Like most famous patients in the history of neuroscience, Henry Molaison—or HM, as he was known among scientists—was famous because his brain was defective. Unlike the other patients, his case was not an accident but the deliberate work of a surgeon. In 1953, a neurosurgeon suctioned out two slivers from brain Henry’s skull, hoping to cure him of epilepsy. The surgery helped the seizures, if not completely, but it made Henry unable to form any new memories.