Neural Correlates of Bisexuality in Women

Abstract

To date, research on the neurobiology of sexuality has focused on comparisons between heterosexual and lesbian women. Using structural MRI brain imaging techniques, research has identified significant differences in cortical thickness, subcortical volumes, and grey matter volume between heterosexual and lesbian women. However, research on brain differences as a function of sexual orientation in bisexual women is still limited. In this study, 16 bisexual women aged 25–50 years underwent T1 structural MRI scanning. We compared our sample to two control cohorts of 26 heterosexual women and 24 lesbian women provided by Dr. Adam Safron and Dr. Victoria Klimaj of Northwestern University in terms of cortical thickness, subcortical volume, and grey matter volume. When comparing bisexual women to lesbian women and bisexual women to heterosexual women, significant differences in cortical thickness and subcortical volume were found in multiple regions involved in visual, auditory, and emotion processing. These findings suggest the possibility of a relationship between sexual orientation and brain structure in bisexual, lesbian, and heterosexual women. Future research should investigate the functional applications of these structural differences, as well as whether structure or function is a better predictor of sexual orientation.