The Hippocampus Patient HM had his hippocampus and adjacent structures of the medial temporal lobe (indicated by the shaded area) surgically removed to stop his epileptic seizures (left). As a result, he could not remember things that happened after the surgery. Henry Molaison (right), better known to the world as patient HM, passed away on December 2, 2008, at the age of 82 at a nursing home near Hartford, Connecticut. Henry participated in countless memory experiments after he became amnesic in 1953, and in so doing made fundamental contributions to our understanding of memory and the brain.