Sections of H.M.'s brain (Photo: Jacopo Annese)
Henry Molaison might well have been the most studied patient in the history of neuroscience. At the age of 27, he underwent brain surgery in an attempt to deal the with the debilitating seizures he had experienced since childhood. The operation was a success — the seizures quieted down — but it also left Molaison with permanent amnesia. Because of his unusual condition, he went on to participate in hundreds of studies on human memory and behaviour. And each time, he was referred to only as H.M.
Molaison died in 2008 at the age of 92. Now his brain, which he donated to science, has been sliced into 2,401 paper-thin slices, scanned and uploaded to create The Atlas of H.M.'s Brain.
The project, reported this week in Nature Communications, was spearheaded by Jacopo Annese, a neuroanatomist who runs The Brain Observatory at the University of California at San Diego. On the one-year anniversary of Molaison's death, National Geographic reports, Annese began the 53-hour process of slicing the brain into 0.07 mm-thick sections. Here's what that process looks like:
Each slice was photographed with a high-resolution camera, and eventually uploaded into the interactive atlas, which uses a Google Maps-like interface to allow you pan and zoom around on each image. You can get a look the incredible detail visible in each slice in this online teaser (the full atlas is being made available to any researcher interested in collaboration).
As Annese and his co-authors point out in Nature Communications, the first article on H.M. was one of the most widely cited articles in all of medical literature. Although Molaison couldn't encode any new memories, his general intelligence was intact. He was also able to learn new motor skills, like the ability to draw a figure by looking at its mirror reflection. Over the years, studies of H.M. revolutionized our understanding of memory and learning, and helped birth the field of cognitive neuroscience. Annese's team hopes that their Atlas will lead to a whole new round of discoveries.
For more on the story of Molaison and his extraordinary brain, see the book Permanent Present Tense by Susan Corkin, the researcher who worked with H.M. for decades, and this feature in Esquire by the grandson of Dr. William Beecher Scoville, who performed the fateful surgery.