title: 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.
abstract: OBJECTIVE
  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).
  
  
  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 cingulate 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 (Spearman's 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 deficient level of free T, the FtM transsexuals with normal range of free T showed significantly higher activities in the parahippocampal gyrus, hippocampus, insula, putamen, and amygdala during viewing female nude pictures (p < 0.005).
  
  
  CONCLUSIONS
  This study revealed the specific brain activation pattern associated with sexual orientation and its correlation with free T in the postoperative FtM transsexuals. These findings are applicable in understanding the neural mechanism on sexual arousal in FtM transsexuals and their sexual orientation in connection with the free T levels.
authors: Research Institute for Medical Imaging, Chonnam National University Medical School, Gwangju, 501-757, Republic of Korea.
authors: Gwang-Won
authors: GW
authors: Kim
authors: Department of Plastic and Reconstructive Surgery, Dong-A University School of Medicine, Busan, 602-715, Republic of Korea.
authors: Seok-Kwun
authors: SK
authors: Kim
authors: Research Institute for Medical Imaging, Chonnam National University Medical School, Gwangju, 501-757, Republic of Korea. gwjeong@jnu.ac.kr.|Department of Radiology, Chonnam National University Hospital, Chonnam National University Medical School, 42 Jebong-Ro, Donggu, Gwangju, 501-757, Republic of Korea. gwjeong@jnu.ac.kr.
authors: Gwang-Woo
authors: GW
authors: Jeong
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D057830:Gender-Affirming Surgery; D013739:Testosterone / Q000097:blood*; D063106:Transgender Persons / Q000523:psychology*; D014189:Transsexualism / Q000097:blood / Q000523:psychology*
chemical_list: D013739:Testosterone
keywords: Free testosterone; Postoperative FtM transsexuals; Sexual arousal; Sexual orientation; fMRI