Вилейанур Рамачандран - Phantoms in the Brain

One day I got a call from a young woman in Boston. “Dr. Ramachandran”, she said, “I’m a graduate student at Beth Israel Hospital and for several years I’ve been studying Parkinson’s disease. But recently I decided to switch to the study of phantom limbs.”

“Wonderful”, I said. “The subject has been ignored far too long. Tell me what you are studying.”

“Last year I had a terrible accident on my uncle’s farm. I lost my left leg below the knee and I’ve had a phantom limb ever since. But I’m calling to thank you because your article made me understand what is going on.” She cleared her throat. “Something really strange happened to me after the amputation that didn’t make sense. Every time I have sex I experience these strange sensations in my phantom foot. I didn’t dare tell anybody because it’s so weird. But when I saw your diagrams, that in the brain the foot is next to the genitals, it became instantly clear to me.”

She had experienced and understood, as few of us ever will, the remapping phenomenon. Recall that in the Penfield map the foot is beside the genitals. Therefore, if a person loses a leg and is then stimulated in the genitals, she will experience sensations in the phantom leg. This is what you’d expect if input from the genital area were to invade the territory vacated by the foot.

The next day the phone rang again. This time it was an engineer from Arkansas.

“Is this Dr. Ramachandran?”

“Yes.”

“You know, I read about your work in the newspaper, and it’s really exciting. I lost my leg below the knee about two months ago but there’s still something I don’t understand. I’d like your advice.”

“What’s that?”

“Well, I feel a little embarrassed to tell you this.”

I knew what he was going to say, but unlike the graduate student, he didn’t know about the Penfield map.

“Doctor, every time I have sexual intercourse, I experience sensations in my phantom foot. How do you explain that? My doctor said it doesn’t make sense.”

“Look”, I said. “One possibility is that the genitals are right next to the foot in the body’s brain maps. Don’t worry about it.”

He laughed nervously. “All that’s fine, doctor. But you still don’t understand. You see, I actually experience my orgasm in my foot. And therefore it’s much bigger than it used to be because it’s no longer just confined to my genitals.”

Patients don’t make up such stories. Ninety-nine percent of the time they’re telling the truth, and if it seems incomprehensible, it’s usually because we are not smart enough to figure out what’s going on in their brains.

This gentleman was telling me that he sometimes enjoyed sex more after his amputation. The curious implication is that it’s not just the tactile sensation that transferred to his phantom but the erotic sensations of sexual pleasure as well. (A colleague suggested I title this book “The Man Who Mistook His Foot for a Penis”.)

This makes me wonder about the basis of foot fetishes in normal people, a subject that — although not exactly central to our mental life — everyone is curious about. (Madonna’s book, Sex , has a whole chapter devoted to the foot.) The traditional explanation for foot fetishes comes, not surprisingly, from Freud. The penis resembles the foot, he argues, hence the fetish. But if that’s the case, why not some other elongated body part?

Why not a hand fetish or a nose fetish? I suggest that the reason is quite simply that in the brain the foot lies right next to the genitalia. Maybe even many of us so-called normal people have a bit of cross-wiring, which would explain why we like to have our toes sucked. The journeys of science are often tortuous with many unexpected twists and turns, but I never suspected that I would begin seeking an explanation for phantom limbs and end up explaining foot fetishes as well.

Given these assumptions, other predictions follow. 10 What happens when the penis is amputated? Carcinoma of the penis is sometimes treated with amputation, and many of these patients experience a phantom penis — sometimes even phantom erections! In such cases you would expect that stimulation of the feet would be felt in the 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.)

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 renewal 12 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.