Patterns of Brain Activation during Visually Evoked Sexual Arousal Differ

4: AJNR Am J Neuroradiol. 2008 Sep 3; [Epub ahead of print]

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

Hu SH, Wei N, Wang QD, Yan LQ, Wei EQ, Zhang MM, Hu JB, Huang ML, Zhou WH, Xu Y.
Departments of Mental Health and Radiology, First Affiliated Hospital, College
of Medicine, Zhejiang University, Hangzhou, China; MD Anderson Cancer Center,
Virginia Harris Cockrell Cancer Research Center, University of Texas, Austin,
Tex; and Department of Pharmacology, College of Medicine, Zhejiang University,
Hangzhou, China.

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.

PMID: 18768725 [PubMed - as supplied by publisher]