The Best American Science and Nature Writing Part 4

Gregory was a professor of neuropsy chol ogy at the University of Bristol, the author of several best-selling books about science, and an expert in visual perception who had a special interest in optical illusions. Typical of his approach was a demonstration involving a Charlie Chaplin mask on a rotating axle, in which he shows how the brain uses prior knowledge of shape, shading, and other light effects to make sense of visual information and a.s.semble a coherent representation of the world. Gregory's playful style irritated some of his colleagues, but Ramachandran found it electrifying. "He came to Cambridge to give a lecture," Ramachandran recalls. "He was like a magician! He is truly one of the five most amazing men I have met in my life."

During his four years at Cambridge, Ramachandran commuted regularly to Bristol to design experiments with Gregory. They have since written a number of scientific papers together, including groundbreaking work on the blind spot, the region at the back of the eyeball where the retina's photoreceptors are interrupted by the optic nerve. This region creates a gap in our vision the size of a palm held at arm's length, but, owing to several strategies of the brain, we never perceive it. Using optical illusions to trick the eyes and the brain, Ramachandran and Gregory determined how the brain "fills in" the gap, and published influential articles on stroke victims suffering from scotomaa"a particularly large blind spot sometimes caused by a focal lesion in the visual cortex.

In the mid-nineties, Gregory visited Ramachandran at UCSD to undertake further experiments on scotoma, but they were unable to find a patient with a focal lesion. Instead, they spent Gregory's weeklong visit investigating a phenomenon that had long fascinated Ramachandran: the reported ability of flounder to cam ouflage itself against patterned backgrounds. Leading ichthyologists disagreed about whether the fish changed its appearance or whether the camouflage effect was an illusion. Ramachandran's local pet store had no cold-water flounder, so he bought five peac.o.c.k flounder, a related species that lives in tropical coral reefs. The men placed the fish on the bottom of four small tanks against various backgrounds: widely s.p.a.ced polka dots, a neutral gray, and two checkerboard patterns. The fish, whose natural tendency is to lie flat on the sea bottom, precisely matched on their bodies the patterns at the bottom of the tanksa"and they did so within two to eight seconds, far faster than the hours and, in some cases, days reported by researchers using cold-water flounder. Ramachandran and Gregory surmised that the rapid change was an adaptive mechanism, since the species lived among bright colors and patterns. The experiment, which they meticulously doc.u.mented in photographs and on videotape, effectively ended the debate on flounder camouflagea"and, incidentally, throws an instructive sidelight on visual processing in human beings. Even though the fish sees the background close up and in a distorted, slanted perspective, it re-creates the pattern on its body with perfect fidelity, as viewed from directly above. Human beings, Ramachandran points out, visually process the world in the same way. "Your eyeball distorts the imagea"it's curved," he says. "Your lens inverts ita"it's upside down. And your two eyes double it. The brain interprets the image."

When they wrote up the results of the experiment, Ramachandran and Gregory laced their paper with puns. In a caption for a photograph showing one fish on a polka-dot background, they wrote, "Spot the flounder," and they said that they had conducted the experiments "just for the halibut."

"So we sent this off to Nature," Ramachandran told me, "and back come the referees' comments: 'Brilliant paper, publish it right away, but remove all the puns.'" He laughed. The paper, "Rapid Adaptive Camouflage in Tropical Flounders," was published in a 1996 issue of Nature. "Since then," Ramachandran said, "I get papers on octopuses and squids and fisha"because they all think I'm an expert on ichthyology!"

In 1983 Ramachandran joined the psychology department at UCSD as an a.s.sistant professor working on visual perception. In 1991 he became interested in the work of Tim Pons, a neuroscientist at the National Inst.i.tute of Mental Health, who had been investigating the ability of neurons in the sensory cortex to adapt to change.

The sensory cortex is in the deeply ridged tissue that makes up the outermost layer of the brain. Until recently, much of what was known about it was the result of the work of Wilder Penfield, a neurosurgeon in Montreal who, beginning in the 1930s, had conducted a series of extraordinary experiments while performing open-skull operations on cancer and epilepsy patients. Seeking to distinguish healthy tissue from diseased tissue, Penfield touched the surface of his patients' brains with an electric probe, and, because the brain lacks pain receptors, the patients were fully conscious and able to talk to him about what they felt. As he stimulated different areas of the brain, his patients reported feeling touch sensations in specific parts of their bodies. In this way, over several decades and hundreds of operations, Penfield mapped areas of the brain according to their corresponding body parts. The "Penfield homunculus," as it came to be called, is oriented upside down: the areas corresponding to the feet and the legs are at the top of the brain, the arms and the hands are in the middle, and the face is near the bottom. Body parts with the greatest sensitivitya"lips, fingertipsa"take up a far larger area of the cortical surface than less sensitive areas.

