The Tell-Tale Brain

having schizophrenia or “schizoid traits” (in addition to his epilepsy) and prescribed him antipsychotic medication. The last time I saw Ali, in 2009, he was claiming that in addition to being dead he had grown to enormous size, reaching out into the cosmos to touch the moon, becoming one with the Universe—as if nonexistence and union with the cosmos were synonymous. I began to wonder if his seizure activity had spread into his right parietal lobe, where body image is constructed, which might explain why he had lost his sense of scale, but I have not yet had a chance to investigate this hunch.

15. One might expect, therefore, that in Cotard syndrome there would initially be no GSR whatsoever, but it should be partially restored with SSRIs (selective serotonin reuptake inhibitors). This can be tested experimentally.

16. When I make remarks of this nature about God (or use the word “delusion”), I do not wish to imply that God doesn’t exist; the fact that some patients develop such delusions doesn’t disprove God—certainly not the abstract God of Spinoza or Shankara. Science has to remain silent on such maters. I would argue, like Erwin Schrodinger and Stephen Jay Gould, that science and religion (in the nondoctrinaire philosophical sense) belong to different realms of discourse and one cannot negate the other. My own view, for what it is worth, is best exemplified by the poetry of the bronze Nataraja (The Dancing Shiva), which I described in Chapter 8.

17. There has long been a tension in biology between those who advocate a purely functional, or black-box approach, and those who champion reductionism, or understanding how component parts interact to generate complex functions. The two groups are often contemptuous of each other.

     Psychologists often promote black-box functionalism and attack reductionist neuroscience—a syndrome I have dubbed “neuron envy.” The syndrome is partly a legitimate reaction to the fact that most funding from grant-giving agencies tends to be siphoned off, unfairly, by neuroreductionists. Neuroscience also garners the lion’s share of attention from the popular press, partly because people (including scientists) like looking at the results of brain imaging; all those pretty colored dots on pictures of brains. At a recent meeting of the Society for Neuroscience, a colleague approached me to describe an elaborate-brain imaging experiment he had done which used a complex cognitive- perceptual task to explore brain mechanisms. “You will never guess which area of the brain lit up, Dr. Ramachandran,” he said, brimming with enthusiasm. I responded with a sly wink saying, “Was it the anterior cingulate?” The man was astonished, failing to realize that the anterior cingulate lights up on so many of these tasks that the odds were already stacked in my favor, even though I was just guessing.

     But by itself, pure psychology or “black boxology” (which Stuart Sutherland once defined as “the ostentatious display of flow diagrams as a substitute for thought”) is unlikely to generate revolutionary advances in biology, where mapping function onto structure has been the most effective strategy. (And I would consider psychology to be a branch of biology.) I will drive home this point using an analogy from the history of genetics and molecular biology.

     Mendel’s laws of heredity, which established the particulate nature of genes, was an example of the black-box approach. These laws were established by simply studying the patterns of inheritance that resulted from mating different types of pea plants. Mendel derived his laws by simply looking at the surface appearance of hybrids and deducing the existence of genes. But he didn’t know what or where genes were. That became known when Thomas Hunt Morgan zapped the chromosomes of fruit flies with X-rays and found that the heritable changes in appearance that occurred in the flies (mutations) correlated with changes in banding patterns of chromosomes. (This would be analogous to lesion studies in neurology.) This discovery allowed biologists to home in on chromosomes—and the DNA within them—as the carriers of heredity. Which in turn paved the way for decoding DNA’s double helical structure and the genetic code of life. But once the molecular machinery of life was decoded, it not only explained heredity but a great many other previously mysterious biological phenomena as well.

     The key idea came when Crick and Watson saw the analogy between the complementarity of the two strands of DNA and the complementarity between parent and offspring, and recognized that the structural logic of DNA dictates the functional logic of heredity: a high-level phenomenon. That flash of insight gave birth to modern biology. I believe that the same strategy of mapping function onto structure is the key to understanding brain function.

     More relevant to this book is the discovery that damage to the hippocampus leads to anterograde amnesia. This allowed biologists to focus on synapses in the hippocampus, leading to the discovery of LTP (long-term potentiation), the physical basis of memory. Such changes were originally discovered by Eric Kandel in a mollusk named Aplysia.

     In general, the problem with the pure black-box approach (psychology) is that sooner or later you get multiple competing models to explain a small set of phenomena, and the only way to find out which is right is through reductionism—opening the box(es). A second problem is that they very often have an ad hoc “surface level” quality, in that they may partially “explain” a given “high level” or macroscopic phenomenon but don’t explain other macroscopic phenomena and their predictive power is limited. Reductionism, on the other hand, often explains not just the phenomenon in question at a deeper level but often also ends up explaining a number of other phenomena as well.

     Unfortunately, for many physiologists reductionism becomes an end in itself, a fetish almost. An analogy to illustrate this comes from Horace Barlow. Imagine that an asexual (parthenogenetic) Martian biologist lands on Earth. He has no idea what sex is since he reproduces by dividing into two, like an ameba. He (it) examines a human and finds two round objects (which we call testes) dangling between the legs. Being a reductionist Martian, he dissects them and, looking through microscope, finds them swarming with sperms; but he wouldn’t know what they were for. Barlow’s point is that no matter how meticulous the Martian is at dissection and how detailed an analysis he performs on them he will never truly understand the function of the testes unless he knew about the “macroscopic” phenomenon of sex; he may even think the sperm are wriggling parasites. Many (fortunately not all!) of our physiologists recording from brain cells are in the same position as the asexual Martian.

     The second, related point is that one must have the intuition to focus on the appropriate level of reductionism for explaining a given higher-level function (such as sex). If Watson and Crick had focused on the subatomic level or atomic level of chromosomes instead of the macromolecular level (DNA), or if they had focused on the wrong molecules (the histones in the chromosomes instead of DNA) they would have made no headway in discovering the mechanism of heredity.

18. Even simple experiments on normal subjects can be instructive in this regard. I will mention an experiment I did (with my student Laura Case) inspired by the “rubber hand illusion” discovered by Botvinick and Cohen (1998) and by the dummy-head illusion (Ramachandran and Hirstein, 1998). You, the reader, stand about a foot behind a bald-headed manikin looking at its head. I stand on the right side of you both and randomly tap and stroke the back of your head (especially ears) with my left hand (so you can’t see my hand) while simultaneously doing the same thing on the plastic head with my right hand, in perfect synchrony. In about two minutes you will experience that the stroking and tapping on your head is emerging from the dummy you are looking at. Some people develop the illusion of a twin or phantom head in front of them, especially if they get it going by “imagining” their head displaced forward. The brain regards it as highly improbable that the plastic head is seen to be tapped in the same precise sequence as you feel on own head by chance and so is willing to temporarily to project your head on the manikin’s shoulder. This has powerful implications since, contrary to recent proposals, it rules out simple associative learning as the basis of the rubber hand illusion. (Every time you saw your hand touched you felt it touched as well.) After all, you have never seen the back of your head being touched. It is one thing to regard your hand sensations as being slightly out of register with your real hand but quite another to project them to the back of a dummy head!

     The experiment proves that your brain has constructed an internal model of your head—even unseen parts—and used Bayesian inference to experience (incorrectly) your sensations as arising from the dummy’s head even though it is logically absurd. Would doing something like this help alleviate your migraine symptoms (“the dummy is experiencing migraine; not me”)? I wonder.

     Olaf Blanke and Henrik Ehrsson of the Karolinska Institute in Sweden have shown that out-of-body experiences can also be induced