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AJNR - American Journal of Neuroradiology

Published ahead of print on September 3, 2008
doi: 10.3174/ajnr.A1260

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American Journal of Neuroradiology 29:1890-1896, November-December 2008
© 2008 American Society of Neuroradiology

FUNCTIONAL

Patterns of Brain Activation during Visually Evoked Sexual Arousal Differ between Homosexual and Heterosexual Men

S.-h. Hu^a, N. Wei^a, Q.-D. Wang^b, L.-q. Yan^c, E.-Q. Wei^d, M.-M. Zhang^b, J.-B. Hu^a, M.-l. Huang^a, W.-h. Zhou^a and Y. Xu^a

^a Department of Mental Health, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
^b Department of Radiology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
^c MD Anderson Cancer Center, Virginia Harris Cockrell Cancer Research Center, University of Texas, Austin, Tex
^d Department of Pharmacology, College of Medicine, Zhejiang University, Hangzhou, China

Please address correspondence to Yi Xu, MD, Department of Mental Health, the First Affiliated Hospital, College of Medicine, Zhejiang University, 79 Qing Chun Rd, Hangzhou 310003, China; e-mail: xuyi1961{at}yahoo.com.cn

BACKGROUND AND PURPOSE: Nowadays the mechanism of homosexuality is little known. Few studies have been carried out to explore the brain functional changes of homosexual men during sexual arousal. We used functional MR imaging (fMRI) to determine whether the patterns of brain activation in homosexual and heterosexual men differed during visually evoked sexual arousal.

MATERIALS AND METHODS: To all the subjects (10 homosexual and 10 heterosexual), real-time visual stimulation was provided by 3-minute exposure to 3 types of erotic film: heterosexual couples (F-M), male homosexual couples (M-M), and female homosexual couples (F-F) engaged in sexual activity, during which time fMRI was used to determine the patterns of brain activation. Self-reports of level of sexual arousal were collected immediately afterward.

RESULTS: Statistical parametric mapping showed that viewing erotic film excerpts that induced sexual arousal was associated, in both groups, with activation of the middle prefrontal gyrus, bilateral temporal lobe and postcentral gyrus, thalamus, insula, vermis, left precuneus, occipital cortex, parietal cortex, and cerebellum. In homosexual men, the left angular gyrus, left caudate nucleus, and right pallidum were activated; in contrast, heterosexual men showed no activation in these regions. However, heterosexual men showed activation in the bilateral lingual gyrus, right hippocampus, and right parahippocampal gyrus, areas not activated in homosexual men. In both groups, region-of-interest analysis revealed no correlation between the magnitude of amygdala or thalamus activation and the reported level of sexual arousal.

CONCLUSION: Our findings indicate that different neural circuits are active during sexual arousal in homosexual and heterosexual men and may contribute to a better understanding of the neural basis of male sexual orientation.