Henry Molaison, known previously as “Patient HM,” had a memory that lasted only a few minutes as a result of brain surgery conducted in 1953 that was intended to stop his severe epilepsy. HM lived for 55 years after his surgery with severe anterograde memory loss. His working memory and procedural memory were in tact, but where he had trouble was in transferring short-term memories into long-term memories. He and his brain have been thoroughly studied by the scientific community for his condition.
This brain (pictured above) allowed scientists to locate where new memories are formed (the hippocampus), and also allowed scientists to understand that memory really comes in many different forms: learning, long-term, short-term, conscious, unconscious.
This image was shot by Spencer Lowell for a story, “The Art & Science of Slicing up a Human Brain”, featured in Discover magazine in 2010. The brain sits in a plexiglass mold waiting to be embedded in gelatin, frozen, sliced, dyed, mounted, and finally scanned.