The regions representing separate body parts on the Penfield homunculus, like the brain centers, were believed to be unchangeable. This view came under challenge as the technology for mapping the brain improved. Whereas Penfield had used a large electrode that affected thousands of neurons at a time, brain researchers in the fifties began to use tiny microelectrodes, which could be inserted into the brains of animals to record the firing of single neurons and, thus, communication among them. In the seventies, Michael Merzenich became expert at using microelectrodes to map the sensory cortex of monkeys. In one experiment, he mapped a monkey's hand area in the brain, then amputated its middle finger. Some months later, he remapped the monkey's hand and discovered that the brain map for the missing finger had vanished and been replaced by maps for the two adjacent fingers, which had spread to fill the gap. The results, published in the Jour nal of Comparative Neurology in 1984, were decisive proof that the brain can reorganize itselfa"at least across very short distances of one to two millimeters.

Pons, at NIMH, was curious to know whether the brain could accomplish more dramatic reorganizations, across greater distances. He wondered what happened in the brains of monkeys that had lost brain input from an entire hand and arm, and he thought that he could procure some animals to test. In 1981 a member of PETA had infiltrated a Maryland lab where a researcher studying stroke paralysis had severed the sensory nerves in a group of macaque monkeys that connected the animals' arms to their spinal cordsa"a procedure known as deafferentation. PETA released photographs of the monkeys, and the animals were seized and placed in the custody of the National Inst.i.tutes of Health. By 1990 the monkeys had grown old and were about to be euthanized. Pons successfully appealed to the NIH to allow him to conduct a final experiment on four of them.

Pons anesthetized the first animal, opened its skull, and inserted electrodes into the brain-map area for the deafferented arm. He stroked the corresponding limb. As expected, the brain electrodes recorded no activity, since no messages were being sent to the brain from the arm. But when Pons stroked the monkey's face, the neurons in the map of the deafferented arm began to fire. The experiment showed that the neurons in the face map had invaded the area of the hand-and-arm map, which had been inactive for twelve years. Fourteen millimeters of the monkey's arm map had been reorganized to process sensory input from the face. Pons repeated the experiment on three more monkeys and published the results in Science in 1991, as a paper t.i.tled "Ma.s.sive Cortical Reorganization After Sensory Deafferentation in Adult Macaques."

Ramachandran read Pons's paper and wondered whether it could help solve the long-standing medical puzzle of phantom limbs. Many amputees continue to experience sensationsa"often painfula"from a missing limb, and the phenomenon has baffled scientists since it was first reported, in the sixteenth century, by the French surgeon Ambroise Par. Ramachandran says that his interest in phantom limbs was a natural extension of his work in visual processing. "I was interested in the 'filling in' of the blind spot and other holes in the visual field; how the brain deals with undersam pled regionsa"gaps," he said. "This resulted in my asking, 'How do you "fill in" a missing limb?'" Pons's monkeys seemed to offer a clue.

"Often, the best experiments begin as jokes," Ramachandran told me. "I joked with my students. I said, 'Hey, this means that if I touch the monkey's face the monkey should feel it in the hand.' And they all laughed, and I said, 'Hey, why not?' Then they said, 'Well, how do you train a monkey to tell you what it's feeling?' And I said, 'Why do you need a monkey? Let's try it on a person.'"

Ramachandran arranged to examine a seventeen-year-old boy whom he calls Tom, who had recently lost his left arm, just above the elbow, in a car crash. In a bas.e.m.e.nt lab at Mandler Hall, Ramachandran lightly stroked Tom's cheek with a Q-Tip. Tom said that he felt the touch in his cheek but also in his phantom thumb. A touch on the lip he felt on his phantom index finger, a touch on the lower jaw in his phantom pinkie. Ramachandran realized that every time Tom moved his face and his lipsa"smiling, talking, frowninga"the nerve impulses from his face activated the "hand" area in his cortex. "Stimulated by all these spurious signals," he later wrote, "Tom's brain literally hallucinates his arm."

Ramachandran immediately telephoned his wife, Diane Rogers-Ramachandran, and told her, "Come in right now. You've got to see this guy."

Rogers-Ramachandran is also a scientist, specializing in vision and experimental psychology. She and Ramachandran met in the late 1970s at a vision conference in Florida. She was then a graduate student at the University of North Carolina, Chapel Hill. They married in 1987. (They have two boys: Chandramani, who is nineteen, and Jaya, fourteen.) Rogers-Ramachandran rushed from their home in nearby Del Mar to watch the experiment. In the course of a few hours, she and her husband mapped Tom's phantom hand on his face. In a later experiment, they applied warm water to Tom's cheek. He felt heat in his phantom hand. When the water trickled down his cheek, he felt it running down his phantom arm. Ramachandran and his wife published their findings in 1992 in Science.

