Most of a woman's brain shuts down when she has an orgasm, a team led by a Dutch neuroscientist has found by using brain scans.
"The main thing we saw in females is deactivation of the brain, which was unbelievable; really very pronounced," Gert Holstege from the University of Groningen in the north of the country said.
"What you see is deactivation of large parts of the brain, especially the emotional brain, the fear centres," he said.
His team recruited volunteer couples to engage in sexual activity while having undergoing a brain scan. Thirteen women and 11 men, aged 19 to 49, took part.
They found that the brains of volunteers who simulated orgasm after a period of stimulation remained fully active and in conscious control.
Mr Holstege found that the only part of the brain active during orgasm was the cerebellum, which is linked to the control of movement, although some experts believe it has a role in the emotion.
"If you look at the women who faked orgasm, we see the same kind of thing in the cerebellum taking place, but the cortex, the conscious part of the brain, is also active," he said.
"Women can imitate orgasm quite well, but in the brain it's not the same," he added.
Similar research on the men yielded unsatisfactory results, as the male orgasm is brief, lasting only about 20 seconds.
The scans showed that the cerebellum was active in men too.
Mr Holstege said he believed men's brains were also largely deactivated, but the results were inconclusive.
There were significant differences between men and women, however.
In men, the team found that a primitive part of the brain called the insula was activated.
And in women, the hippocampus, the memory part of the brain, was deactivated.
Mr Holstege presented his findings to the European Society of Human Reproduction and Embryology in Copenhagen.
Describing the circumstances of the experiment, he said the volunteers being scanned had to keep their heads still. They did not have intercourse but engaged in other forms of stimulation.
"We are neuroscientists, so we're only interested in the brain," he said.
He expressed the hope that the research could lead to treatment for sexual dysfunction.