Neural activation-based sexual orientation and its correlation with free testosterone level in postoperative female-to-male transsexuals: preliminary study with 3.0-T fMRI

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Web End = Surg Radiol Anat (2016) 38:245252 DOI 10.1007/s00276-015-1547-z

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Web End = Neural activation-based sexual orientation and its correlation with free testosterone level in postoperative female-to-male transsexuals: preliminary study with 3.0-T fMRI

Gwang-Won Kim1 Seok-Kwun Kim2 Gwang-Woo Jeong1,3

Received: 27 December 2014 / Accepted: 17 August 2015 / Published online: 29 August 2015 Springer-Verlag France 2015

AbstractPurpose The purpose of this study was to evaluate the brain activation pattern associated with sexual orientation and its correlation with the level of the free testosterone (free T) in postoperative female-to-male (FtM) transsexuals using a 3.0-Tesla functional magnetic resonance imaging (fMRI).

Materials and methods Eleven postoperative FtM transsexuals with sex reassignment surgery underwent fMRI on a 3.0-T MR scanner. Brain activity was measured while viewing erotic male and female nude pictures.

Results The average level of free T in the FtM transsexuals was in the normal range of heterosexual men. The brain areas with predominant activities during viewing female nude pictures in contrast to male pictures included the hippocampus, parahippocampal gyrus, anterior cingu-late gyrus, putamen, amygdala, hypothalamus, and insula (p \ 0.005). The free T levels were positively correlated with the BOLD signal changes in the parahippocampal gyrus (Spearmans rho = 0.91, p \ 0.001), hippocampus (rho = 0.90, p \ 0.001), insula (rho = 0.68, p \ 0.05), putamen (rho = 0.66, p \ 0.05), and amygdala (rho =

0.64, p \ 0.05). Compared to FtM transsexuals with decient level of free T, the FtM transsexuals with normal range of free T showed signicantly higher activities in the parahippocampal gyrus, hippocampus, insula, putamen, and amygdala during viewing female nude pictures (p \ 0.005).

Conclusion This study revealed the specic brain activation pattern associated with sexual orientation and its correlation with free T in the postoperative FtM transsexuals. These ndings are applicable in understanding the neural mechanism on sexual arousal in FtM transsexuals and their sexual orientation in connection with the free T levels.

Keywords Postoperative FtM transsexuals Sexual

arousal Free testosterone Sexual orientation fMRI

Introduction

Transsexualism is a gender identity disorder...