Rogers-Ramachandran, a vivacious woman with bright blue eyes, continues to collaborate with her husband on papers, and they write a regular science column for Scientific American Mind. She says that it has sometimes been a challenge to be married to a man of Ramachandran's mental energy and intellectual curiosity. "Like, when we got married," she said one evening, over dinner at a restaurant with her husband and Jaya, "we went to England for our honeymoon and spent the whole time going to bookstores and collecting prints, books, scientific instruments. Never went to a play! None of those things! The collecting! He went from scientific instruments to fossils, to learning about his Indian heritage, to art. You say, 'Well, can't we just go walk on the beach?'"

She mentioned Ramachandran's abstracted aira"it's as if he were constantly mulling over an abstruse neurological conundrum. I knew something about this. On the first day of my visit to UCSD, Ramachandran was unable to remember where in the parking lot he had left his car and finally had to activate the alarm on the remote control to locate it. His embarra.s.sment suggested that this was the first time such a thing had happened. Yet during the six days that I spent with him, it happened every time. When I told this story to Diane at dinner, she snorted.

"When we leave a place, he'll go into the parking lot, and a lot of time he'll just start walking," she said. "He has no idea where he's going. He just walks. One time I picked him up from a tripa""

"Oh, don't tell him that," Ramachandran said.

But Diane went on. "He reached in his pocket and he said, 'Oh, my G.o.d, I had a rental car in that city! I completely forgot! I have the keys and I didn't turn the car in!' Another time," she continued, "I got a call from Sears and a woman said, 'There's a man here who says he's your husband and he's trying to purchase something on this credit card.' I said, 'Ye-e-e-s.' And she said, 'We're kind of concerned if it's really your husband, because he doesn't know your birth date.' I said, 'Oh, that's my husband!'"

"Ha-ha-ha-ha-ha!" Ramachandran boomed. "That is a good story."

I could not resist asking whether Ramachandran had since learned Diane's birthday. They have been married for twenty-two years.

"I know she's a Leo," he said slowly, eying her from across the table.

"I'm not a Leo," Diane said. "You're a Leo."

"No," he corrected himself. "Virgo! Virgo!"

"Yup," she said.

"August eighteenth," he said with confi dence.

"No," Diane said. Then she turned to me. "See, he gets the month, because it's the same as his."

"It's not the eighteenth?" Ramachandran asked.

"No."

"Twenty-second?" he offered.

"No."

At this point, Jaya asked, "Do you know my birthday?"

Ramachandran looked helplessly at his son and shrank into his seat. "It doesn't mean I don't love you," he said.

In 1994 Ramachandran published a paper in Nature that is now considered a landmark in the field of neuroplasticity. He described experiments that he had conducted with UCSD's multimillion-dollar magnetoencephalography machine, which records the changing magnetic fields caused by brain activity. (Though he calls himself a "technophobe," Ramachandran occasionally uses high-tech gadgetry, chiefly as a means to support his hunches.) The high-resolution MEG scans clearly showed that in the brains of arm amputees the area a.s.sociated with the face had invaded the area a.s.sociated with the missing arma""the first direct demonstration of ma.s.sive reorganization of sensory maps in the adult human brain," Ramachandran wrote.

His most startling revelation about the brain's capacity for reorganizing itself was yet to come. It emerged from his efforts to address phantom-limb pain, which afflicts up to 90 percent of amputees. Some report feeling that they are clenching their phantom fist so hard that their phantom fingernails are digging into their phantom palm. Phantom-limb pain can be so agonizing that some sufferers commit suicide.

For more than a century, doctors theorized that the pain was psychological or originated in the stumpa"in swollen nerve endings called neuromas. Some resorted to repeated amputations, making the stump shorter and shorter. When this didn't work, they tried severing the nerves at the spinal cord and even disabling parts of the thalamus, an organ at the base of the brain that processes pain. All to no avail. "They can chase the phantom farther and farther into the brain, but of course they'll never find it," Ramachandran once wrote. The phantoms, as he had shown, are produced in the sensory cortex, where neurons for the face have invaded territory once reserved for the arm.

Ramachandran posited that the phantom sensations are also created by higher brain centers, produced by a complex interplay among the sensory cortex, the motor cortex in the frontal lobes, and a "body image" map in the right superior parietal lobule, a section of the cerebral cortex just above the right ear. One of the main tasks of the right superior parietal lobule is to a.s.semble a coherent body image from touch signals ("I feel my fingers touch the cup"), visual signals ("I see my hand reaching for the cup"), and nerve signals from the muscles, joints, and tendons ("I feel my arm extending toward the cup"). Even though amputees no longer received these signals from the nonexistent limb, Ramachandran believed that memories of these inputs remained in the nervous system and the brain.

