Question: What's a hippocampus, and what's it to you?
Answer: In anatomy, a hippocampus (HIP-o-KAM-pus) is a dollop of gray matter buried deep in the brain that forms the floor of one of the brain's cavities, or ventricles.
The name goes back to the Greek words meaning "sea horse" or "sea monster." The curving hippocampus looks a little like a sea horse. People normally have two of them.
The hippocampus is a key part of the brain's wiring for forming long-term memories, encoding or processing them and distributing them throughout the brain for more-or-less permanent storage. (Short-term or working memory, in contrast, lasts briefly if not converted into long-term memory. That's why you often forget a telephone number after a few minutes.)
Neuropsychologist Paul Broks says in his book, "Into the Silent Land: Travels in Neuropsychology," "To the extent that each of us is the sum of our memories, the hippocampus is the instrument by means of which we assemble ourselves."
Sometimes the hippocampus is removed (a hippocampectomy) to treat epileptic seizures or other neurological conditions. It can also be damaged or destroyed by trauma or disease.
Broks says that people who lose the function of both of their hippocampi suffer profound long-term memory loss. They are left with only short-term memory.