I’ve just started reading V. S. Ramachandran’s “The Tell-Tale Brain.” Ramachandran is probably best known as the guy who figured out that you could treat phantom pain in amputees by rigging up a mirror system which made it look like their phantom limb was still part of their body. In the book he notes another interesting symptom of amputees. A person may lose their hand but still be able to feel hand sensation on parts of their face. Ramachandran explains this by noting that the somatosensory cortex in the brain — a strip of gray matter which perceives the sensation coming in from nerves in all parts of your body — groups neurons for the hand right next to neurons for the face. When these hand neurons are no longer being stimulated (because the hand is gone) they start to build connections to the neurons right next to them, the face neurons. The result is that the wires get crossed, so to speak, between the two parts of the body (one which doesn’t even exist.)
And this doesn’t just work for hands.
Finally, after amputation of the foot of another patient, sensations from the penis were felt in the phantom foot. (Indeed, the patient claimed that his orgasm spread into his foot and was therefore “much bigger than it used to be.”) This occurs because of another of these odd discontinuities in the brains map of the body: the map of the genitals is right next to the map of the foot.
It seems this could lead to a very misleading sensation for the patient: the notion that his penis is the size of his foot. It would therefore not be unexpected that he might approach women, pull out his foot sized (in his mind) penis and say something like, “how’d you like a piece of this?” I know this is something I would be tempted to do were I suffering from this illusion.
It does seem clear, however, that the most immediate task facing neuroscience is allowing us to have orgasms mapped over our entire bodies. (This is not unheard of. Many of the women I’ve slept with claimed I was able to achieve this function with them.)