The plan for H.M.'s brain

Recently, the most famous (and most studied) person in neuroscience died. Science has a nice piece on the planning and post-morten examination of this most famous brain:

[Suzanne] Corkin delivered Cryopaks to his nursing home in Windsor Locks, Connecticut. “They kept them in the freezer so that the moment he died they could wrap his head to preserve the brain,” she says. When Molaison [ie. H.M.] died of respiratory failure at 5:05 p.m. on 8 December 2008, the plan sprang into action. A hearse took his body to Massachusetts General Hospital (MGH) in Charlestown, where researchers began collecting anatomical magnetic resonance imaging (MRI) scans of his brain at about 9 p.m.—and continued until 6 a.m. the next day, when Annese arrived on a red-eye flight from San Diego.

Jacopo Annese, a neuroanatomist at UCSD, is planning on putting H.M.’s whole brain online on his website. But before that happens, he has a rather huge task before him:

Using a microtome, he will slice the brain into very thin sections. “Like prosciutto,” he says, but less than 1/20 the thickness and a lot more fragile. Annese aims to slice the brain whole instead of first cutting it into smaller chunks as is more routinely done. Small chunks are much easier to work with, but the resulting slices are hard to keep in register with one another. Whole-brain slices will keep more of the tissue intact and result in a more faithful reconstruction of the brain, he says. Annese estimates he will end up with about 2600 slices of Molaison’s brain. He and his colleagues will mount some of these, perhaps every 12th one to start, on extra-large glass slides—13 by 18 centimeters—and treat them with a stain that colors cell bodies purple. A camera attached to a microscope will photograph each slice at 20x magnification, sufficient to distinguish different cell types. At that magnification, photographing a single slice will require a mosaic of about 40,000 individual images.

And there is some stress that comes from dealing with such a one-of-a-kind specimen:

But a lot could go wrong. The MRI scans reveal deterioration of the white matter, Annese says, which might make the slices especially delicate and prone to tearing. An even more nightmarish scenario is a cracked brain, he says. Sometimes, a brain will freeze unevenly and break apart—destroying it before it can be sliced. Annese is taking every precaution, but he’s not taking anything for granted. “Cutting will make or break the project,” he says. “But if the brain cracks, I go back to Italy.”


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