The Tell-Tale Brain: Nipple Stimulation is Sexy Thinking

Human Brain
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Remember those arcade machines from way back when where you would squeeze a pair of handles while watching a meter that would indicate your level of sexuality with labels such as “Too hot to handle,” “ Hot lips,” “Warm fuzzy,” “ Tepid,” “Frigid,” and “Corpse.” Fortunately, science has improved some since then technology-wise. However, we are still asking the same question: What is sexually stimulating and why? Today, we may be a little closer to the answer with a recent report in the July issue of The Journal of Sexual Medicine where scientists at Rutgers University discovered that there is an observable neurophysiological basis for the claim that stimulating the nipples can evoke sexual feelings in a woman’s brain.

Sensory homunculus: how our brain sees us

For anyone who has had freshman psychology 101, one of the more bizarre illustrations in their psychology textbook was that of a sensory homunculus. In Latin, homunculus means “little man.” In the textbook, the sensory homunculus appears as a grossly disfigured cartoon male wrapped over a supersized brain. The figure is a representation of the areas of the brain that when stimulated send signals to specific regions of the body. The deformed features represent a rough approximation of how much brain processing is devoted toward that body part relative to the other parts. For example, the tongue, lips and hands appear greatly exaggerated in comparison to the torso, legs and feet.

This illustration was derived from early studies when brain surgery patients (while conscious) were asked to describe what part of their body felt a sensation as a surgeon stimulated differing regions of their brain. Today, a more accurate sensory homunculus map of the brain can be made using functional magnetic resonance imaging.

fMRI: How we see our brain
Functional magnetic resonance imaging (fMRI) is a specialized type of neuroimaging that allows scientists to capture images of increased blood flow due to neuronal activity in specific regions of the brain. In the Rutgers’s study, 11 female test subjects ranging between 22 and 56 years of age tapped their clitoris and nipples with their fingers and stimulated their vaginas and cervixes with a plastic dildo while their brains were scanned with an fMRI.

Previous studies with men showed that genital stimulation led to increased neural activity in the medial paracentral lobule located on the top of the brain between the two hemispheres. With the female test subjects, the results of direct genital stimulation were as expected with increased neuronal activity observed in the same region of their brains as with men. However, what was not expected was a neuronal response in the same region as the genitals when the subjects stimulated their nipples.

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It wasn’t that the scientists did not expect to find neuronal activity with nipple stimulation, but it was a matter of where the neuronal activity was detected in the brain. Genitals lie within the nether regions of the human body, but the nipples are relatively physiologically distant. Nipple stimulation was expected to reveal itself only in the same region of the brain as where chest stimulation does as discovered in earlier studies. It appears as if nipples have sex nerves of their own.

Nerves of Sex
Four nerves pass signals from the genitals to the brain. The pudendal, pelvic and vagus nerves are connected to the clitoris, vagina and cervix respectively. The hypogastric nerve is connected to both the cervix and the uterus. The question the scientists are asking themselves now is whether or not nerves from the nipples are linked directly to the brain.

Another possibility is that the increased neuronal activity from nipple stimulation is indirect. Breast feeding is known to act as a hormonal trigger where oxytocin is released during nipple stimulation. The oxytocin elicits a contraction response from the uterus, which then signals the brain. A future study to answer this question will take a look at women who have had a hysterectomy to see if a brain/genital locus nipple stimulation response appears in their fMRI.

Future Sex

Dr. Barry Komisaruk, a psychologist at Rutgers University and one of the researchers in the study believes that their research may one day help women who have difficulty in achieving an orgasm due to physiological damage from childbirth or disease. However, another interest of his is to see whether or not we are capable of tapping into specific areas of our brain not unlike telling ourselves to wiggle our toes and doing so. If this is possible, we may see a day when we will learn how to overcome pain and discomfort by mentally concentrating on specific regions of our brain and eliciting a palliative effect.

Until then, however, I’m betting the first commercial use of this research will be a bed with a built-in fMRI so that a guy will be able to tell if she is really faking it or not.

Sources
Komisaruk, B. R., et.al. (2011), Women's Clitoris, Vagina, and Cervix Mapped on the Sensory Cortex: fMRI Evidence. The Journal of Sexual Medicine. doi: 10.1111/j.1743-6109.2011.02388.x
Barry R. Komisaruk: http://psychology.rutgers.edu/~brk/
Image source of Human Brain: Wikipedia

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