Association of cerebral networks in resting state with sexual preference of homosexual men: a study of regional homogeneity and functional connectivity.

Shaohua Hu,Xiaofu He,Xiaojun Xu,Manli Huang,Yi Xu,Jianbo Hu,Dongrong Xu,Qidong Wang,Weijuan Xu,Minming Zhang,Bradley Peterson,Ning Wei,Weihua Zhou,Dan Long,Gaolang Gong

doi:10.1371/journal.pone.0059426

Abstract

Recent imaging studies have shown that brain morphology and neural activity during sexual arousal differ between homosexual and heterosexual men. However, functional differences in neural networks at the resting state is unknown. The study is to characterize the association of homosexual preference with measures of regional homogeneity and functional connectivity in the resting state. Participants were 26 healthy homosexual men and 26 age-matched healthy heterosexual men in whom we collected echo planar magnetic resonance imaging data in the resting state. The sexual orientation was evaluated using the Kinsey Scale. We first assessed group differences in regional homogeneity and then, taking the identified differences as seed regions, we compared groups in measures of functional connectivity from those seeds. The behavioral significances of the differences in regional homogeneity and functional connectivity were assessed by examining their associations with Kinsey Scores. Homosexual participants showed significantly reduced regional homogeneity in the left inferior occipital gyrus, right middle occipital gyrus, right superior occipital gyrus, left cuneus, right precuneus, and increased regional homogeneity in rectal gyrus, bilateral midbrain, and left temporal lobe. Regional homogeneity correlated positively with Kinsey scores in the left inferior occipital gyrus. The homosexual group also showed reduced functional connectivity between left middle temporal gyrus, left supra-marginal gyrus, right cuneus and the seed region, i.e. left inferior occipital gyrus. Additionly, the connection between the left inferior occipital gyrus and right thalamus correlated positively with Kinsey scores. These differences in regional homogeneity and functional connectivity may contribute to a better understanding of the neural basis of male sexual orientation.

Highlights

The neural basis of sexual orientation, which has been studied intensively for more than a century, has been hypothesized to relate to neuroendocrine influences [1], neurotransmitters [2], brain morphology [3,4,5], and genetic factors [6]
Ponseti and colleagues [15] suggested that sexual orientation could be assessed by hemodynamic brain response to visual sexual stimuli, one study showed no difference in the pattern of activation between homosexual and heterosexual participants who were viewing faces of romantic partners of either the opposite or the same gender [16]
The correlation of regional homogeneity (ReHo) at each voxel with scores on the Kinsey Scale in the homosexual group at resting state were significantly positive in left inferior occipital gyrus, left cerebellum, left precentral gyrus, and right postcentral gyrus, and significantly negative in left superior motor area and right superior parietal gyrus (P,0.05, corrected; Figure 3, Table 3)

Summary

Introduction

The neural basis of sexual orientation, which has been studied intensively for more than a century, has been hypothesized to relate to neuroendocrine influences [1], neurotransmitters [2], brain morphology [3,4,5], and genetic factors [6]. Paul et al [9] demonstrated that brain responses of heterosexual males to heterosexual stimuli is similar to that of homosexual males exposed to homosexual stimuli, suggesting a uniform neural response to the object of sexual desire that is independent of sexual orientation. They reported that despite equal ratings of sexual arousal, homosexual males and heterosexuasl women activated their hypothalamus less than did heterosexual men to visual erotic stimuli. Ponseti and colleagues [15] suggested that sexual orientation could be assessed by hemodynamic brain response to visual sexual stimuli, one study showed no difference in the pattern of activation between homosexual and heterosexual participants who were viewing faces of romantic partners of either the opposite or the same gender [16]

Methods

Results

Conclusion