The patient who transformed the science of memory
Suzanne Corkin was a graduate student at McGill University when she met a young man named Henry Molaison in 1962. She spent several days giving him memory tests as she gathered data for her PhD thesis. But each day she had to reintroduce herself, as Molaison had almost completely lost the ability to form new memories.
Nine years earlier, Molaison had undergone an experimental surgery that doctors hoped would help control his frequent epileptic seizures: a structure known as the hippocampus was removed from both sides of his brain.
Soon after the surgery, Molaison’s doctors realized that the procedure had had a dramatic and unintended consequence. From then on, he would live his life only in the moment, unable to remember what he had for lunch, whom he saw the previous day, or what they had talked about. This tragic loss turned him into one of the most important patients in the history of neuroscience. His case answered more questions about how memory works than the entire previous century of research, writes Corkin, a professor emerita of neuroscience, in her new book, Permanent Present Tense: The Unforgettable Life of the Amnesic Patient, H. M.
Molaison was known as H. M. in scientific papers, but his identity was revealed after his death. “He was a hero,” Corkin says. “He was someone who had something really awful happen to him, and in spite of this, he made a huge contribution.”
In her book, Corkin hopes to shed light on the person behind the studies. “I don’t want people to think of him as just a lesion and a bunch of test scores,” she says. “He had a sense of self, he had values, and he had a wonderful sense of humor.” For example, she recalls, when Molaison was talking with a member of her lab, he summed up his testing experience this way: “It’s a funny thing—you just live and learn. I’m living, and you’re learning.”
Initial studies by Corkin’s graduate-school advisor, Brenda Milner, supported the hypothesis that long- and short-term memories are formed by different processes and in different regions of the brain. Later studies with Molaison helped scientists to clarify the distinction between two types of long-term memory now known as declarative and nondeclarative. Declarative (or explicit) memory refers to recall of specific facts or experiences. Molaison had lost the ability to form that type of memory, although he could recall some declarative memories from before his surgery. But he was still able to form new nondeclarative memories, including learning motor skills such as how to use a walker.
Molaison died in 2008, at age 82. In accordance with his will, his brain was removed and preserved. One year later, scientists at the University of California at San Diego sliced the brain into 2,401 slices, each as thin as a human hair. A live stream of the three-day process was viewed more than three million times.
“He is so much more famous than all of the scientists who studied him put together,” Corkin says. “He revolutionized the science of memory. We look at memory now in a totally different way.”
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