Sex is in the brain, for women

The brain may play a key role in some 40 percent of women who experience sexual dysfunction with lack of sexual interest, researchers said.

Such women, ages 18-59, experience sexual dysfunction with lack of sexual interest called hypoactive sexual desire disorder, known as HSDD.

Bruce Arnow and Dr. Leah Millheiser of Stanford Hospital & Clinics said the trial involved 16 women diagnosed with HSDD, along with 20 normal control subjects, who took part in the study involving brain scans. All subjects identified themselves as heterosexual.

Subjects were shown erotic video segments interspersed among footage of female sporting events. The segments were separated by intervening tranquil sequences of such subjects as flowers, mountains or ocean waves to bring the women's brains to a resting state between more active segments.

The subjects' brain activity was monitored by functional magnetic-resonance imaging. The women also reported their subjective levels of sexual arousal throughout the viewing, while the researchers collected objective measurements of the women's level of genital arousal.

The findings, published in the journal Neuroscience, found activity patterns throughout most of the brain were more or less identical among the HSDD and normal groups, but with a few notable exceptions. There was a bigger jump in relative activity in three brain areas of HSDD women -- the medial frontal gyrus, right inferior frontal gyrus and bilateral putamen -- compared with the control subjects when shown the erotic clips.