The man who could not make new memories

New memories don’t stay

Key ideaWithout the hippocampus, new memories don’t stay

In 1953, Henry Molaison in the US had most of both hippocampi removed to treat severe epilepsy. His seizures eased, but from then on he could not remember new things that happened to him. As on screen, the new picture (a bicycle) is not written into the links, so a piece of it cannot bring it back. The old pictures above are still there.

Why?He kept many older memories from before the surgery, and could still talk and think. That made it clear for the first time that the hippocampus is where new memories are made. Amazingly, he got better day after day at tracing a star while looking in a mirror. He did not remember practicing, yet his hands remembered. Skills that become second nature are handled somewhere other than the hippocampus.

Go furtherFor years scientific papers called him H.M. instead of his name, which became public after he died in 2008. The psychologist Brenda Milner studied him for decades. Being unable to make new memories is called anterograde amnesia. On screen, the network took the bicycle piece and rolled toward the closest old picture, the beach.