Health

Scientists Map Brain of World’s Best-Known Amnesiac

There is little question that the most famous patient in all of brain science in the 20th century was Henry Gustav Molaison, who is also known as HM in scientific literature. He suffered from amnesia for more than 50 years and no one knows why. Scientists have studied him for most of his adult life, and recently researchers dissected his brain to figure out exactly which structures contributed to his condition.

HM1

Henry, who died last year of respiratory pneumonia at the age of 82, spent the last twenty-eight years of his life in a nursing home in Connecticut, would often repeat himself with statements like this one below within minutes of each other:

“My daddy’s family came from the South and moved north, they came from Thibodaux Louisiana, and moved north. My mother’s family came from the North and moved south.”

Molaison suffered from dementia that is mysteriously related to surgery performed in 1953. Born in 1926, he had been suffering epileptic seizures since childhood, and at the age of 27, underwent an operation to remove the part of the brain doctors believed were causing the seizures. They took out much of the hippocampus, a horseshoe-shaped structure that plays a major part in long-term memory. It is still not known whether he developed Alzheimer’s disease or vascular dementia, a question which will hopefully be answered with the recent dissection.

The procedure of slicing of HM’s brain was streamed live to the world on a web site run by the Brain Observatory at the University of California in San Diego. A camera photographed each individual slice and the pictures are available on the Web. The procedure is meant to map the human brain in new ways and to better understand special functions such as memory.

Jacopo Annese, director of the Brain Observatory, has compared the exploration of Molaison’s brain to “the search for the formation of colors in an impressionistic painting… If you look at a very small section of the painting up close, you see that many different colors together form the pink streaks that are visible when you step back and look at the whole thing.”

This revolutionary procedure has revealed more about HM’s brain than a high-resolution MRI scan could.

In the words of Suzanne Corkin, professor of behavioral neuroscience at the Massachusetts Institute of Technology, who has studied and worked with Molaison from 1962 until his death:

“The result was that after the surgery, the patient could not form new memories that lasted more than 20 or 30 seconds. The operation did, however, succeed in reducing his seizures, and he paid a high price for that benefit.”

Suzanne Corkin’s first experience with Molaison dates back to 1962 when she was a graduate student at the Montreal Neurological Institute at McGill University. She studied him and two other patients who had undergone brain surgery to treat epilepsy as part of her thesis project. She had no way of knowing then how important her thesis subject would become to scientific research.

Natalie Schenker, a research scientist at the Brain Observatory had this to say:
“He’s taught us a lot about how memories are formed in the brain. Now that he has died and his brain can be looked at anatomically, we can make an even better association between which parts of the brain were responsible for memory formation.”

Molaison was the sad victim of his own circumstances. The surgery to prevent seizures was successfully performed when he was a young man with his whole life ahead of him, but this was truly a battle won and a war lost, for he was never the same afterwards. He returned home to live with his mother and father until their deaths and then moved in with a relative until he was finally placed in the nursing home where he died.

Molaison enjoyed doing crossword puzzles even before the surgery that so devastated his life, as he knew it. According to Corkin, he believed they helped his memory. She said: “He could retrieve any word he knew before the brain surgery but could not learn any words that came into his vocabulary afterward. He spent a lot of time at home doing these puzzles and watching television.”

Molaison’s guardians signed consent forms in 1992 concerning the right to study his brain post mortem. In 2002, Corkin assembled a team of scientists to decide on their course of action upon his death. Researchers have spent the last year preparing for the process of slicing this poor man’s brain. According to Jacopo Annese, “technology allows them to cut the brain at a width of 70 microns, and will yield about 2,600 slices total.”

According to Annese, everyone involved in this revolutionary procedure has been preparing for this scientific moment in time for the last three months and they have gone through several “dress rehearsals” with other brains. Annese further states: “There were 17,000 people watching the live video of the brain cutting and the web site has had more than 3 million hits.”

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  1. Lin Hamilton says:

    So, where is the link to the surgery?