Trouble in Mind

A neuropsychologist muses on brains, books and being happy

HM, the Man with No Memory

Henry Molaison (HM) gave science the ultimate gift: his memory. Over 55 years he became the most studied medical case in history, and on death his brain was dissected into 2000 slices and digitized as a three-dimensional brain map, preserving his tragically unique brain for posterity. Read More

HM's memory

You said he did Crossword puzzles. Could you explain how he could do Crossword puzzles, which is essentially a memory test, with no memory? You said he had no new conscious memories since 1953 and didn't know the current President of the U.S., let alone past ones.

There are many different

There are many different types of memory. A crossword puzzle mostly involves working memory and semantic memory. Working memory tasks usually activate the pre-frontal cortex and a few other brain regions which were intact in H.M. The hippocampus is mainly involved in the encoding of spatial and episodic memory, although it does a lot of other things as well. I guess what I'm trying to say is that it's not correct to say that H.M. had no memory. It would be more correct to say that H.M.'s ability to commit new information to long-term memory was extremely impaired.

There are many different types of memory

Hi James,
Yes, of course you are right. In particular HM's "motor memory" — learning to use his walking frame for example but without being conscious that he ever used it, was intact as was his abuility to repeat 5 digits if not distracted (short term memory) and his "working memory" . But he could only use his working memory (say to work out a mental arithmetic sum) if he were not distracted even for a few seconds. If he were distracted he would forget the information he held in his working memory and that he was meant to be working out the sum. "The man with no memory" is simply a catchy blog title and the way most people think about HM. Indeed in general terms the phrase certainly reflects the HM people interacted with. His conscious global memory impairment was INCREDIBLY dense. In my next blog I will give some more curious facts about the very rare exceptions to his dense global amnesia for famous people who were in the public eye first after HM's surgery. There are numerous book chapters and many thousands of research papers written about the details of HM's memory of course, and the chapters in my books "Fractured Minds" and "Trouble In Mind" are just two that discuss the finer details of his memory disorder in a way that is hopefully readily accessible to the general reader.
Thank you for your comment!

HM and crossword puzzles

The crossword puzzles he did were very simple; designed for a child. If they did have clues regarding "new" information (he would not be able to do them. Basically they just kept him busy and entertained in the moment.

Interesting post

Very nice!

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Jenni Ogden, Ph.D., is a clinical neuropsychologist and author of Trouble in Mind: Stories from a neuropsychologist's casebook, and the text, Fractured Minds.


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