New reseach shows that female orgasm appears to shut down the centers of the brain that allow women to feel fear and emotion. From "New Scientist:"
“At the moment of orgasm, women do not have any emotional feelings,” says Gert Holstege of the University of Groningen in the Netherlands....As the women were stimulated, activity rose in one sensory part of the brain, called the primary somatosensory cortex, but fell in the amygdala and hippocampus, areas involved in alertness and anxiety. During orgasm, activity fell in many more areas of the brain, including the prefrontal cortex, compared with the resting state..."
In one sense the findings appear to confirm what is already known, that women cannot enjoy sex unless they are relaxed and free from worries and distractions. "Fear and anxiety levels have to go down for orgasm. Everyone knows this but we can see it happening in the brain," (Holstege) explains.
From an evolutionary point of view, it could be that the brain switches off the emotions during sex because at such times the chance to produce offspring becomes more important than the survival risk to the individual. Holstege points to the extraordinary behaviour seen in some animals during the breeding season, such as March hares, when the urge to mate seems to override the usual fear of predators. Link
On the downside, researchers were able to tell when women were faking by seeing which parts of the brain were active during orgasm. (Thanks to Wendee Higa Lee for this link.)
When women genuinely achieved an orgasm, areas of the brain involved in fear and emotion were deactivated. Those areas stayed alert however when women were faking it.
The researchers also found that the cortex, which is linked with consciousness, is active during a fake orgasm but not during the real thing.
"The deactivation of these very important parts of the brain might be the most important thing necessary to have an orgasm," said Holstege.
"It means that if you are fearful or at a very high level of anxiety, then it is very difficult to have sex because you really have to let yourself go," he added.
The brain scans for men during orgasm were less conclusive, according to Holstege.
But they did show that different parts of the male and female brain are activated and deactivated during sexual stimulation.
The researchers found less deactivation in the males in the areas of the brain linked to emotion and fear when they were sexually stimulated.
They are now planning further studies to compared the male and female brains during orgasm.