BiGender and the Brain

Gender-Typical Behaviour Patterns, Sexual Orientation and Gender Identity are set in Neurology.

Cross-Gendered (CG) Sexual Orientation is an unsubtle effect, and often associated with cross-gendered behaviour patterns in young children. It appears to be set by pre-natal hormone influences.

CG Gender Identity is also set by pre-natal influences. The effects appear later, and the tell-tale neurology appears after Gender Identity is formed. But the pattern that dictates the later neurological development is just as pre-ordained. It is a more subtle effect that sexual orientation, and many people are essentially Bi-Gendered, and would be able to function in either a male or female role, as circumstances dictate. Relatively few are strongly gendered, but for those that are, it's unchangeable. Just as CG sexual orientation is strongly correlated with CG behaviour in children, CG gender identity is universally(?) associated with CG patterns of thought in children.

CG somatic form due to pre-natal hormonal exposure is more strongly correlated with CG sexual orientation than with CG gender identity. It is thus more strongly correlated with CG behaviour. CG sexual orientation is rather more weakly correlated with CG somatic form and CG gender identity, and so all but a few who have CG sexual orientation have perfectly normal somatic form and gender identity. CG somatic form is more strongly correlated with CG gender identity (by a factor of 30), but still the majority (90%?) of physically intersexed people have normal gender identities.

CG gender identity is moderately correlated with CG sexual orientation, by a factor of about 3-5. So while most gays are not transsexual, about 1/3-1/2 of transsexuals have CG sexual orientation in addition to CG gender identity.

Some pieces of the puzzle that led me to these conclusions:

From the Grauniad :

Striking similarities between the brains of gay men and straight women have been discovered by neuroscientists, offering fresh evidence that sexual orientation is hardwired into our neural circuitry.

Scans reveal homosexual men and heterosexual women have symmetrical brains, with the right and left hemispheres almost exactly the same size. Conversely, lesbians and straight men have asymmetrical brains, with the right hemisphere significantly larger than the left.

Scientists at the prestigious Stockholm Brain Institute in Sweden also found certain brain circuits linked to emotional responses were the same in gay men and straight women.

The findings, published tomorrow in the US journal Proceedings of the National Academy of Sciences, suggest the biological factors that influence sexual orientation - such as exposure to testosterone in the womb - may also shape the brain's anatomy.

The study, led by the neurobiologist Ivanka Savic, builds on previous research that has identified differences in spatial and verbal abilities related to sex and sexual orientation. Tests have found gay men and straight women fare better at certain language tasks, while heterosexual men and lesbians tend to have better spatial awareness.

Savic and her colleague Per Linström took MRI brain scans of 90 volunteers who were divided into four groups of similar ages according to whether they were male, female, heterosexual or homosexual. The scans showed the right side of the brain in heterosexual men was typically 2% larger than the left. Lesbians showed a similar asymmetry, with the right hand side of the brain 1% larger than the left.

Scans on homosexual men and heterosexual women revealed both sides of the brain were the same size.
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Savic's team has yet to confirm whether the differences in brain shape are responsible for sexual orientation, or are a consequence of it.
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"These differences might be laid down during brain development in the womb, or they could happen after birth, though it could very likely be a combination of the two," said Savic.

In another series of tests, Savic and Lindström used a technique called positron emission tomography (PET) to look at brain wiring in a smaller group of volunteers. They found heterosexual women and gay men shared brain circuitry linking a region called the amygdala, which plays a key role in emotional responses, to other parts of the brain.

Note though A Sex Difference in the Human Brain and its Relation to Transsexuality by Zhou et al.

The BSTc volume in heterosexual men was 44% larger than in heterosexual women. The volume of the BSTc of heterosexual and homosexual men was found not to differ in any statistically significant way. The BSTc was 62% larger in homosexual men than in heterosexual women. A small volume of the BSTc was found in the male-to-female transsexuals. Its size was only 52% of that found in the reference males and 46% of the BSTc of homosexual males.

