The way in which the female genitals are represented in the cerebral cortex
is completely under-studied. A new study done by stimulating the clitoris of
20 women, while performing an fMRI of their brains, found that the
representation of their genitals was located near that of the hip. The
researchers also showed that the frequency of intercourse in the past 12
months was correlated with the structural thickness of the mapped field.
Our brain continuously receives sensory information from our body. The
somatosensory cortex is responsible for capturing and integrating them
through our neurons. Each part of the body corresponds to a specific region
of the somatosensory cortex, thus constituting a cerebral map of the human
body. In 2005, other researchers had developed a technique causing very
localized tactile stimulation of the penis, which allowed them to find the
precise region devoted to this area: near that of the hip. It is now the
turn of the clitoris - the female organ dedicated in particular to sexual
pleasure - to be an object of study.
Until now, the precise place dedicated to the female genitalia has been
controversial. Previous studies had placed it either under the
representation of the foot, or near that of the hip. But stimulation
techniques (by oneself or a partner) were imprecise since other parts of the
body were affected at the same time, or the process triggered arousal, which
blurred the results.
The new study, led by German researchers, involved stimulating the clitoris
of 20 women aged 18 to 45 while their brains were observed by functional
magnetic resonance imaging (fMRI). For the stimulation, a small round object
was applied above the underwear at the level of the clitoris: thanks to air
jets, a small membrane began to vibrate slightly. Eight stimuli of the
clitoris were performed - of 10 seconds each and interspersed with 10
seconds of rest. The same device was used on the back of the right hand as a
control.
The precisely activated area varies among women
The researchers specify that this study does not answer questions such as
whether having a larger area devoted to genital stimulation would allow
better perception of sensations. And does having a more developed sensory
zone encourage more sexual intercourse, or conversely, does frequent
intercourse make her grow as one works a muscle? So many questions still
unanswered.
The only certainty for researchers is that the place of the clitoris in the
somatosensory cortex is next to the hip (as with the penis). This
corresponds to Brodmann areas 1, 2 and 3a, located along the post-central
gyrus, but the precise location varies greatly between each woman tested.
Scientists then investigated whether this area exhibited different
characteristics depending on sexual activity. The 20 women were asked about
the frequency of their sexual intercourse over the past year, as well as since
the beginning of their sex life. Then, for each of them, the researchers
determined the ten points in the brain that were most activated during
stimulation, and they measured the thickness of these areas.
"We found an association between the frequency of intercourse and the
thickness of the individually mapped genital field," Christine Heim, co-author
of the report and professor of medical psychology at Charité University
Hospital in Berlin , told AFP. . Further studies may confirm the hypothesis
that the more intercourse, the larger the area.
But past research gives clues. First of all, it is well established that the
more we use certain parts of the brain, the more they grow: this is brain
plasticity. Second, previous animal studies have shown that stimulation of
the genitals of rats and mice actually causes the area of the brain
corresponding to the rats and mice to expand.
Towards therapy for people who have suffered sexual violence
In addition, these observations could help improve the care of women who
have suffered sexual violence, by acting directly on the areas of the brain
activated by the clitoris.
Heim had previously shown that people who had suffered traumatic sexual
violence had thinning of the areas of the brain devoted to the genitals. “We
speculated at the time that this might be the brain's response to curb the
damaging perception of abuse,” she said. She now hopes that her research
will lead to future therapies aimed at rehabilitating this region in abuse
survivors.
Reference:
Sensory-Tactile Functional Mapping and Use-Associated Structural Variation of
the Human Female Genital Representation Field, Journal of Neuroscience 20
December 2021, JN-RM-1081-21;
DOI: 10.1523/JNEUROSCI.1081-21.2021
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