Swedish scientists have suggested that brains of gay people may share similar physical attributes to those of the opposite sex.
Previous research has found differences between men and women in the extent to which they employ the brain’s hemispheres in verbal tasks, while other studies have suggested that gay people people may exhibit the tendencies of the opposite sex in brain behavior unrelated to sexual activity.
In this study, Ivanka Savic and Per Lindström, of the Department of Clinical Neuroscience at the Karolinska Institute in Stockholm, Sweden, say they believe the brains of heterosexual men and lesbians are slightly asymmetric, with the right hemisphere larger than the left.
However, the brains of gay men and straight women were found to be symmetrical.
The study, which analysed the brains of 90 subjects through MRI and PET scans, also found that in connectivity of the amygdala (which is used for emotional learning), lesbians resemble straight men, and gay men resemble straight women.
The authors suggested that one reason for the connectivity pattern in straight men and lesbians could be that the amygdala is wired for a greater fight-or-flight response.
Last year, another study found that the brains of gay men and women have structural and functional differences from those of their straight counterparts.
The Wellcome Trust Centre for neuro-imaging at University College London used MRI scans to look into the brains of 80 men and women, including 16 gays and 15 lesbians.
They found that lesbians have a "male-like" proportion and distribution of grey matter in their brain when compared with heterosexual women.