Theoretical locations in the brain that respond to outside stimuli and are then responsible for the storage of memories. The way that memories are stored and replayed in the brain is almost completely unknown, and theories of memories being stored in physical locations tend to be unpopular.

The evidence for engrams mainly comes from experiments conducted by Richard F. Thompson, who experimented on rabbits. He found that by chemically shutting off certain parts of the brain he could make subjects temporarily forget a conditioned response.