Reviewing the histories of amputees, Ramachandran noticed that many who suffered from cramping or clenching spasms had experienced, before their amputations, a period during which the limb was immobilized, sometimes for months, in a sling or a cast. He theorized that a kind of "learned paralysis" was burned into the brain's circuitry, as repeated commands from the patients' brains to move the limb were met with touch, visual, and nerve evidence that the limb could not move. When the limb was later amputated, the patient was stuck with a revised body-image map, which included a paralyzed phantom whose neural pathways retained a memory of pain signals that could not be shut off. Ramachandran wondered what would happen if such a patient was presented with evidence that the phantom could move ("I see my hand reaching for the cup"). If the brain could be tricked into thinking that the phantom was moving, would the cramping sensations cease?

His first test subject was a young man who a decade earlier had crashed his motorcycle and torn from his spinal column the nerves supplying his left arm. After keeping the useless arm in a sling for a year, the man had the arm amputated above the elbow. Ever since, he had felt unremitting cramping in the phantom limb, as though it were immobilized in an awkward position.

In his office in Mandler Hall, Ramachandran positioned a twenty-inch-by-twenty-inch drugstore mirror upright and perpen dicular to the man's body and told him to place his intact right arm on one side of the mirror and his stump on the other. He told the man to arrange the mirror so that the reflection created the illusion that his intact arm was the continuation of the amputated one. Then Ramachandran asked the man to move his right and left arms simultaneously, in synchronous motionsa"like a conductora"while keeping his eyes on the reflection of his intact arm. "Oh, my G.o.d!" the man began to shout. "Oh, my G.o.d, Doctor, this is unbelievable." For the first time in ten years, the patient could feel his phantom limb "moving," and the cramping pain was instantly relieved. After the man had used the mirror therapy ten minutes a day for a month, his phantom limb shranka""the first example in medical history," Ramachandran later wrote, "of a successful 'amputation' of a phantom limb."

Ramachandran conducted the experiment on eight other amputees and published the results in Nature in 1995. In all but one patient, phantom hands that had been balled into painful fists opened, and phantom arms that had stiffened into agonizing contortions straightened. "People always ask, 'How did you think of the mirror?'" Ramachandran told me. "And I say, 'I don't know!' There was a mirror in the lab, so that must have been in my mind, and I said, 'Let's try it.' It's not any more mysterious than if you say something 'popped into' your mind."

Dr. Jack Tsao, a neurologist for the U.S. Navy, was doing graduate work in physiology at Oxford University when he read Ramachandran's Nature paper on mirror therapy for phantom-limb pain. "I said, 'Why the heck should this work? It doesn't make sense,'" Tsao told me. Several years later, in 2004, Ts...o...b..gan working at Walter Reed Military Hospital, where he saw hundreds of soldiers with amputations returning from Iraq and Afghanistan. Ninety percent of them had phantom-limb pain, and Tsao, noting that the painkillers routinely prescribed for the condition were ineffective, suggested mirror therapy. "We had a lot of skepticism from the people at the hospital, my colleagues as well as the amputee subjects themselves," Tsao said. But in a clinical trial of eighteen service members with lower-limb amputations, in which six were given mirror therapy and the twelve others were evenly divided between two control therapies (a covered mirror and mental visualization), the six who used the mirror reported that their pain decreased (and, in some cases, disappeared altogether). In the two control groups, only three patients reported pain relief, and others found that their pain increased. Tsao published his results in the New England, Journal of Medicine in 2007. "The people who really got completely pain-free remain so, two years later," said Tsao, who is currently conducting a study involving mirror therapy on upper-limb amputees at Walter Reed.

Buoyed by these successes, in the mid-nineties Ramachandran abandoned his work in visual perception to devote himself to neurology. "Vision was getting overcrowded," he told me. Neurology seemed like virgin territory. Much of the specialty was concerned with describing strange syndromes rather than with explaining their cause or alleviating symptoms. "You've got a hundred papers saying, 'My G.o.d, they can move their phantom'a"but it stayed at that level, a descriptive level," Ramachandran said. "We said, 'Look, we can do experiments. What if you do this to the patient?' And I took that same style to other syndromes. Then the sky was the limit. No one was studying these things."

Gradually, Ramachandran began to specialize in rare conditions and disorders, including the Capgras delusion, in which an otherwise lucid victim of a head injury insists that close loved ones (spouses, parents, children) are impostors. Freudians had theorized that Capgras patients were suffering from unbearable Oedipal desires aroused by the blow to the head, but Ramachandran demonstrated that severed neural pathways between the facial-recognition areas of the visual cortex and the emotional centers of the brain were responsible for the disorder. He also investigated post-stroke syndromes, in which patients deny that a paralyzed limb has become immobile or, in a more severe version, insist that the paralyzed arm or leg belongs to someone else. Ramachandran traced the delusion to damage in the right superior parietal lobule, the body-map region, where the discrepancy between the absence of signals from the limb to the brain and the presence of the limb on the body results in a defensive rationalization that the arm or leg must be someone else's. A few years ago, Ramachandran began studying apotemnophilia, the compulsion to amputate a healthy limb. He is, he said, "ninety-five percent sure" that he has figured out the cause of the disorder. His consultation with Arthur Jamieson strengthened this conviction.

