Molaison had his hippocampus surgically removed in an attempt to cure his epilepsy. His illness was cured, but the surgery left him with severe amnesia. He retained most of his old memories, but without his hippocampus, he lost his ability to store new ones. Molaison could recall his distant past because the map of those memories had spread throughout his brain. In losing his hippocampus, he lost the ability to make and access new maps and thereby lost his ability to form new memories.