There's also Male-to-Female Transsexuals Have Female Neuron Numbers in a Limbic Nucleus by Kruijver et al:

The number of SOM neurons in the BSTc of heterosexual men (32.9 ± 3.0 x 103) was 71% higher than that in heterosexual women (19.2 ± 2.5 x 103), whereas the number of neurons in heterosexual and homosexual men (34.6 ± 3.4 x 103) was similar. The BSTc number of neurons was 81% higher in homosexual men than in heterosexual women. The number of neurons in the BSTc of male-to-female transsexuals was similar to that of females (19.6 ± 3.3 x 103). In addition, the neuron number of the FMT (the single female to male transsexual) was clearly in the male range. The number of neurons in transsexuals was 40% lower than that found in the heterosexual reference males and 44% lower than that found in the homosexual males.
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There seemed to be no clear difference in the BSTc number of neurons between early onset and late-onset transsexuals, indicating that their smaller number of neurons is related to the gender identity per se rather than to the age at which it became apparent.

This means that different parts of the brain are associated with cross-gendered sexuality, and cross-gendered gender identity. In some parts of the brain, heterosexual men and lesbian women share one pattern, and homosexual men and heterosexual women the other. In other parts, all men regardless of sexual orientation share one pattern, and women share the other. It is in at least one area like this that transsexual women (ie those born looking male) share the female pattern, and transsexual men the male one.

Sexual Orientation and Gender Identity are different.

I'd better explain diagramatically.

Image: http://www.howstuffworks.com

The limbic system, which is associated with emotions, lies in both hemispheres. It includes the hypothalamus, hippocampus, amygdala, pituitary gland, and several other areas. The BSTc is a tiny piece of the hypothalamus.

Neurologically, sexual orientation is associated with relatively major cross-gendering. Lots of parts are affected. Who we are attracted to is a big part of our brain's makeup. Gender Identity, on the other hand, who we see ourselves as, is rather more subtle. Its marker is a tiny piece of a relatively small part of the brain. I say "marker", because the differences in the BSTc layer only become apparent at puberty, yet gender identity is set well before that.

Another part of the puzzle, as I've blogged about before :

Twelve heterosexual men and twelve heterosexual women were examined, along with twelve anatomical males who identify as women. As Dr. Elke Gizewski stressed at the Röntgenkongreß in Berlin, it was already well-known from preliminary investigations of other groups that differences between men and women appear in fMRT when they are presented with erotic stimuli.

In men, the limbic system and upper regions of the hypothalamus, the amygdalae and the insular cortex were activated substantially more strongly. “We confirmed this finding in the comparison between the heterosexual men and women of our Cohort”, said Gizewski.

This specifically male activation of the limbic system was not found in the transsexual sample. Under fMRT, the pictures corresponded rather accurately to those of the female sample.

Radiologists can now confirm what transsexuals report - that they feel “trapped in the wrong body” - on the basis of the activation of the brain when presented with erotic stimuli. There is obviously a biological correlation with the subjective feelings.

I also gave the critique:

It may be that the sample of transsexual women were all Hetero, none Lesbian. If so, it may only prove a biological basis for sexual preference, rather than gender as such.

I now think this is more likely, as the sexual orientation difference would be far more obvious (in light of the Swedish results) than the relatively subtle Gender Identity one. UPDATE: But see this comment : "The german study had M2F of different sexual orientation".

There's some more parts of the puzzle. First, let's see if the lateralisation, the differentiation between hemispheres that is correlated with sexual orientation, is affected by pre-natal hormones. From Prenatal exposure to testosterone and functional cerebral lateralization: a study in same-sex and opposite-sex twin girls. by Cohen-Bendehan et al:

In animals it has been shown that exposure to sex hormones is influenced by intrauterine position. Thus fetuses located between two male fetuses are exposed to higher levels of testosterone (T) than fetuses situated between two female fetuses or one female and one male fetus. In a group of opposite-sex (OS) twin girls and same-sex (SS) twin girls a potential effect of prenatal exposure to testosterone (T) on functional cerebral lateralization was investigated. We hypothesized that prenatal exposure to T would result in a more masculine, i.e. a more lateralized pattern of cerebral lateralization in OS twin girls than in SS twin girls...Compared with SS girls, OS twin boys showed a more lateralized pattern of processing verbal stimuli. Secondly, as predicted OS girls had a more masculine pattern of cerebral lateralization, than SS girls. These findings support the notion of an influence of prenatal T on early brain organization in girls.

