Anatomical and Functional Findings in Female-to-Male Transsexuals: Testing a New Hypothesis

Manzouri, Amirhossein; Kosidou, Kyriaki; Savić, Ivanka

doi:10.1093/cercor/bhv278

Cited by 58 publications

(125 citation statements)

References 64 publications

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“…This accords with our structural MRI studies of GD (Manzouri et al 2015; Savic and Arver 2011), as well as studies of white matter microstructure (Kranz et al 2014), graph theoretical network analyses of white matter connectivity (Hahn et al 2015), and resting state functional connectivity (Lin et al 2014), all of which also suggest that GD may be associated with its own, singular features. In the latter resting state fMRI study, MtF and FtM as a group, compared with controls, demonstrated greater degree connectivity of the postcentral gyrus and superior parietal lobule (“body representation areas”) within a whole brain network, and greater connectivity of these nodes with sensorimotor network nodes.…”

Section: Discussionsupporting

confidence: 87%

“…Indeed, our recent study of cortical thickness in a (partially overlapping)sample of GD individuals demonstrated significantly thicker cortex in the ACC, mPFC, precuneus, cuneus, left inferior parietal, and temporal cortex in FtM than both male and female controls (Manzouri et al 2015). In the absence of longitudinal data it is, however, not feasible to disentangle between the two alternatives, which, in addition, are not necessarily mutually exclusive.…”

Section: Discussionmentioning

confidence: 93%

“…However, we recently found that cortical thickness is increased in GD compared with both male and female controls, specifically along the midline axis (pACC, the superior, rostral, and middle frontal gyri – including portions of the orbitofrontal gyrus), in occipital regions (right lingual gyrus, pericalcarine cortex, and cuneus), and in the right inferior temporal gyrus (Manzouri et al 2015). This raises the question whether the functional connectivity within the DMN (which includes pACC), and/or other networks involved in self- and own-body awareness (SN) and perception (visual networks) could differ in GD from controls, and if distinct patterns of connectivity could be related to perception of own body perception in the context of self.…”

Section: Introductionmentioning

confidence: 96%

“…We hypothesized that connectivity within the DMN would be abnormal in FtM, given the finding of greater Cth in the pACC (Manzouri et al 2015). Further, we predicted connectivity in this network would be weaker in FtM than in both control groups, following a model of lesser integration of own-body representation of physical traits of their gender assigned at birth (posterior division of DMN) and their consciously accessible, “psychological” self-representation (anterior division of DMN, as shown in (Salomon et al 2014)).…”

Section: Introductionmentioning

confidence: 99%

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Intrinsic network connectivity and own body perception in gender dysphoria

Feusner

Lidström

Moody

et al. 2016

Brain Imaging and Behavior

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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.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Intrinsic network connectivity and own body perception in gender dysphoria

Feusner

Lidström

Moody

et al. 2016

Brain Imaging and Behavior

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“…These results suggest a heightened focus on sensory input in body representation. Manzouri, Kosidou, and Savic (2015) showed differences in the “own-body image network” and suggested that FtM individuals may have weaker connections between body perception networks and body self-ownership networks. They also reported reduced functional connectivity between the amygdala and the right precuneus and temporo-parietal junction, right extrastriate body area, and the fusiform cortex that might reflect greater separation of body perception and body-related emotion.…”

Section: Introductionmentioning

confidence: 99%

Altered White Matter and Sensory Response to Bodily Sensation in Female-to-Male Transgender Individuals

et al. 2016

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While most people take identification with their body for granted, conditions like phantom limb pain, alien hand syndrome, and xenomelia suggest that the feeling of bodily congruence is constructed and susceptible to alteration. Individuals with xenomelia typically experience one of their limbs as over-present and aversive, leading to a desire to amputate the limb. Similarly, many transgender individuals describe their untreated sexed body parts as incongruent and aversive, and many experience phantom body parts of the sex they identify with (Ramachandran, 2008). This experience may relate to differences in brain representation of the sexed body part, as suggested in xenomelia (McGeoch et al., 2011). We utilized magnetoencephalography imaging to record brain activity during somatosensory stimulation of the breast – a body part that feels incongruent to most pre-surgical female-to-male (FtM) identified transgender individuals – and the hand, a body part that feels congruent. We measured the sensory evoked response in right hemisphere somatosensory and body-related brain areas and found significantly reduced activation in the supramarginal gyrus and secondary somatosensory cortex but increased activation at the temporal pole for chest sensation in the FtM group (N = 8) relative to non-transgender females (N = 8). In addition, we found increased white matter coherence in the supramarginal gyrus and temporal pole and decreased white matter diffusivity in the anterior insula and temporal pole in the FtM group. These findings suggest that dysphoria related to gender-incongruent body parts in FtM individuals may be tied to differences in neural representation of the body and altered white matter connectivity.

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Role of testosterone and Y chromosome genes for the masculinization of the human brain

Savić

Frisén

Manzouri

et al. 2017

Human Brain Mapping

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Altogether, these data suggest that testosterone modulates the microstructure of somatosensory and visual cortices and their axonal connections to the frontal cortex. Testosterone also influenced functional connections from the amygdala, whereas the motor cortex could, in agreement with our previous reports, be moderated by processes linked to X-chromosome gene dosage. These data raise the question about other genetic factors masculinizing the human brain than the SRY gene and testosterone. Hum Brain Mapp 38:1801-1814, 2017. © 2017 Wiley Periodicals, Inc.

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Anatomical and Functional Findings in Female-to-Male Transsexuals: Testing a New Hypothesis

Cited by 58 publications

References 64 publications

Intrinsic network connectivity and own body perception in gender dysphoria

Intrinsic network connectivity and own body perception in gender dysphoria

Altered White Matter and Sensory Response to Bodily Sensation in Female-to-Male Transgender Individuals

Role of testosterone and Y chromosome genes for the masculinization of the human brain

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