Neural network of body representation differs between transsexuals and cissexuals

PLoS One. 2014 Jan 20;9(1):e85914. doi: 10.1371/journal.pone.0085914. eCollection 2014.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Body Image*
  • Brain Mapping
  • Female
  • Humans
  • Image Processing, Computer-Assisted
  • Magnetic Resonance Imaging
  • Male
  • Nerve Net / physiopathology*
  • Somatosensory Cortex / physiopathology*
  • Transsexualism / physiopathology*
  • Young Adult

Grant support

This work was supported by the National Science Council (99-2314-B-075-018), the Taipei Veterans General Hospital (V100E3-002, V101C-201 and V101E3-002), the Brain Research Center of National Yang-Ming University (98A-C-B501_23) and the Aim for the Top University Plan of the Ministry of Education for National Yang-Ming University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.