Adventures In Behavioral Neurology: What Neurology Can Tell Us About Human Nature

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So here is something staring you in the face, an extraordinary syndrome, utterly mysterious, where a person wants his normal limb removed. Why does this happen? There are all kinds of crazy theories about it including Freudian theories. One theory asserts, for example, that it’s an attention seeking behavior. This chap wants attention so he asks you to remove his arm. It doesn’t make any sense. Why does he not want his nose removed or ear removed or something less drastic? Why an arm? It seems a little bit too drastic for seeking attention.

[V.S. RAMACHANDRAN:] I’m interested in all aspects of the human mind, including aspects of the mind that have been regarded as ineffable or mysterious. The way I approach these problems is to look at patients who have sustained injury to a small region in the brain, a discipline called Behavioral Neurology or Cognitive Neuroscience these days.

Let me tell you about the problem confronting us. The brain is a 1.5 kilogram mass of jelly, the consistency of tofu, you can hold it in the palm of your hand, yet it can contemplate the vastness of space and time, the meaning of infinity and the meaning of existence. It can ask questions about who am I, where do I come from, questions about love and beauty, aesthetics, and art, and all these questions arising from this lump of jelly. It is truly the greatest of mysteries. The question is how does it come about?

 When you look at the structure of the brain it’s made up of neurons. Of course, everybody knows that these days. There are 100 billion of these nerve cells. Each of these cells makes about 1,000 to 10,000 contacts with other neurons. From this information people have calculated that the number of possible brain states, of permutations and combinations of brain activity, exceeds the number of elementary particles in the universe.

The question is how do you go about studying this organ? There are various ways of doing it. These days brain imaging is very popular. You make the person perform some task, engage in conversation or think about love, for that matter, or something like that, or imagine the color red. What part of the brain lights up? That gives you some confidence in saying that that region of the brain is involved in mediating that function. I’m sort of simplifying it, but something along those lines. Then there is recording from single cells where you put an electrode through the brain, eavesdrop on the activity of individual neurons, find out what the neuron is responsive to in the external world. There are dozens of such approaches, and our approach is behavioral neurology combined with brain imaging.

Behavioral neurology has a long history going back about 150 years, a venerable tradition going back to Charcot. Even Freud was a behavioral neurologist. We usually think of him as a psychologist, but he was also a neurologist. In fact, he began his career as a neurologist, comparable in stature with Charcot, Hughling Jackson, Kurt Goldstein. What they did was to look at patients with sustained injury to a very small region of the brain—and this is what we do as well in our lab. What you get is not a blunting of all your mental capacities or across the board reduction of your mental ability. What you get often is a highly selective loss of one specific function, other functions being preserved relatively intact. This gives you some confidence in saying that that region of the brain is specialized in dealing with that function.

It doesn’t have to be a lesion; it can be a genetic change. One of the phenomena that we’ve studied, for example, is synesthesia, the merging of the senses (which I’ll talk about in a minute) where’s there has been a genetic glitch. It runs in families in whom some gene or genes cause people to hear colors and taste sounds. They’ve got their senses muddled up. We’ve been studying this phenomenon.

In general, we look at is curious phenomenon, syndromes that have been known for ages, maybe 100 years, 50 years, that people have brushed under the carpet because they’re regarded as anomalies, to use Thomas Kuhn’s phrase. What do you make of somebody who says, “I see five as red, six as blue, seven as green, F sharp as indigo.” It doesn’t make any sense and when you see this in science, the tendency among most scientists, most of my colleagues at any rate, is to brush it under the carpet and pretend it doesn’t exist, deny it. What we do is to go and rescue these phenomena from oblivion, studying them intensively in the laboratory. Nine out of ten times it’s a wild goose chase, but every now and then you hit the jackpot and you discover something really interesting and important. This is what happened with synesthesia. Another example, which maybe I’ll begin with, is one most people have heard of, our work on phantom limbs and mirrors, which I’ll touch on in a minute.

One of the peculiar syndromes, which we have studied recently, is called apotemnophilia. It’s in fact so uncommon that many neurologists and many psychiatrists have not heard of it. It’s in a sense a converse of phantom limbs. In a phantom limb patient an arm is amputated but the patient continues to vividly feel the presence of that arm. We call it a phantom limb. In apotemnophilia you are dealing with a perfectly healthy, normal individual, not mentally disturbed in any way, not psychotic, not emotionally disturbed, often holding a job, and has a family.

We saw a patient recently who was a prominent dean of an engineering school and soon after he retired he came out and said he wants his left arm amputated above the elbow. Here’s a perfectly normal guy who has been living a normal life in society interacting with people. He’s never told anybody that he harbored this secret desire—intense desire—to have his arm amputated ever since early childhood, and he never came out and told people about it for fear that they might think he was crazy. He came to see us recently and we tried to figure out what was going on in his brain. And by the way, this disorder is not rare. There are websites devoted to it. About one-third of them go on to actually get it amputated. Not in this country because it’s not legal, but they go to Mexico or somewhere else and get it amputated.

So here is something staring you in the face, an extraordinary syndrome, utterly mysterious, where a person wants his normal limb removed. Why does this happen? There are all kinds of crazy theories about it including Freudian theories. One theory asserts, for example, that it’s an attention seeking behavior. This chap wants attention so he asks you to remove his arm. It doesn’t make any sense. Why does he not want his nose removed or ear removed or something less drastic? Why an arm? It seems a little bit too drastic for seeking attention.

The second thing that struck us is the guy would often take a felt pen and draw a very precise irregular line around his arm or leg and say, “I want it removed exactly that way. I don’t want you removing too little of it or too much of it. It would feel wrong. I want you to amputate it exactly on that line.” And you could test him after a year it is the same wiggly line which he couldn’t have memorized, and this suggests already that this is something physiological, and not something psychological that he is making up.

Another theory that is even more absurd (found in some papers, and again, it’s also a Freudian theory) is that the guy wants a big stump because it resembles a giant penis. Sort of wish fulfillment. This again is ridiculous, complete nonsense, of course. The question is why does it actually happen? What we were struck by was that there are certain syndromes where the patient has a right hemisphere stroke, in the right parietal cortex. The patient then starts denying that the left arm belongs to him. He says, “Doctor, this arm,” he’ll often point to it with his right arm and say, “this arm belongs to my mother.” Here’s a person who is perfectly coherent, intelligent, can discuss politics with you, can discuss mathematics with you, play chess with you, asserting that his left arm doesn’t belong to him.

This is different from apotemnophilia. In apotemnophilia the patient says, “This arm is mine, but I don’t want it. I want it removed.” But there are similarities, there’s an overlap, so we suggested that maybe there’s something wrong with his body image in the right hemisphere, which alienates the left arm, or the right arm, for that matter, from the rest of the person’s body and the sense of alienation leads to the person saying, “I don’t want it. Have it removed.”…

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