Neural network of body representation differs between transsexuals and cissexuals.
Body image is the internal representation of an individual's own physical appearance. Individuals with gender identity disorder (GID), commonly referred to as transsexuals (TXs), are unable to form a satisfactory body image due to the dissonance between their biological sex and gender identity. We reasoned that changes in the resting-state functional connectivity (rsFC) network would neurologically reflect such experiential incongruence in TXs. Using graph theory-based network analysis, we investigated the regional changes of the degree centrality of the rsFC network. The degree centrality is an index of the functional importance of a node in a neural network. We hypothesized that three key regions of the body representation network, i.e., the primary somatosensory cortex, the superior parietal lobule and the insula, would show a higher degree centrality in TXs. Twenty-three pre-treatment TXs (11 male-to-female and 12 female-to-male TXs) as one psychosocial group and 23 age-matched healthy cissexual control subjects (CISs, 11 males and 12 females) were recruited. Resting-state functional magnetic resonance imaging was performed, and binarized rsFC networks were constructed. The TXs demonstrated a significantly higher degree centrality in the bilateral superior parietal lobule and the primary somatosensory cortex. In addition, the connectivity between the right insula and the bilateral primary somatosensory cortices was negatively correlated with the selfness rating of their desired genders. These data indicate that the key components of body representation manifest in TXs as critical function hubs in the rsFC network. The negative association may imply a coping mechanism that dissociates bodily emotion from body image. The changes in the functional connectome may serve as representational markers for the dysphoric bodily self of TXs.
Department of Dentistry, School of Dentistry, National Yang-Ming University, Taipei, Taiwan ; Integrated Brain Research Unit, Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan.
Chia-Shu
CS
Lin
Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan ; Integrated Brain Research Unit, Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan ; Department of Psychiatry, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan.
Hsiao-Lun
HL
Ku
Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei, Taiwan ; Department of Obstetrics and Gynecology, Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Hsiang-Tai
HT
Chao
Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan ; Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.
Pei-Chi
PC
Tu
Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan ; Department of Psychiatry, Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Cheng-Ta
CT
Li
Integrated Brain Research Unit, Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan.
Chou-Ming
CM
Cheng
Department of Psychiatry, Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan ; Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.
Tung-Ping
TP
Su
Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan ; Department of Psychiatry, Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Ying-Chiao
YC
Lee
Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan ; Integrated Brain Research Unit, Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan.
Jen-Chuen
JC
Hsieh
D000328:Adult; D001828:Body Image; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000503:physiopathology*; D013003:Somatosensory Cortex / Q000503:physiopathology*; D014189:Transsexualism / Q000503:physiopathology*; D055815:Young Adult