The process of preserving H. M.'s brain is illustrated on the following pages of this article.
This article is a sample from DISCOVER's special Brain issue, available only on newsstands through June 28.
There is an art to removing the brain from a human cadaver. The donor should be lying faceup, and you should stand just behind the crown of the head. Carefully cut through the skin to expose the skull. Using a neurosurgery drill with a guard plate, cut the bone all the way around the head, above the ears. (It might help to pretend you are a barber giving a monk his tonsure.) This process, called fenestration, is more precise than using a saw. Out of respect for the donor, you do not want to damage the brain.
Remove the top of the skull. With a small scalpel, carefully detach the cranial nerves, which emerge from the brain and thread their way through the skull to the face. As you gently lift the brain away from the skull with your left hand, cut the spinal cord with your right, releasing the brain from the skull. Once the organ is loose in your hand, you must be exceedingly gentle: At this stage it has the consistency of a ripe peach. Weigh it, then treat it with fixatives to preserve the tissue.
