The neuroscience of transgender identity: Transgender brains match their gender identity

This post is also available in Dutch.

Some people say they are “trapped” in the wrong body: They do not identify with the sex assigned to them at birth. There may be a neurobiological explanation to this feeling.

Just as faces can continuously change from male to female, there is no strict distinction between the female and male gender (Picture was created using FaceGen software).

Sex and Gender

“Sex” and “gender” are terms that describe different social realities, and therefore they can not be used interchangeably. “Sex” refers  to biological differences between females and males. According to GLAAD (Gay & Lesbian Alliance Against Defamation), gender  refers to the feeling of gender identity which is “an internal, personal sense of being a man or a woman”. Most people have a binary gender identity – the one of a man or a woman. However, there are some people for whom the sex assigned at birth and internal gender identity do not match. These people are called transgender. Gender identity is stable and rarely changes over time. Therefore, people who consider themelves transgender try to align their bodies with their mind via surgical interventions and / or hormonal treatment.

The neuroscience or gender identity

Is it possible to discover where or how the knowledge about one’s gender identity is represented? The investigations in this area are contradictory . It is still possible to conclude, however, that the brains of transgender people are more similar to the brains of the gender they identify with. In this study Sara M. Burke and Julie Bakker both affiliated with VU University Medical Center in Amsterdam performed an fMRI study on adolescent boys and girls before and after puberty diagnosed with gender dysphoria (previously called gender identity disorder) .

While in the MRI scanner, participants were exposed to androstadienone, a musky-smelling steroid produced by men, known to cause a different reaction in the hypothalamus of females and males. The researchers found that the brains of adolescents with gender dysphoria before puberty responded to androstadienone in a way compatible with their biological sex. After puberty the brain response was similar to the gender they experienced.

In other words, the hypothalamus of boys with gender dysphoria did not respond similarly to the odor in the way it that it responds to the odor in boys without dysphoria. For boys with gender dysphoria between 15 and 16 years-old, their hypothalamus would light up in the same way as the hypothalamus of heterosexual women. Meanwhile, heterosexual adolescent boys did not exhibit any activity in the hypothalamus. This indicates that after puberty the brain behaves according to the gender a person identifies with, even if their gender identity is different from that person’s sex.

Towards the neurobiological coding or gender identity

According to some experts, “sex differences in responding to odors can not be influenced by training or environment” (Dr. Baudewijntje Wrinkles  said in her interview to Scientific American). This is a strong claim that supports the idea that gender has a biological foundation. For people with gender dysphoria it may be useful to assess the gender they identify with using neuroimaging techniques such as fMRI. However, just as male and female brains, transgender brains can differ a great deal from one another. Therefore, it is still problematic to have a standard test when “scanning” for someone’s gender identity. In spite of this difficult task, it is not impossible to develop these tests in the future, once we learn  more about the neurobiology of transgender people.

For more information about gender dysphoria check out this link .

 

Written by Lara. Edited by Marisha.

 

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