After interviewing Jamieson in his office, Ramachandran led him to a lab for a galvanic skin response, or GSR, test, which would reveal how Jamieson's legs reacted to a mild pain stimulus. He escorted Jamieson into a small room that held only a table, a desktop computer, and two chairs. He asked Jamieson to sit with his back to the computer. Then David Brang, one of Ramachandran's graduate students, attached a sensor to the middle two fingers of Jamieson's right hand using a Velcro strap. The sensor would measure the reaction of Jamieson's sympathetic nervous system by monitoring the sweat on his fingers. With a sterilized pin, Brang p.r.i.c.ked Jamieson's legs at random points, waiting a few seconds between each p.r.i.c.k. A scrolling graph on the computer screen registered Jamieson's responses.

The unaffected lega"the left onea"and the right leg above where he wished to have it amputated showed a normal response: the graph at first shot upward with each p.r.i.c.k, but with further p.r.i.c.ks it ceased to rise, then began to flatten out, indicating that Jamieson's nervous system was getting used to the stimulus. But when Brang p.r.i.c.ked Jamieson anywhere on the leg below the amputation line, his nervous system responded with increasing distress, the graph climbing higher and higher with each p.r.i.c.k.

The experiment seemed to support Ramachandran's theory about the disorder. He believed that people with apotemnophilia had a deficit in the right superior parietal lobule, where the body-image map is a.s.sembled. According to this notion, Jamieson was missing the neurons in the map that corresponded to his right leg from the midthigh down. He had normal sensation in the unwanted part of his lega"he felt the pin p.r.i.c.k. But when the pain signal traveled to the right superior parietal lobule, there was nothing in the body-image map to receive it.

"So there's a big discrepancya"a clasha"and the brain doesn't like discrepancies," Ramachandran said. "When a discrepancy comes in, it says, 's.h.i.+t! What the h.e.l.l is going on here?' and it kicks in and sends a message to the insular part of the brain, which is involved in emotional reactionsa"so you're getting this crazy GSR." In apotemnophilia sufferers, the discrepancy causes a feeling of distress that is no less agonizing for being below the level of conscious awareness.

In the past two years, Ramachandran has tested four other apotemnophiliacs using MEG brain scans. "You touch them any where in the body and the right superior parietal lobule lights up, as you would expect," Ramachandran said. "But if you touch him here"a"he gestured to a point on Jamieson's leg below the amputation linea""nothing happens." Ramachandran said that the experiment needed to be repeated by other researchers, but, he added, "This takes a spooky psychological phenomenon and, as Shakespeare said, gives it a 'habitation and a name.'" Furthermore, the findings suggested to Ramachandran a possible method for alleviating the oppressive sensations in the unwanted limb.

Later, he asked Jamieson to stand in a corner of his office and placed a three-foot-high mirror in front of him in such a way that in place of his right leg Jamieson saw his left, which he held bent at the knee. Jamieson gazed into the mirror. "Astonis.h.i.+ng," he said. For a moment, the leg looked "right."

The mirror was a less risky kind of sham amputation than the method that Jamieson had recently adopted: injecting anesthetic to block the sciatic nerve of his right leg, shutting down the touch sensation. (As a physician, Jamieson had learned how to perform the nerve block.) The anesthetic provided up to five hours of relief, Jamieson said. Apotemnophiliacs, like transs.e.xuals, anorexics, and others with body-image disorders, often do not seek a "cure" for their condition, and Ramachandran spoke gingerly when he suggested that using both the mirror and the drug could potentially yield powerful results. "It's conceivablea"n.o.body knowsa"but if you do this repeatedly, and I'm not suggesting that you try this, because I know you don't want to be 'changed,' but if you do it repeatedly, both the injections and the visual amputation, it might actually eliminate this desire," he said.

Ramachandran describes his approach to science as "opportunistic": "You come across something strangea"what Thomas Kuhn, the famous historian and philosopher of science, called 'anomalies.' Something seems weird, doesn't fit the big picture of sciencea"people just ignore it, doesn't make any sense. They say, 'The patient is crazy.' A lot of what I've done is to rescue these phenomena from oblivion." Ramachandran is conscious of the fact that this focus might lead some to think that he works on the margins of his field. "Now, you could say that about Oliver," he told me, referring to his friend and colleague Oliver Sacks, the neurologist and author of The Man Who Mistook His Wife for a Hat. "'Oh, he studies spooky things,'" Ramachandran went on. "That's bulls.h.i.+t. This man has deep insight into the human condition. He's a poet of neurology." Ramachandran says that his own interest in oddities is not for their own sake but for what they can tell us about the normal brain, including, he said, "very enigmatic aspects of the brain that few people have dared to approach, like what is a metaphor? How do you construct a body image? Things of that nature."

