In response to the passing of Amendment One in North Carolina and President Obama's recent comments supporting same-sex marriage, I've included a short excerpt about sexual orientation and the brain from my book, Dirty Minds: How Our Brains Influence Love, Sex, and Relationships:
Is what I experience when I feel love qualitatively different from what a man experiences? Or what a lesbian may experience? If I consider Semir Zeki’s hypothesis that literature and art across the ages show a common substrate for love in the mind, I might suggest that descriptions of sex by male and female authors and artists are sometimes different. But descriptions of love by writers of both genders? They aren’t all that dissimilar. Nor are those written by gay authors.
Although previous neuroimaging studies of romantic love by Zeki and Fisher included members of both sexes, a precise comparison of brain activation between the two was not undertaken. Nor were comparisons of heterosexual and homosexual love. Zeki and his collaborator John Paul Romaya decided to take a closer look to determine whether there were differences in the way these different groups experience love.
They compared cerebral blood flow in twenty-four people in committed relationships who claimed to be passionately in love (and scored high enough on a passionate love questionnaire to back that claim). Twelve of those participants were men, and six of those men were gay. The remaining group of twelve women was also made up equally of gay and straight women. The study paradigm was identical to Zeki’s initial romantic love study: each participant’s brain was scanned as he or she passively viewed photos of his or her partner and a familiar acquaintance matched in gender and age to their true love.
Zeki and Romaya found similar patterns of brain activation and deactivation across all participants, replicating the findings from Zeki’s original romantic love study. Once again measurements of cerebral blood flow support the idea that love is both rewarding and blind. But there were no significant differences between activation patterns in men and women, nor between gay and straight individuals. Considering the sexual dimorphism seen in many parts of the brain, it’s an intriguing result. It appears that love is love, no matter what gender or sexual orientation you are.
When I asked Zeki if he was surprised by the finding, he chuckled. “To be honest, I was entirely agnostic,” he said. “I cannot say I was surprised by the results. But I think this is one of these studies where people would have said, ‘I’m not surprised,’ even if the results had gone the other way.”