Brain Games.(apotemnophilia )

One morning in January, a tall, gray-haired man whom I will call Arthur Jamieson arrived at the Mandler Hall psychology building, at the University of California, San Diego, in La Jolla. Jamieson is seventy years old and lives in the Midwest. He is a physician and an amateur cellist, and has been married for forty-seven years. He also suffers from a rare and bewildering condition called apotemnophilia, the compulsion to have a perfectly healthy limb amputated--in his case, the right leg, at mid-thigh. He had come to La Jolla not to be cured of his desire (like most people with the syndrome, he believed that relief would come only with the removal of the limb) but to gain insight into its cause. To that end, he had scheduled a meeting with Dr. Vilayanur S. Ramachandran, an Indian-born behavioral neurologist who is the director of the Center for Brain and Cognition at U.C.S.D., and has a reputation among his peers for being able to solve some of the most mystifying riddles of neuroscience.

Ramachandran, who is fifty-seven, has held prestigious fellowships at All Souls College, in Oxford, and at the Royal Institution, in London. His 1998 book, "Phantoms in the Brain," about rare neurological disorders, was adapted as a miniseries on BBC television, and the Indian government recently accorded him the title Padma Bhushan, the country's third-highest civilian honor. But it is the awe that he inspires in his scientific colleagues that best illuminates his position in neuroscience, where the originality of his thinking and the simple elegance of his experiments give him a unique status. "Ramachandran is a latter-day Marco Polo, journeying the silk road of science to strange and exotic Cathays of the mind," Richard Dawkins once wrote. Eric Kandel, the Columbia University neuroscientist whose work on the physiological basis of learning and memory earned him a Nobel Prize in 2000, invoked two pioneering brain scientists to describe Ramachandran's contribution to the field: "He is a continuation of a tradition in neurology that goes back to the nineteenth century, to giants like Broca and Wernicke, who gave us, from studying clinical material, enormous insights into the functioning of the human mind."

Ramachandran, who has dark skin, curly black hair, and a mustache, cultivates a slightly rebellious image, often wearing dark polo shirts and a black leather jacket. However, when he meets with patients he tends to dress more conservatively. The day that he met with Jamieson, he was wearing a wool blazer and a tie. He greeted Jamieson in his office, whose decor reflects Ramachandran's many interests outside neurology: Darwinian evolution, plate tectonics, Indian art, Victorian medicine, paleontology, optical illusions. A four-foot stone sculpture of the god Shiva stood behind his desk. On one wall, there was a three-hundred-million-year-old fossil of a mesosaur, a freshwater reptile found only in South America and Africa (and which, as Ramachandran likes to explain, is a central piece of evidence in the theory of continental drift). On a side table was an array of antique scientific items: a brass Gilbert telescope, a hand-cranked electrical machine for curing "nervous diseases," a box of glass tubes containing Victorian homeopathic medicines. Another table held what appeared to be a smoothly sanded wooden sculpture of a woman's pelvis. Ramachandran often tells visitors that the object is a Henry Moore, before revealing, with a booming laugh, that it is actually a specimen of the world's largest seed, from the coco-de-mer palm.

Ramachandran listened closely as Jamieson talked about his condition. In a specialty that today relies chiefly on the power of multimillion-dollar imaging machines to peer deep inside the brain, Ramachandran is known for his low-tech method, which often involves little more than interviews with patients and a few hands-on tests--an approach that he traces to his medical education in India, in the nineteen-seventies, when expensive diagnostic machines were scarce. "The lack of technology actually forces you to be ingenious," he told me. "You have to rely on your clinical acumen. You have to use your Sherlock Holmes-like deductive abilities to figure things out."

Ramachandran suspected that apotemnophilia was a neurological disorder and not, as Freudians have theorized, a psychological syndrome associated with repressed sexual desires. After interviewing several apotemnophiliacs--Jamieson is the fifth person with the disorder whom he has studied--Ramachandran was struck by the fact that all of them said they became aware of the compulsion in early childhood, that it centered on a particular limb (or limbs), that they could draw a line at the exact spot where they wanted the amputation to occur, and that they attached little or no erotic significance to the condition. Furthermore, none rejected the limb as "not belonging" to them, as some stroke victims do in the case of a paralyzed arm or leg, and as Ramachandran had predicted they might. Instead, they said that the limb over-belonged to them: it felt intrusive. "If you talk to independent apotemnophiliacs, they say the same bloody things," Ramachandran told me. " 'The line for cutting is here.' 'It started in early childhood.' 'It's over-present.' They're not crazy."

Jamieson, who was born and raised in New York City, first remembers having an unusual relationship with his right leg when, at around the age of seven, he was waiting for a bus. He found himself thinking that if he stuck out his leg it would be crushed and severed by the bus. "What came to me was not 'No, I don't want to do that' but 'How would I ever explain this?' " he told Ramachandran. In recounting his childhood memories, he said, "One of the things that's astonishing to me is how clear these recollections are."

"These things are very salient," Ramachandran said in a resonant baritone, which carries a British-inflected Indian accent. "It's interesting to contrast these very clear-cut descriptions with these vague, Freudian notions about this whole phenomenon--that it's primarily connected with sexual stuff."