In 1999 Ramachandran turned his attention to synesthesia, an intermingling of the senses that causes some people to see each letter of the alphabet in a particular color. Others identify musical notes with colors; still others mix touch sensations with strong emotions, so that sandpaper might evoke disgust; velvet, envy; wood grain, guilt. Vladimir Nabokov described his letter-color synesthesia in Speak, Memory: "I see q as browner than k, while s is not the light blue of c, but a curious mixture of azure and mother-of-pearl." As an artist, Nabokov was, according to Ramachandran's research, eight times more likely to have synesthesia than someone who is not an artist; the fact that Nabokov's mother also had the condition suggested a genetic component. (The phenomenon runs in families.) The most common synesthesia is number-color. Ramachandran believed it was not coincidental that the fusiform gyrus, where number shapes are processed in the brain, lies next to the area where colors are processed. He suspected that a cross-wiring in the brain, similar to that in phantom-limb patients, was responsible. Brain scans confirmed his hunch: in synesthetes, there are excess neural connections between the two brain centers. This suggested to Ramachandran that the syndrome arises from a defect in the gene responsible for pruning away the neural fibers that connect the various centers of the brain as it develops early in life. "What do artists, poets, and novelists have in common?" Ramachandran asked me. "The propensity to link seemingly unrelated things. It's called metaphor. So what I'm arguing is, if the same gene, instead of being expressed only in the fusiform gyrus, is expressed diffusely through the brain, you've got a greater propensity to link seemingly unrelated brain areas in concepts and ideas. So it's a very phrenological view of creativity."

In the mid-nineties, Ramachandran read a paper by Italian researchers who had discovered that a set of neurons in the frontal lobes of monkeys fired not only when the monkeys reached for an object but also when they observed another monkey performing the same action. Ramachandran wondered if these so-called "mirror neurons" also exist in humansa"a difficult thing to test, since the Italians had inserted electrodes into the brains of living monkeys, a technique that it is impossible to use on people. But Ramachandran knew of experiments from the 1950s in which noninvasive EEG scans were used. These had shown that deliberate movements in humans suppress a kind of brain activity in the motor cortex called mu waves. Ramachandran and a postdoctoral fellow, Eric Altschuler, ran EEGs on volunteers as they observed another person performing an action such as opening and closing a hand. The tests showed that merely witnessing an action in others caused mu-wave suppression in the watchera"evidence that mirror neurons exist in humans, too. Other researchers have since confirmed that people have several systems of mirror neurons, which perform different functions.

"So let's take the broader theoretical implications of this," Ramachandran said one afternoon while we were visiting the San Diego Rehabilitation Inst.i.tute at Alvarado Hospital, where he had examined a paralyzed stroke patient suffering from limb denial. He was sitting in the hospital cafeteria with the clinic's medical director, Lance Stone. "These mirror-neuron experiments are showing that, through and through, the brain is a dynamic system not only interacting with your skin receptors, up here"a"he pointed at his own heada""but with Lance!" He pointed across the cafeteria table at Dr. Stone. "Your brain is hooked up to Lance's brain! The only thing separating you from Lance and me is your b.l.o.o.d.y skin, right? So much for Eastern philosophy." He laughed, but he wasn't kidding. Ramachandran has dubbed mirror neurons "Gandhi neurons"a""because," he said, "they're dissolving the barrier between you and me."

Ramachandran wondered whether mirror neurons were implicated in autism, a condition whose primary characteristic is severe social impairment, including an inability to imitate and a lack of empathy. Ramachandran, Altschuler, and Jaime Pineda, a UCSD colleague, ran EEGs on autistic children. They got normal mu-wave suppression when the subjects moved their own hands. But when the children watched another person move his hand, their brains didn't respond. At a neuroscience conference in 2000, Ramachandran and his coauthors presented their findings and speculated that autism was caused by a deficit in the mirror-neuron system. The idea initially met with resistance from autism researchers, some of whom argue that the disorder is caused primarily by deficits in the cerebellum. Unlike his earlier foray into ichthyology, Ramachandran was entering a sphere of science fraught with politics. "The trouble is, it's a minefield," he told me. "The parents are involved. There's big money involved. Suppose you invested your life in saying that the cerebellum is what's going on, then someone comes along and spends one year on it and says, 'It's the mirror-neuron system'?"

In the past nine years, however, mirror neurons have become a central topic in autism research. Almost at the same time as Ramachandran, a group in Scotland had also suggested the link. Among those who have provided further evidence are researchers at the Helsinki University of Technology, who used MEG scans to show mirror-neuron deficits in autistic teenagers and adults. Lindsay Oberman, a former graduate student of Ramachandran's, who now works as a postdoctoral fellow at Beth Israel Deaconess Medical Center in Boston, has begun using a technology called trans-cranial magnetic stimulationa"a technique that triggers targeted areas of neurons in the braina"to influence brain plasticity in autistics. "So far, we have done some amazing things," Oberman has written. "We have found evidence that we can improve the functioning of the mirror-neuron system and some communication skills following repeated application of TMS."

