Neuroaffective Processing of Sexually Relevant Images in Hetero- and Homosexual Women and Men: Subjective, Pupillometric, and Magnetoencephalographic Correlates.

Gender identity and sexual orientation form fundamental characteristics of an individual's sexual identity and relate to patterns of physiological and neural activity involved in processing erotic or explicit sexual stimuli. To investigate this, we used high-density magnetoencephalography (MEG) to measure brain responses of hetero- and homosexual women and men to opposite- and same-sex erotic images, as well as sexually explicit images. Additionally, we administered pupillometry and subjective measures of hedonic valence and emotional arousal. Erotic versus sexually explicit stimuli initially resulted in enhanced pupil dilation and stronger neural activity in the extended visual cortex, but at later times, reverse effects were found. Our results further showed that perceived affect varied by gender and sexual orientation, with significant group effects. Pupil measurements revealed differences in dilation depending on opposite- and same-sex erotic and sexually explicit images and participant groups. Similarly, effects of stimuli content were found for the neural activity. The findings suggest that preferred versus non-preferred stimuli are subjectively processed in a category-specific way, especially in hetero- and homosexual males as well as homosexual women compared to heterosexual women, and indicate a sensitivity to sexual images in affective-motivational and reward areas of the brain. To conclude, subjective, visual, and neural responses to sexually relevant stimuli seem partly dependent on gender and sexual orientation but predominanly indicate influences of stimulus content.