Free Phantoms in the Brain: Probing the Mysteries of the Human Mind by V. S. Ramachandran, Sandra Blakeslee Page B

phantom penis. Would such a patient find tap dancing especially enjoyable?
    What about mastectomy? An Italian neurologist, Dr. Salvatore Aglioti, recently found that a certain proportion of women with radical mastectomies experience vivid phantom breasts. So, he asked himself, what body parts are mapped next to the breast? By stimulating adjacent regions on the chest he found that parts of the sternum and clavicle, when touched, produce sensations in the phantom nipple. Moreover, this remapping occurred just two days after surgery.
    Aglioti also found to his surprise that one third of the women with radical mastectomies tested reported tingling, erotic sensations in their phantom nipples when their earlobes were stimulated. But this happened only in the phantom breast, not in the real one on the other side. He speculated that in one of the body maps (there are others besides the Penfield map) the nipple and ear are next to each other. This makes you wonder why many women report feeling erotic sensations when their ears are nibbled during sexual foreplay. Is it a coincidence, or does it have something to do with brain anatomy? (Even in the original Penfield map, the genital area of women is mapped right next to the nipples.)
    32

    A less titillating example of remapping also involving the ear came from Dr. A. T. Caccace, a neurologist who told me about an extraordinary phenomenon called gaze tinnitus.
    People with this condition have a weird problem. When they look to the left (or right), they hear a ringing sound. When they look straight ahead, nothing happens. Physicians have known about this syndrome for a long time but were stymied by it. Why does it happen when the eyes deviate? Why does it happen at all?
    After reading about Tom, Dr. Caccace was struck by the similarity between phantom limbs and gaze tinnitus, for he knew that his patients had suffered damage to the auditory nerve—the major conduit connecting the inner ear to the brain stem. Once in the brain stem the auditory nerve hooks up with the auditory nucleus, which is right next to another
    structure called the oculomotor nerve nucleus. This second, adjacent structure sends commands to the eyes, instructing them to move. Eureka! The mystery is solved.11 Because of the patient's damage, the auditory nucleus no longer gets input from one ear. Axons from the eye movement center in the cortex invade the auditory nucleus so that every time the person's brain sends a command to move the eyes, that command is sent inadvertently to the auditory nerve nucleus and translated into a ringing sound.
    The study of phantom limbs offers fascinating glimpses of the architecture of the brain, its astonishing capacity for growth and renewal12 and may even explain why playing footsie is so enjoyable. But about half the people with phantom limbs also experience the most unpleasant manifestation of the phenomenon—phantom limb pain. Real pain, such as the pain of cancer, is hard enough to treat; imagine the challenge of treating pain in a limb that isn't there! There is very little that can be done, at the moment, to alleviate such pain, but perhaps the remapping that we observed with Tom may help explain why it happens.
    We know, for instance, that intractable phantom pain may develop weeks or months after the limb is amputated. Perhaps as the brain adjusts and cells slowly make new connections, there is a slight error in the remapping so that some of the sensory input from touch receptors is accidentally connected to the pain areas of the brain. If this were to happen, then every time the patient smiled or accidentally brushed his cheek, the touch sensations would be experienced as excruciating pain. This is almost certainly not the whole explanation for phantom pain (as we shall see in the next chapter), but it's a good place to start.
    As Tom left my office one day, I couldn't resist asking him an obvious question. During the last four weeks, had he ever noticed any of these