BNST stands for the central region of the bed nucleus of the stria terminalis. It is located in the hypothalamus, a source of many hormones for the body, along with controlling other things like sex and anxiety responses. When comparing cisgender female and male BNST, it is found that males are twice the size than females. “Likewise, the BNST in the brains of transgender females- individuals with males external anatomy, but who have lifelong female gender identification- look exactly like the BNST in the brains of those with female genitalia and reproductive organs, that is, smaller than a man’s. Interestingly, these differences hold whether the transgender individual has undergone sex reassignment surgery, hormonal treatment, both, or neither. Likewise, when scientist autopsied the brains of patients whose testicular cancer was treated with heavy does of the feminizing hormone estrogen, they found no shrinkage of these men’s BNST.” -Page 160.
I knew that there were brain structures and cell differences in brains, but in most places it was unclear where exactly it originates. After reading this, it made a whole lot more sense to me and helped me provide further scientific evidence for my little book label, along with the long list of critique I received Thursday.
My wondering for this week is: since being transgender is about brain structure, this abnormality must happen in the womb. What neurotransmitter (etc) starts this process? Does the mother play a part in it?