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The Mystery of Memory

Scientist‘s 46-year focus on famous amnesic patient unlocked doors even as it changed their lives

by Ali Benjamin

 

Suzanne Hammond Corkin ’59 met Henry Molaison in 1962, just nine years after he had undergone a targeted lobotomy to cure debilitating epilepsy. The dramatic operation—even the surgeon called it “frankly experimental”—removed much of his hippocampi, his amygdalae and the cortex around his hippocampi. Although his epilepsy abated, it left devastating consequences: Henry could no longer form new memories. From the age of 27, he experienced the world in 30-second increments, forgetting each moment almost as soon as it happened. Over the next four and a half decades, Corkin studied Henry—known in textbooks, journals and the media simply as H.M. Her extensive research greatly expanded scientific understanding of memory and the brain.Suzanne Corkin

 

Beyond the research subject was the human being that was Henry Molaison. Few people knew that person better than Corkin. Even after decades, however, Henry himself never built more than a passing familiarity with her name; he thought perhaps Suzanne Corkin was someone he knew from high school. She documented both her relationship with Henry and her research in a highly regarded book, Permanent Present Tense: The Unforgettable Life of the Amnesic Patient, H.M. (Basic Books, 2013). The Wall Street Journal called it “a remarkable blend of biography, memoir and scientific history,” and Nature called it “a panoramic history of the past 60 years of the neuropsychology of memory… superb.”

 

Here, Corkin, emerita professor of behavioral neuroscience at the Massachusetts Institute of Technology, shares what science learned from Henry, and what it was like working so closely with the world’s most famous amnesic patient.

 

 

Before Henry, we knew little about the complexities of memory. From him we learned that memory and intelligence are not the same thing; he was living proof that you could be intelligent and still have a problem with memory. Second, we learned that the ability to form new memories is localized to a specific part of the brain, the hippocampal complex. Without that region, humans can’t retain new experiences or knowledge. Finally, we learned that there are different types of memories, each residing at different addresses within the brain. That’s why Henry was able to unconsciously acquire new motor skills—he learned to use a walker, for example—even though he could not retain conscious knowledge.

 

From 1966 to 2000, Henry made 50 different trips to the Clinical Research Center at MIT. He was a terrific research subject. His amnesia was pure— totally uncomplicated by other deficits. Plus, Henry somehow knew that these tests would contribute to our understanding of the brain. He loved being a part of research, even if we had to constantly remind him what we were doing.

 

He was also a terrific human being. Henry was a good man—gentle, intelligent, altruistic and endearing. At MIT, we often walked together between the Clinical Research Center and the psychology department. Henry always walked on my outside, cupping my right elbow with his left hand. He wanted to take care of me, when in fact I was nervous about taking proper care of him.

 

By studying his forgetting, we discovered what it is to remember. Memory, we have learned, is a creative act. It requires picking bits and pieces of stored information from many parts of the brain. The brain pulls information from visual, auditory, olfactory, tactile and emotional memory traces, and then weaves these threads together. Every time you retrieve a memory, it’s reshaped so it comes out differently. Henry wasn’t able to reconsolidate and refresh; he told the same stories over and over, using the precise wording and inflection each time.

 

When he died, we had new work to do. Henry and his court-appointed conservator had consented to donating his brain to research. We had spent seven years developing an extremely detailed plan for getting MRI scans of his brain and removing the brain itself. Time was of the essence. When I learned that he had died, I had no time to be sad; I jumped into action. I guess you could say my cortical brain was in control and that I had to put my limbic system—my emotional brain—on hold. There were so many things that could have gone wrong, but thankfully it all went flawlessly. Within a few hours, we were scanning his brain in an MRI machine at Mass General Hospital; that scanning went on for nine hours. Afterward, a neuropathologist skillfully removed his brain and prepared it for future study. Later, when I started to write his obituary, I finally came to grips with the other part of my brain that had been on hold. It was then that I felt the terrible loss of this person with whom I’d had a 46-year bond.

 

The work continues. Henry remains very much a part of my life. His final MRI scans provided a staggering 11 gigabytes of data, enough to fill 16 CDs, and his physical brain was cut into 2,401 slices, each the width of a single human hair. All these data will allow us to learn with certainty which structures had been preserved in Henry’s brain and to map his brain at a cellular level, leading to new revelations about how information is stored. I’m honored to have shared Henry’s story, to have spent so much time with him and to be furthering his contribution. I would do it all over again.

 

 

Ali Benjamin is a freelance writer in western Massachusetts.