Oestrogens are Not Related to Emotional Processing: a Study of Regional Brain Activity in Female-to-Male Transsexuals Under Gonadal Suppression

Although the prevailing opinion is that emotional processes are influenced by sex hormones, the literature is still inconclusive. The aim of the current study was to examine the effects of gonadal suppression on brain activity during affective picture processing. Twenty-one female-to-male (FtM) transsexuals and 19 control women were recruited and underwent functional magnetic resonance imaging scanning while rating emotional pictures adapted from the International Affective Picture System. The gonadal hormone production of the FtMs was suppressed for 8 weeks, the control group did not receive any treatment before scanning. Under gonadal suppression, FtMs showed less brain activation in the superior temporal lobe compared with female controls during perception of positive affective pictures. Regression analysis showed that during processing of positive affective images, brain activity within the right superior temporal lobe was not correlated with levels of estradiol, luteinizing hormone, and follicle-stimulating hormone. In the absence of associations with hormonal levels, the difference in activation in the superior temporal lobe during positive emotional stimuli between FtMs and control women may be attributed to a priori differences between the 2 groups. Future studies should clarify if these differences are a result of atypical sexual differentiation of the brain in FtMs.