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Henry Gustav Molaison (February 26, 1926 – December 2, 2008), known widely as H.M., was an American man who had a bilateral medial temporal lobectomy to surgically resect the anterior two thirds of his hippocampiparahippocampal corticesentorhinal corticespiriform cortices, and amygdalae in an attempt to cure his epilepsy. Although the surgery was partially successful in controlling his epilepsy, a severe side effect was that he became unable to form new memories.

The surgery took place in 1953 and H.M. was widely studied from late 1957 until his death in 2008.[1][2] He resided in a care institute in Windsor Locks, Connecticut, where he was the subject of ongoing investigation.[3] His case played an important role in the development of theories that explain the link between brain function and memory, and in the development of cognitive neuropsychology, a branch of psychology that aims to understand how the structure and function of the brain relates to specific psychological processes


Thirty years earlier, as a PhD student at MIT, Squire had worked alongside a group studying a man known as “H.M.,” one of the most famous patients in medical history. When H.M.—his real name was Henry Molaison, but scientists shrouded his identity throughout his life—was seven years old, he was hit by a bicycle and landed hard on his head. 1.4, 1.5, 1.6 Soon afterward, he developed seizures and started blacking out. At sixteen, he had his first grand mal seizure, the kind that affects the entire brain; soon, he was losing consciousness up to ten times a day. By the time he turned twenty-seven, H.M. was desperate. Anticonvulsive drugs hadn’t helped. He was smart, but couldn’t hold a job. 1.7 He still lived with his parents. H.M. wanted a normal existence. So he sought help from a physician whose tolerance for experimentation outweighed his fear of malpractice. Studies had suggested that an area of the brain called the hippocampus might play a role in seizures. When the doctor proposed cutting into H.M.’s head, lifting up the front portion of his brain, and, with a small straw, sucking out the hippocampus and some surrounding tissue from the interior of his skull, H.M. 1.8, 1.9 gave his consent. The surgery occurred in 1953, and as H.M. healed, his seizures slowed. Almost immediately, however, it became clear that his brain had been radically altered. H.M. knew his name and that his mother was from Ireland. He could remember the 1929 stock market crash and news reports about the invasion of Normandy. But almost everything that came afterward—all the memories, experiences, and struggles from most of the decade before his surgery—had been erased. When a doctor began testing H.M.’s memory by showing him playing cards and lists of numbers, he discovered that H.M. couldn’t retain any new information for more than twenty seconds or so. From the day of his surgery until his death in 2008, every person H.M. met, every song he heard, every room he entered, was a completely fresh experience. His brain was frozen in time. Each day, he was befuddled by the fact that someone could change the television channel by pointing a black rectangle of plastic at the screen. He introduced himself to his doctors and nurses over and over, dozens of times each day. 1.10 “I loved learning about H.M., because memory seemed like such a tangible, exciting way to study the brain,” Squire told me. “I grew up in Ohio, and I can remember, in first grade, my teacher handing everyone crayons, and I started mixing all the colors together to see if it would make black. Why have I kept that memory, but I can’t remember what my teacher looked like? Why does my brain decide that one memory is more important than another?” When Squire received the images of Eugene’s brain, he marveled at how similar it seemed to H.M.’s. There were empty, walnut-sized chunks in the middle of both their heads. Eugene’s memory—just like H.M.’s—had been removed

Of course, Henry didn’t know that. No matter how many times the scientists told him he was famous, he’d always forget. (It was an odd sort of fame: The scientists kept even his first name a closely guarded secret from the outside world and didn’t reveal it until after his death, when it was unveiled in a front-page obituary in this newspaper.) Similarly, Henry didn’t know why he was in a wheelchair that day, in the office at M.I.T., because he didn’t remember badly spraining his ankle a few weeks before.

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