Guys, imagine for a moment what life would be like if you couldn't feel your penis. That can happen to men with some kinds of spinal injuries, or who were born with a condition called spina bifida. Their penis can still sense touch, but a break in the spinal cord means the signal never makes it to the brain.
There's now a surgery — the TOMAX procedure — that treats the problem: it involves rerouting a nerve that normally carries sensory information from one half of the glans by attaching it to the nerve that collects sensory information from the skin that covers the groin. After the surgery, touching the glans sends a sensory signal all the way up to the brain.
But because of the way brains make sense of where a touch comes from, patients initially interpret that sensation as a touch to the scrotum or inner thighs — the place where the nerve originally collected signals.
But over the course of about a year, patients begin to feel their penis as their penis, and the sensation goes from tickly to distinctly erotic. An fMRI study now available in the Journal of Sexual Medicine suggests that this shift happens inside the brain.
At least in these three patients, the brain didn't change where the nerve impulses landed when they first arrived: touching their glans still turned on the same region of the brain that once said "groin skin." But those new glans signals also turned on other parts of the brain, including several regions that differed from those stroking the scrotum, which may reflect how these patients have started to reinterpret the meaning of that touch.