On the last day of my visit with Ramachandran, I attended the lab discussion that he holds each Monday with his postdoctoral and graduate students at the Center for Brain and Cognition Laboratory, on the second floor of Mandler Hall. The lab, a room of modest size, was dominated by a long central table heaped with the strange tools of Ramachandran's trade: a foam-rubber hand of the type you buy at a horror shop (for a demonstration that Ramachandran likes to do to show visitors how the brain projects touch sensations onto objects that are not part of the body); a mirror ball of the type that M. C. Escher liked to draw; a boxed set of the BBC miniseries of Sherlock Holmes (for inspiration); several plastic minimizing lenses (Ramachandran has found that viewing a painful arm or leg through a lens that makes the limb look smaller dramatically reduces pain); a reflective metal tube that could be twisted into various amoebic shapes (when I asked if this puzzle had "experimental significance," Ramachandran said, "No," then quickly corrected himself: "Well, it's fun"); a series of oddly shaped metal boxes outfitted with slanting mirrors (for inducing perceptual distortions in those who peer through the eyeholes); and a plaster cast of Minotaurasaurus ramachandrani, a creature that resembles a medieval gargoyle, with three nasal openings on either side of its ridged and crenellated head. Ramachandran has asked one of his postdocs, Paul McGeoch, to perform a CAT scan of the skull in order to learn about the creature's olfactory lobes, and, in this way, to test Ramachandran's theory that his ankylosaur's heightened sense of smell might allow the beast to sniff out mates or carrion from a great distance (although it was more likely a vegetarian).

Seated around the table were members of Ramachandran's research group. Most were in their middle to late twenties, except for a man in his eighties with a British accent: John Smythies, whom Ramachandran introduced to me as the person who launched the drug revolution in the sixties. Smythies demurred, explaining that as a postdoc at Cambridge in the fifties, while performing psychopharmacology experiments involving mescaline, he had merely introduced Aldous Huxley to a colleague, who then administered to Huxley the hallucinogens that led him to write The Doors of Perception, which later became a bible of the Woodstock generation.

Ramachandran, who was dressed in his usual black leather jacket and dark polo s.h.i.+rt, took a seat at the table and fielded questions from his students, helping them to refine their methodologies and using the brisk interchanges to hone ideas for research. At one point, Lisa Williams, a Ph.D. student who specializes in schizophreniaa"a disorder that Ramachandran first began exploring about a decade agoa"mentioned in pa.s.sing the difficulty that schizophrenics have in differentiating between phenomena that are internally and externally generated.

"Oh!" Ramachandran cut in. "Speaking of that, I have an ideaa"I'm sure it's been donea"but you know that when people think to themselves you get unconscious movements of the vocal cords? Now, has anybody done that with schizophrenia to see if it's enhanced?"

"I don't know," Williams said. "I'll look that up."

If such enhanced subvocalization occurs when schizophrenics think, that would support Ramachandran's view of the brain as an organ in dynamic equilibriuma"and of mental illnesses as resulting from a neurological disruption that destroys that equilibrium. In the case of schizophrenia, whose sufferers often complain of "hearing voices," Ramachandran suspected damage or deficit in a sensory mechanism in the vocal cords, which, when normal people think, sends a signal to the brain indicating "This is simply a thought; no one is actually saying this." If this mechanism was damaged, the subconscious movement of the vocal cords could be interpreted as an outside voice speaking in one's head.

"By the way," Ramachandran continued, "I have a theory that if you take people with carcinoma of the larynx, and you remove the vocal cords, and they think to themselves, they may actually start hallucinating. A prediction."

This remark prompted Laura Case, a first-year graduate student who has focused on autism, to speak. "That could be interesting in autism, too," Case said. "Because if they lack the robust mirror activation for actions, which they doa""

Ramachandran interjected, "Then they confusea"so they may confuse their own vocalizations with somebody else's! And people have linked autism to schizophrenia. The old theory was that it was early-childhood schizophrenia! Was that a coincidence?"

The discussion proceeded in this freewheeling manner for more than an hour, with Ramachandran seizing on notions that seemed to offer fruitful possibilities for further investigation and tactfully deflecting those which he thought were dead ends. When the discussion ended, at 6 P.M., and Ramachandran's students had departed, I asked him if he thought that his work was aimed at constructing a "grand unified theory" of the brain. He said that neuroscience was still too young a discipline for such an ambition. Nevertheless, in recent years he has increasingly focused on the biggest mystery of the brain: consciousness. Mirror neurons play a role, he thinks. "One of the theories we put forward," he said, as he packed up his bag, "is that the mirror-neuron system is used for modeling someone else's behavior, putting yourself in another per son's shoes, looking at the world from another person's point of view. This is called an allocentric view of the world, as opposed to the egocentric view. So I made the suggestion that at some point in evolution this system turned back and allowed you to create an allocentric view of yourself. This is, I claim, the dawn of self-awareness."

