Without a Traceroute

As a neuroscience student, I would be remiss if I allowed the December 2 passing of Henry Molaison (better known as “H.M.”) to pass unremarked, although there’s a certain sad irony inherent in writing a remembrance for a man who could remember nothing. As the world’s most famous amnesiac, H.M. was the subject of hundreds of studies over the course of his lifetime and contributed immeasurably to our understanding of the processes underlying memory.

The story of H.M. will likely be familiar to anyone who’s taken a introductory psychology class in the last 30 years, but I’ve always thought the story of how he became an amnesiac was particularly tragic, and something that’s usually glossed over too quickly in textbooks.

From an early age, Henry suffered from severe seizures that seriously affected his life and prevented him from holding down a job. This being the dark-ages of neurosurgery in the 1950s, the best that doctors could come up with was “Hey, maybe if we cut out a big piece of his brain where the seizures are occurring?”

So that’s what they did. The technical term always used in textbooks is “resectioning”, and doctors resectioned H.M.’s hippocampus, parahippocampal gyrus, and amygdala, comprising a fairly sizable chunk of fairly important grey matter. To their marginal credit, this treatment was effective in combating H.M.’s seizure disorder. In the “oops” column, it also left H.M. with near-total anterograde amnesia—he was unable to create new memories—and some retrograde—loss of past memories—as well.

In the history of neuroscience, many discoveries about the normal functioning of the brain have been made by examining malfunctioning brains, and H.M. was one of the earliest, and most fruitful examples of this. Over the next 50 years of working with H.M., researchers learned (among other things): that the hippocampus is a critical structure in the formation of long-term memory, that proceedural (how to do things) memory is biologically separate from episodic (stuff that happened) memory, that short-term memory is mediated by separate structures as well, and that recall from long-term memory can happen even when storage is impaired.

Depending on your perspective, H.M.’s participation in psychological and neurological studies and the knowledge thereby gained are either a demonstration of science’s ability to salvage some good from a tragedy, or of science’s ability to coldly exploit a catastrophic situation it created itself. I tend to come down on the former side of that equation, but I’ve still always been troubled by the moral issues involved. Not only with the origin of H.M.’s condition, but also by the inability to get informed consent from a person who won’t remember anything he consented to three minutes ago.

H.M.’s story is a reminder of the power of science to elucidate the mysteries of the mind, but it should also remind us that human knowledge is frequently purchased at the cost of human misery.

Rest in peace, Henry. You will be remembered.