The first brain scans of men and women having sex and reaching orgasm have
revealed striking differences in the way each experiences sexual pleasure.
While male brains focus heavily on the physical stimulation involved in
sexual contact, this is just one part of a much more complex picture for
women, scientists in the Netherlands have found.
The key to female arousal seems rather to be deep relaxation and a lack of
anxiety, with direct sensory input from the genitals playing a less critical
role.
The scans show that during sexual activity, the parts of the female brain
responsible for processing fear, anxiety and emotion start to relax and
reduce in activity. This reaches a peak at orgasm, when the female brain’s
emotion centres are effectively closed down to produce an almost trance-like
state.
The male brain was harder to study during orgasm, because of its shorter
duration in men, but the scans nonetheless revealed important differences.
Emotion centres were deactivated, though apparently less intensely than in
women, and men also appear to concentrate more on the sensations transmitted
from the genitals to the brain.
This suggests that for men, the physical aspects of sex play a much more
significant part in arousal than they do for women, for whom ambience, mood
and relaxation are at least as important.
"Men find it more important to be stimulated on the penis than women find
it to be stimulated on the clitoris," Gert Holstege of the University
of Groningen told the European Society of Human Reproduction and Embryology
conference in Copenhagen today. "We know from these images that each
sex experiences stimulation differently."
The experiments also revealed a rather surprising effect: both men and women
found it easier to have an orgasm when they kept their socks on. Draughts in
the scanning room left couples complaining of "literally cold feet",
and providing a pair of socks allowed 80 per cent rather than 50 per cent to
reach a climax while their brains were scanned.
The scans also show that while women may be able to fool their partners with a
fake orgasm, the difference is obvious in the brain. Parts of the brain that
handle conscious movement light up during fake orgasms but not during real
ones, while emotion centres close down during the real thing but never when
a woman is pretending.
In the study, a team at the University of Groningen led by Gert Holstege
scanned the brains of 13 women and 11 men using a technique called positron
emission tomography (PET), while they manually stimulated to orgasm by their
partners. All were heterosexual and right-handed, the latter to ensure that
all their brains could be easily compared.
The subjects’ heads were restrained in the PET scanner during the procedure,
as it only works if the body area being scanned remains still. The
dimensions of the scanner and the need for stillness also explain why the
researchers were unable to study intercourse itself.
In both sexes, activity in the amygdala, which processes fear and anxiety, was
reduced during stimulation. Women, but not men, showed lower activity in the
hippocampus, important for memory, as well.
In men, greater activity was seen in the insula, which deals with emotion, and
particularly in the secondary somatosensory cortex, which rates the
significance of physical sensations. This suggests that the sensory input
coming from the genitals is being judged highly important and pleasurable by
the brain.
Women, however, show very little increased brain activity, and only in the
primary somatosensory cortex - which registers purely that a sensation in
the genitals is there."In women the primary feeling is there, but not
the marker that this is seen as a big deal," Dr Holstege said."For
males, touch itself is all-important. For females, it is not so important."
As orgasm lasts much longer in women than in men, it is easier to study using
PET - male ejaculation is over so quickly it is hard to get a reliable
reading. The scans showed that in the female orgasm, activity is reduced
across all the brain regions - conscious and subconscious - that handle
emotion, including the amygdale, medial prefrontal cortex and orbitofrontal
cortex.
"What this means is that deactivation, letting go of all fear and
anxiety, might be the most important thing, even necessary, to have an
orgasm," Dr Holstege said.
