The most famous neuroscience patient and test subject died last week, and the researchers who worked with him say they’ll never forget the man who never remembered them. The patient known as H.M. lost the ability to form new memories after he had brain surgery at the age of 27, and studies of his behavior taught researchers basic lessons about how memory and learning work. “He was a very gracious man, very patient, always willing to try these tasks I would give him,” [said Brenda] Milner, a professor of cognitive neuroscience. “And yet every time I walked in the room, it was like we’d never met” [The New York Times].
Henry Gustav Molaison, a Hartford [Connecticut] native, existed in relative obscurity. But as “H.M.,” the name used to disguise his identity, Molaison gained an anonymous sort of fame, a man who had been studied by more than 100 researchers and became a staple of psychology class lectures…. “I’ve been lecturing about him and teaching about him for years and years, decades, and I’ve never known his name” [Hartford Courant], says psychiatrist David Glahn. Molaison died at a Connecticut nursing home on Tuesday at the age of 82, of respiratory failure.
Molaison began having seziures after a childhood bicycle accident, and by the age of 27 they were seriously interfering with his daily life. In 1953 surgeons removed two slices of his brain and cut into a region called the hippocampus–this stopped his seizures, but also gave Molaison a form of amnesia where he could remember events from before the surgery but couldn’t form any new long-term memories.
To the researchers surprise, however, Molaison’s short-term memory was intact and allowed him to hold a thought for about 20 seconds. Studying Molaison also proved that conscious memory is distinct from motor memory, the capacity that allows people to jump on a bike and ride after a hiatus of years. Researchers had Molaison perform a difficult drawing task repeatedly; each time it struck him as an entirely new experience. He had no memory of doing it before. Yet with practice he became proficient. “At one point he said to me, after many of these trials, ‘Huh, this was easier than I thought it would be,’ ” Dr. Milner said [The New York Times].
Even in death, Molaison will continue to help science–his brain is being preserved and shipped to the Brain Observatory at the University of California San Diego. When the famous organ arrives, researchers will undertake a complex, delicate, months-long process of sectioning it into thin slices like deli meat, simultaneously imaging the tissue with different technologies. Ultimately, researchers will be able to examine slices of Molaison’s brain at varying scales, even zooming down to the cellular level in a way similar to how Google Earth can be used [San Diego Union-Tribune]. Researchers will be able to study exactly how Molaison’s brain differed from that of a healthy person, and the public will be able to access all the images on the Brain Observatory’s Web site.
The researchers who worked with Molaison say they wish they could have made him understand what the world learned from his personal tragedy. “I am very indebted to him,” Milner said. “I constantly felt like it was such a shame we couldn’t reward him” because he couldn’t remember from moment to moment. “I would’ve liked to do something for someone whose [sic] done so much” for science [The Scientist].
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