity in transsexuals was demonstrated to substantially overlap with that of their desired genders when they encounter gender-related stimuli, such as visual erotic stimuli or odorous steroids.
Anatomically, it has been reported that a female-sized bed nucleus of the stria terminalis was found in the MTFs. An additional study showed that the volume and neuron number of the interstitional nucleus of the anterior hypothalamus, of MTFs were similar to those of control females, and that those of one FTM fell within the range of control males. It has also been demonstrated that transsexualism can be associated with a different cerebral gray-matter pattern from that of controls . These findings suggest that brain anatomy may play a role in gender identity. Diffusion tensor imaging studies have also revealed that the white matter microstructural patterns in untreated FTMs are closer to the patterns of subjects who share their gender identity than those who share their biological sex. These findings suggest that TXs and non-TX controls differ in neuroanatomical feature. Furthermore, it has been reported that MTFs may be associated with sex-atypical neuronal responses in specific hypothalamic circuits during odorous stimulation of gonadal hormones with pheromone-like properties, possibly as a consequence of variant neuronal differentiation. MTFs may manifest brain activation pattern overlapping that of normal females during the viewing of erotic stimuli.

Collectively, these findings indicate that GID is characterized by structural and functional alterations in the brain.
Central to the psychological complex of transsexuals is the conviction of belonging to the opposite sex, i.e., a conspicuous incongruence between their desired psychological gender and un-desired biological sex. This fact was evidenced by the very high ratings of IOS and DOS given by transsexuals in the clinical assessments. Behaviorally, transsexuals demonstrated high saliency of their desired gender in both erotic and neutral conditions while the controls did so only in erotic situations. 

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