Brain Biology and Sex

The stimuli that induce sexual arousal between men and women differ. Men are far more sexually aroused by visual erotic stimuli than are women. Functional MRI studies were conducted on twenty men and twenty women to compare their sexual arousal while they were viewing excerpts from neutral films and from erotic films. The level of sexual arousal was much higher in the males during the viewing of the erotic films. In both males and females the erotic films induced increased activation of several parts of the brain, most particularly the anterior cingulate, medial prefrontal, insular, occipitotemporal and orbitofrontal cortices, along with the amygdala and ventral striatum. But something additional happened in the male brains. Activation occurred in both the thalamus and the hypothalamus, but in the latter it was much more intense. The hypothalamus is known to have a critical role in sexual behavior and physiological arousal. The researchers found that in males the intensity of sexual arousal was positively correlated with the degree of activation of the hypothalamus. This study was confirmed by other studies that showed that sexual arousal from erotic film excerpts was associated with increased activity in the right amygdala, right anterior temporal pole, and the hypothalamus. The right superior frontal gyrus and right anterior cingulate gyrus were activated by attempts to inhibit the sexual arousal from the erotic films. The researchers concluded that humans implement self-regulation through a neural circuit involving some prefrontal regions and limbic structures. Studies have also shown the relationship between brain activation of specific areas and sexual response. One such study involved exposing healthy young heterosexual males to two sequences of video material.