Still, Ramachandran said, deciphering how consciousness works will take a supreme creative leap. "It may require a radical revision of the way in which you perceive the universe, the world, the brain," he said, as he stepped into the hallway and locked the lab door behind him. "Just like Einstein had to change your complete perspective in order to really understand time, saying it's part of the whole s.p.a.ce-time manifold. Things don't 'pa.s.s through' timea"that's a human illusion. But if it requires that, some genius is going to have to come along and solve it." He opened the door to the stairwell and started down. "What we're hoping," he went on, "is that we can grope our way toward the answer, finding little bits and pieces, little clues, toward understanding what consciousness is. We've just scratched the surface of the problem. When I say 'we,' not just our lab but the entire world of neuroscience."

By now, we had reached the ground floor of Mandler Hall and were walking outside, past cl.u.s.ters of students. Ramachandran was still speaking excitedlya"he had veered into a knotty digression about the brain's role in the evolution of languagea"when he glanced up and realized that we had reached the parking lot. He stopped talking and looked out over the sea of automobiles.

"Uh-oh," he said.

PART THREE.

Natural Beauty.

GUSTAVE AXELSON The Alpha Accipiter.

FROM Minnesota Conservation Volunteer.

ON A PLEASANT SUMMER DAY in Chippewa National Forest, I was strolling down a woodsy traila"until I crossed a boundary where I was unwelcome. A screaming goshawk hurtled out of the forest shadows.

Kee-kee-kee-kee-kee! Its high-pitched, incessant alarm call pulsated like a siren. The hawk fluttered from perch to perch amid the leafy treetops, then settled atop a dead aspen to a.s.sume an aggressive posture. Its undertail feathers flared, a snow white, fluffy plume befitting this bird's Latin name: Accipiter gentilis, a raptor of gentility.

Kee-kee-kee-kee-kee! The strident refrain continued. The goshawk protested with agitated bobs of its head. Its red eyes burned like hot, glowing coals embedded in its dark gray facial stripes.

Kee-kee-kee-kee-kee! The message was clear: Leave.

"She must have nestlings," said the Department of Natural Resources Nongame Wildlife biologist Maya Hamady, indicating that the goshawk's young must have already hatched. "The female doesn't leave the nest when she's sitting on eggs."

Hamady had agreed to guide me to one of the 109 goshawk nest sites in northern Minnesota that the DNR and other agencies have been monitoring since 1991. As she records goshawk nesting activity, Hamady is filling a void in Minnesota's avian annals. No one has ever conducted a comprehensive survey of goshawk populations in Minnesota, so biologists don't really know how many goshawks live in our north woodsa"or how they are faring.

But this lack of a historical baseline for evaluating the goshawk's conservation status doesn't stop Hamady from looking into the future of Minnesota forests to see if goshawks will have enough closed-canopy habitat for nesting. Habitat fragmentation and declining stands of mature aspens could pose challenges for goshawks as they seek nesting territories over the next two decades and beyond.

A Fierce Reputation.

The northern goshawk is the largest Minnesota accipiter, a genus of forest-dwelling, fast-flying hawks that includes Cooper's and sharp-s.h.i.+nned hawks. The goshawk's ferocity is legendary. It has been known to attack other hawks, people, even black bears. Attila the Hun rode into battle wearing a helmet that bore an emblem of this most truculent bird of prey.

Hamady has experienced the accipiter's aggressiveness firsthand on several nest-site checks, when goshawks swooped at her. On one visit, a goshawk flew overhead for most of her quarter-mile retreat to her car.

She also witnessed a prime example of the goshawk's territorial tendencies. "I once got a call from a landowner about a goshawk nest, but when I went out to confirm it I only saw a sharp-s.h.i.+nned hawk. So I thought the landowner was mistaken," Hamady said. Later another raptor researcher visited the nest and found two fledgling goshawks and the skeleton of a sharp-s.h.i.+nned hawk on the ground below.

Goshawks hunt by executing surgical strikes in thick woodsa"weaving among tree boles, flying at speeds up to fifty-five miles an hour. Relentless in pursuit of prey, a goshawk will crash through brush at top speed and even drop to the ground to run down its quarry on foot.

The goshawk's choice of prey has tarnished its reputation among some hunters, who worry that the "grouse hawk" could depress local game bird populations. But a 2003 research study of northern goshawk food habits in Minnesota revealed a broad diet. Over forty-five days, a pair of breeding goshawks averaged two daily deliveries of prey, including twenty-nine red squirrels, fourteen eastern chipmunks, six crows, five snowshoe hares, five ruffed grouse, two diving ducks, one cottontail rabbit, one blue jay, and thirty-one miscellaneous forest creatures (including pileated woodp.e.c.k.e.rs, a weasel, and a veery).

Dense Woods Denizen.