So pre-natal exposure to excess testosterone will partly masculinise female neurology.

Let's look at what happens with pre-natal exposure to powerful Estrogens. From Prenatal exposure to diethylstilbestrol(DES) in males and gender-related disorders:results from a 5-year study by Scott Kerlin. (available here, and a prelininary paper here. :

More than 150 network members (out of 500) with “confirmed” or “strongly suspected” prenatal DES exposure identified as either “transsexual, pre- or post-operative,” (90 members), “transgender” (48 members), “gender dysphoric” (17 members), or “intersex” (3 members).
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In this study, more than 150 individuals with confirmed or suspected prenatal DES exposure reported moderate to severe feelings of gender dysphoria across the lifespan. For most, these feelings had apparently been present since early childhood. The prevalence of a significant number of self-identified male-to-female transsexuals and transgendered individuals as well as some individuals who identify as intersex, androgynous, gay or bisexual males has inspired fresh investigation of historic theories about a possible biological/endocrine basis for psychosexual development in humans, including sexual orientation, core gender identity, and sexual identity (Benjamin, 1973; Cohen-Kettenis and Gooren, 1999; Diamond, 1965, 1996; Michel et al, 2001; Swaab, 2004).

Now look at what happens with gender identity in those who naturally "change sex". Those born with 5ARD or 17BHDD are feminised to some degree at birth, and masculinise to some degree at puberty. I feel an affinity for them, in view of my own change in the opposite direction. From Gender change in 46,XY persons with 5alpha-reductase-2 deficiency and 17beta-hydroxysteroid dehydrogenase-3 deficiency. by Cohen-Ketternis:

Individuals with 5alpha-reductase-2 deficiency (5alpha-RD-2) and 17beta-hydroxysteroid dehydrogenase-3 deficiency (17beta-HSD-3) are often raised as girls. Over the past number of years, this policy has been challenged because many individuals with these conditions develop a male gender identity and make a gender role change after puberty. The findings also raised doubts regarding the hypothesis that children are psychosexually neutral at birth and emphasized the potential role of prenatal brain exposure to androgens in gender development. If prenatal exposure to androgens is a major contributor to gender identity development, one would expect that all, or nearly all, affected individuals, even when raised as girls, would develop a male gender identity and make a gender role switch later in life. However, an estimation of the prevalence of gender role changes, based on the current literature, shows that gender role changes occur frequently, but not invariably. Gender role changes were reported in 56-63% of cases with 5alpha-RD-2 and 39-64% of cases with 17beta-HSD-3 who were raised as girls. The changes were usually made in adolescence and early adulthood. In these two syndromes, the degree of external genital masculinization at birth does not seem to be related to gender role changes in a systematic way.

So about half to 2/3 changed gender roles to male as their bodies masculinised. But the degree of their bodies' cross-gendering was no guide at all as to who would do what. This is consistent with about 1/3 being strongly gendered female, 1/3 strongly gendered male, and 1/3 bi-gendered, "going with the flow".

So how do we know our Gender Identity, if it's such a relatively subtle effect? From Biased-Interaction Theory of Psychosexual Development: “How Does One Know if One is Male or Female?” by Diamond:

A theory of gender development is presented that incorporates early biological factors that organize predispositions in temperament and attitudes. With activation of these factors a person interacts in society and comes to identify as male or female. The predispositions establish preferences and aversions the growing child compares with those of others. All individuals compare themselves with others deciding who they are like (same) and with whom are they different. These experiences and interpretations can then be said to determine how one comes to identify as male or female, man or woman. In retrospect, one can say the person has a gendered brain since it is the brain that structures the individual’s basic personality; first with inherent tendencies then with interactions coming from experience.
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Starting very early in life the developing child, consciously or not, begins to compare himself or herself with others; peers and adults seen, met, or heard of. All children have this in common (R. Goldman & J. Goldman, 1982). In so doing they analyze inner feelings and behavior preferences in comparison with those of their peers and adults. In this analysis they crucially consider “Who am I like and who am I unlike?” Role models are of particularly strong influence but there is no way to predict if a model will be chosen, who will be chosen, nor on what basis chosen. In this comparison there is no internal template of male or female into which the child attempts to fit. Instead they see if they are same or different in comparisons with peers, important persons, groups or categories of others (Diamond, 2002b). It is the “goodness of fit” that is crucial. The typical boy, even if he is effeminate, sees himself as fitting the category “boy” and “male” and eventually growing to be a man with all the accoutrements of masculinity that go with it. Similarly the typical girl, even if quite masculine, grows to aspire being a woman and probably being a mother. The comparisons allow for great flexibility in cultural variation in regard to gendered behaviors. It is the adaptive value of this inherent nature of brain development that trumps a concept of a male–female brain template to organize gender development. The average male fits in without difficulty, the atypical one who will exhibit signs of gender identity dysphoria, for instance, does not see himself as same or similar to others of his gender. He sees himself as different in likes and dislikes, preferences and attitudes but basically in terms of identity. There will be a period of confusion during which the child thinks something like Mommy and Daddy call me boy, and yet I am not at all like any of the others that I know who are called “boy.” While the only other category the child knows is girl, he develops the thought that he might be or should be one of those. Initially that thought is too great a concept leap to be easily accepted and the child struggles in an attempt to reconcile these awkward feelings. The boy might actually imagine he is, if not really a boy than possibly an it, an alien of some sort or a freak of nature. Eventually he might come to believe, since he knows of no other options, that he is a girl or should be one. And with a child’s way of believing in Santa Claus or the Tooth Fairy he can come to expect he will grow up to be a woman. With experience and the realization that this won’t happen of its own accord the maturing child may begin to seek ways to effect the desired change. A female can experience an opposite scenario.

I'd seen the abstract back in March, but hadn't got access to the full article until recently. It was hard for me to read, and I shed a few tears while doing it. Because just a few weeks before I read it, this is what I wrote at Bilerico.

Of our trans folk, how old were you when you realized that you were transgender?...I'm interested in how old you were when you really started gender bending; were you a child or an adult?

Two separate questions there.

Of our trans folk, how old were you when you realized that you were transgender?

Up until age 5, I was a child. No real concept of gender.

At 6, I went to school, and noticed something was wrong. I was dressed as a boy, I looked like a boy, but I didn't think like "other boys". I still liked toy guns, and Meccano rather than dolls, but I was different.

At 7, I knew I wasn't a boy, but didn't know what I was. I thought boys were puerile, and girls too silly and sissy. A classic Tomboy in retrospect.

At 8, I got to play hopscotch with other girls, and I felt at home. They thought like I did, they cried like I did. I still didn't see myself as more than an honourary girl though. Even if my favourite toy car was Lady Penelope's pink Rolls-Royce.

At 9, more by a process of elimination than anything else, I realised I was female. Boys could just as well have been an alien species. Girls were just like me, in feelings and values.

At 10, I was in a boys boarding school then, and I was able to make up boardgames of astounding complexity when it rained. I had my own secret garden in the nearby woods, with flowerbeds I'd planted. I could sit and read amidst the flowers, and was terribly happy. It was then I picked the name Zoe, and planned what I was going to do with my life. I wanted children, a husband, the white picket fence etc, but also to be a Rocket Scientist and to travel the world, things that Wives and Mothers Just Did Not Do in the 60's.

Even though it had been obvious since age 7 that I’d never be “svelte” or “petite”, that I’d be the girl “with the wonderful personality”. I didn’t cry about that – much. And not where anyone could see me. I was more worried about the practical problems I'd be having when I started having a female puberty. And vaguely concerned that boys didn't interest me at all. I was no naive I thought that was part of the package of being a girl. Was I a defective one?

It came as a terrible shock when I learnt that boys and girls are born looking different, and that my body was boy.

I didn’t take it well.

Basically, I failed my SAN roll, and convinced myself I had to be a boy, no matter how I felt inside. That meant forgetting a lot, suppressing memories, but it was either acquire a minor psychosis, or sink into despair, depression, and death.

A part of me still knew, but that part was in a box in a safe in the hold of a sunken ship at the bottom of the ocean on a planet circling a distant star.

I tried to be the best Man any woman could be. I did that for 47 years. It helped to be Asexual, mildly lesbian if anything. Sex was for having children, a form of cuddling and pleasing someone you loved, albeit a bit tiring after the first hour. Not something instinctive or natural.

