- Burke Sarah M, Manzouri Amir H, Dhejne Cecilia, Bergström Karin, Arver Stefan, Feusner Jamie D, Savic-Berglund Ivanka Testosterone Effects on the Brain in Transgender Men Cerebral cortex (New York, N.Y. : 1991), 2017; 1-15.
Transgender individuals experience incongruence between their gender identity and birth-assigned sex. The resulting gender dysphoria (GD), which some gender-incongruent individuals experience, is theorized to be a consequence of atypical cerebral sexual differentiation, but support for this assertion is inconsistent. We recently found that GD is associated with disconnected networks involved in self-referential thinking and own body perception. Here, we investigate how these networks in trans men (assigned female at birth with male gender identity) are affected by testosterone. In 22 trans men, we obtained T1-weighted, diffusion-weighted, and resting-state functional magnetic resonance imaging scans before and after testosterone treatment, measuring cortical thickness (Cth), subcortical volumes, fractional anisotropy (FA), and functional connectivity. Nineteen cisgender controls (male and female) were also scanned twice. The medial prefrontal cortex (mPFC) was thicker in trans men than controls pretreatment, and remained unchanged posttreatment. Testosterone treatment resulted in increased Cth in the insular cortex, changes in cortico-cortical thickness covariation between mPFC and occipital cortex, increased FA in the fronto-occipital tract connecting these regions, and increased functional connectivity between mPFC and temporo-parietal junction, compared with controls. Concluding, in trans men testosterone treatment resulted in functional and structural changes in self-referential and own body perception areas.
- Feusner Jamie D, Lidström Andreas, Moody Teena D, Dhejne Cecilia, Bookheimer Susan Y, Savic Ivanka Intrinsic network connectivity and own body perception in gender dysphoria Brain imaging and behavior, 2016; 20(3)
Gender dysphoria (GD) is characterized by incongruence between one's identity and gender assigned at birth. The biological mechanisms of GD are unclear. We investigated brain network connectivity patterns involved in own body perception in the context of self in GD. Twenty-seven female-to-male (FtM) individuals with GD, 27 male controls, and 27 female controls underwent resting state fMRI. We compared functional connections within intrinsic connectivity networks involved in self-referential processes and own body perception -default mode network (DMN) and salience network - and visual networks, using independent components analyses. Behavioral correlates of network connectivity were also tested using self-perception ratings while viewing own body images morphed to their sex assigned at birth, and to the sex of their gender identity. FtM exhibited decreased connectivity of anterior and posterior cingulate and precuneus within the DMN compared with controls. In FtM, higher "self" ratings for bodies morphed towards the sex of their gender identity were associated with greater connectivity of the anterior cingulate within the DMN, during long viewing times. In controls, higher ratings for bodies morphed towards their gender assigned at birth were associated with right insula connectivity within the salience network, during short viewing times. Within visual networks FtM showed weaker connectivity in occipital and temporal regions. Results suggest disconnectivity within networks involved in own body perception in the context of self in GD. Moreover, perception of bodies in relation to self may be reflective rather than reflexive, as a function of mesial prefrontal processes. These may represent neurobiological correlates to the subjective disconnection between perception of body and self-identification.
- Feusner Jamie D, Dervisic Jasenko, Kosidou Kyriaki, Dhejne Cecilia, Bookheimer Susan, Savic Ivanka Female-to-Male Transsexual Individuals Demonstrate Different Own Body Identification Archives of sexual behavior, 2015; 229(1-2)
Transsexualism is characterized by feelings of incongruity between one's natal sex and one's gender identity. It is unclear whether transsexual individuals have a body image that is more congruent with their gender identity than their sex assigned at birth (natal sex) and, if so, whether there are contributions from perceptual dysfunctions. We compared 16 pre-hormone treatment female-to-male transsexual (FtM) individuals to 20 heterosexual female and 20 heterosexual male controls on a visual identification task. Participants viewed photographs of their own body that were morphed by different degrees to bodies of other females or males, and were instructed to rate "To what degree is this picture you?" We also tested global vs. local visual processing using the inverted faces task. FtM differed from both control groups in demonstrating higher self-identification ratings for bodies morphed to the sex congruent with their gender identity, and across a broad range of morph percentages. This difference was more pronounced for longer viewing durations. FtM showed reduced accuracy for upright faces compared with female controls for short duration stimuli, but no advantage for inverted faces. These results suggest different own body identification in FtM, consisting of a relatively diffuse identification with body images congruent with their gender identity. This is more likely accounted for by conscious, cognitive factors than perceptual differences.