Sexual orientation and spatial position effects on selective forms of object location memory

Accurate machine learning prediction of sexual orientation based on brain morphology and intrinsic functional connectivity

BACKGROUND

Sexual orientation in humans represents a multilevel construct that is grounded in both neurobiological and environmental factors.

OBJECTIVE

Here, we bring to bear a machine learning approach to predict sexual orientation from gray matter volumes (GMVs) or resting-state functional connectivity (RSFC) in a cohort of 45 heterosexual and 41 homosexual participants.

METHODS

In both brain assessments, we used penalized logistic regression models and nonparametric permutation.

RESULTS

We found an average accuracy of 62% (±6.72) for predicting sexual orientation based on GMV and an average predictive accuracy of 92% (±9.89) using RSFC. Regions in the precentral gyrus, precuneus and the prefrontal cortex were significantly informative for distinguishing heterosexual from homosexual participants in both the GMV and RSFC settings.

CONCLUSIONS

These results indicate that, aside from self-reports, RSFC offers neurobiological information valuable for highly accurate prediction of sexual orientation. We demonstrate for the first time that sexual orientation is reflected in specific patterns of RSFC, which enable personalized, brain-based predictions of this highly complex human trait. While these results are preliminary, our neurobiologically based prediction framework illustrates the great value and potential of RSFC for revealing biologically meaningful and generalizable predictive patterns in the human brain.

Sexual Orientation and Cognitive Ability: A Multivariate Meta-Analytic Follow-Up

A cross-sex shift model of human sexual orientation differences predicts that homosexual men should perform or score in the direction of heterosexual women, and homosexual women in the direction of heterosexual men, in behavioral domains such as cognition and personality. In order to test whether homosexual men and women's cognitive performance was closer to that of heterosexual men or that of heterosexual women (i.e., sex-atypical for their sex and closer to that of the opposite-sex), we conducted a multivariate meta-analysis based on data from our previous meta-analysis (Xu, Norton, & Rahman, 2017). A subset of this data was used and comprised 30 articles (and 2 unpublished datasets) and 244,434 participants. The multivariate meta-analysis revealed that homosexual men were sex-atypical in mental rotation (Hedges' g = -0.36) and the water level test (Hedges' g = -0.55). In mental rotation, homosexual men were in-between heterosexual men and women. There was no significant group difference on spatial location memory. Homosexual men were also sex-atypical on male-favoring spatial-related tasks (Hedges' g = -0.54), and female-favoring spatial-related tasks (Hedges' g = 0.38). Homosexual women tended to be sex-typical (similar to heterosexual women). There were no significant group differences on male-favoring "other" tasks or female-favoring verbal-related tasks. Heterosexual men and women differed significantly on female-favoring "other" tasks. These results support the cross-sex shift hypothesis which predicts that homosexual men perform in the direction of heterosexual women in sex differentiated cognitive domains. However, the type of task and cognitive domain tested is critical.

Possible Neurobiological Underpinnings of Homosexuality and Gender Dysphoria

Although frequently discussed in terms of sex dimorphism, the neurobiology of sexual orientation and identity is unknown. We report multimodal magnetic resonance imaging data, including cortical thickness (Cth), subcortical volumes, and resting state functional magnetic resonance imaging, from 27 transgender women (TrW), 40 transgender men (TrM), and 80 heterosexual (40 men) and 60 homosexual cisgender controls (30 men). These data show that whereas homosexuality is linked to cerebral sex dimorphism, gender dysphoria primarily involves cerebral networks mediating self-body perception. Among the homosexual cisgender controls, weaker sex dimorphism was found in white matter connections and a partly reversed sex dimorphism in Cth. Similar patterns were detected in transgender persons compared with heterosexual cisgender controls, but the significant clusters disappeared when adding homosexual controls, and correcting for sexual orientation. Instead, both TrW and TrM displayed singular features, showing greater Cth as well as weaker structural and functional connections in the anterior cingulate-precuneus and right occipito-parietal cortex, regions known to process own body perception in the context of self.