You can see why the paper had such a powerful effect on me. It was my story. To continue:

how old you were when you really started gender bending

I didn't. Or I always did. It turned out I was Intersexed, with "severe androgenisation of a non-pregnant woman". How severe? Well, I never had a working female reproductive system (nor a fully functional male one), but with some technical help became a biological father in 2001. That severe.

In May 2005, my male appearance started changing, and by late July, I could no longer pass as male. Nor did I want to, that box I'd put my feelings in exploded at the first sign that I wasn't male after all. By mid August 2005, I was fulltime, name changed, drivers licence changed, bank details changed... December 2005 I saw a gender specialist shrink, and in February 2006 had retrospective permission for the HRT my endo had put me on to stabilise my body, and permission for surgery too. Things were a bit of a mess down there by then, and the surgeon had to be creative in November 2006. I'm happy with the result, and so is my OB/GYN.

I had just about gotten over the realisation I'd had a lesbian love life all my life, when that started changing, and boys started looking really interesting and kinda cute. That happens sometimes. Never thought it would happen to me though. I'm still getting used to it. I'd always been anorgasmic - defective male peripherals didn't work too well with female device drivers. Enough to please, but not be pleased. Now things are normal. As in OMG!!!!!!!!!!!!! Now I understand what all the fuss was about. Wow. WOW!. I never suspected... Too bad the love of my life, the woman I'm married and partnered to is the wrong sex - and I'm the wrong sex for her. It's too ironic, and too tragic, that we are married but not attracted to one another, while others who are attracted to one another can't marry. That's wrong.

Up until the time my body started changing, my story follows the "classic transsexual narrative" so closely it's almost a cliche. And there was I thinking I at least was unique. HA! If anything, I was less feminine than most. Many know at age 3. And I first dressed in female attire only 3 weeks before "going fulltime".

So call me TS with IS complications, or IS with a TS history, just don't call me late for dinner.

It's difficult being dispassionate when you're your own experimental animal.

I won't go into the the detail of the results from Zucker et al regarding their experimental treatment of children presenting with "Gender Identity Disorder". Just that of those showing CG behaviour, about a third have CG Gender Identity, and the rest CG sexual orientation later in life. (1/3 being strongly gendered female, 1/3 strongly gendered male, and 1/3 bi-gendered, "going with the flow", remember?) See my posts Sex and the Brain, Square Peg, Round Hole, Mommy, Don't Take me There, and Transsexual Causation, the American Psychiatric Association, and Interpol.

One final thing. About the experience of a child who is "different". Here's the other part of my personal history.

One thing I didn't mention: the penalty for being "different" at grade school. A recent CAT scan showed the damage to my skull from the time somebody used a crowbar to assault me. The scars from the cigarette burns on my hands and neck faded long ago, and besides which, I was older then, 14 not 8.

You gave to remember I was big for my age, built like a quarterback, and so didn't get picked on nearly as much as others did. I was able to fight back, unless there were too many of them. Then I'd pick one, usually the weakest, and make sure he got hurt as badly as I did, or worse. Next time, the gang would have one less member, and I'd repeat the process. Eventually that particular gang would give up, and go looking for easier prey.

The gang with the crowbar blindsided me, and I think they got scared when they saw what they'd done. I don't know, memories are fuzzy there. I was 8 at the time.

At puberty, well, I didn't have a complete one of those anyway, so went from being one of the tallest kids in the class to being one of the shortest. And by that time, I appeared to be just another nerd. Inside school I was safe. Going home, not so much, hence the strangulation and burns.

And my hugs and sympathies to all those who went through this, just about all of whom had it far, far worse than I did. That's why we all want to move heaven and Earth to make sure no other kids go through that. So many don't make it, and kill themselves, be it by drugs, alcohol, or a bullet. God only knows how we survived. But then, so many of us didn't. How many are still in institutions, their brains fried by electroshock and psychotropic drugs 40 years ago?

So now you know what spurs not just my desire to know about all this, but to gain decent treatment for those whose neurology is not quite the standard model. It's for the little girl I was, back in the 60's and 70's. The one who was spat on and urinated on for hours, in a boat where to fight back would mean everyone being dumped in the water with the sharks. God, I got off lightly compared with so many others!