H.M., of blessed memory

Many reports today of the death of Henry Molaison at age 82,  like this from the New York Times.

Over 50 years ago, he underwent brain surgery to treat repeated, strong seizures.  The operation removed part of his hippocampus and left him unable to form any new memories.

From the Times:

For the next 55 years, each time he met a friend, each time he ate a meal, each time he walked in the woods, it was as if for the first time.

At the time, scientists believed memories were stored all over the brain — almost no one imagined that a small bit of the hippocampus could have such a dramatic effect.  Researchers like Dr. Brenda Miller, working with Molaison (known in scientific literature only as H.M.) built up evidence of two types of memory.

Declarative memory is sometimes called the know-what: factual information that’s stored and retrieved.  It’s explicit.  Procedural or tacit memory is the know-how.

As the Times said, Molaison “left a legacy in science that cannot be erased.”

From a post on MindHacks: