Amnesia patient H.M., unforgettable to neuroscience, dies at 82

One of the most famous patients in medical science, the man known as H.M., whowas instrumental in showing how the brain's memory systems work, has died.

Henry G. Molaison, 82, died in a nursing home in Connecticut on Tuesday, never knowing how much he had contributed to research.Describedin research during his lifetime only as H.M. to protect his privacy, Molaison had lost the ability to form new memories following an experimental brain operation in 1953 to correct seizures, in which part of his temporal lobe was removed.

"I remember him as extremely gentle, very co-operative, with a good sense of humour," said Brenda Milner, a neuropsychologist at the Montreal Neurological Institute who would visit H.M. to tease out what he was capable of learning.

"He would tell jokes. Of course, he'd tell the same jokes over and over, because he couldn't remember that he'd told them before," she told CBC News on Friday.

Milner, 90, was awarded the Gairdner Award in 2005 to honour her pioneering research in understanding human memory.

Molaison had sharp memories of what happened in his life before the operation.His IQ, personality, sense of identity and reasoning were unaffected, but it was as if he couldn't build up a biography from the time of his operation on, Milner said.

"You don't learn much about a patient if they are just failing in every way," Milner said. "But when you have such a specific kind of loss in the context of perfectly normal thinking abilities otherwise, that is what's so, well, amazing and so instructive."

Over a series of three-day trips to Hartford, Milner gave Molaison several learning tasks. "That's when I had this big breakthrough with a memory learning task," she recalled.

The testing revealed that Molaison was gradually able to master a tricky drawing test involving a mirror, even though he never remembered how many times he had practised it.

"It was absolutely groundbreaking," said Suzanne Corkin, a neuroscientist at the Massachusetts Institute of Technology who worked closely with Molaison, and is a former student of Milner's.

"Before him people didn't know memory could be localized to a specific part of the brain."

Both Corkin and Milner said Molaison was always eager to participate in research.

After his death, scientists took detailed MRI scans of his brain, which will be preserved for future research.