New research has found that the part of the brain that governs fear and anxiety are shut off when a woman is having an orgasm. It does, however, remain active if she is fainting.

"The fact that there is no deactivation in faked orgasms means a basic part of a real orgasm is letting go. Women can imitate orgasm quite well, as we know, but there is nothing really happening in the brain," said Gert Holstege, neuroscientist.
In the study, Holstege and his colleagues at Groningen University recruited 11 men, 13 women, and their partners for the study.

Each volunteer was injected with a dye that shows changes in brain function on a scan. For the men, the scanner tracked their activity at rest, during erection, during manual stimulation by their partner, and also during ejaculation brought on by their partner's hand. For women, it measured brain activity at rest, while they faked an orgasm, while their partner stimulated their clitoris, and while they had an actual orgasm.

Although Holstege did have trouble getting true results from the men because their climaxes are short, women's results were more clear. When a woman faked an orgasm, the cortex lit up, but it remained inactive during a true orgasm.

However, the most striking results were seen in the parts of the brain that actually shut down, or deactivated."During orgasm, there was strong, enormous deactivation in the brain. During fake orgasm, there was no deactivation of the brain at all. None," said Holstege.