n. the hypothetical memory trace that is stored in the brain. The nature of the engram, in terms of the exact physiological changes that occur to encode a memory, is as yet unknown. The term was introduced by German biologist Richard Semon (1859–1918) in the early 1900s and was popularized by Karl S. Lashley in his 1950 paper “In Search of the Engram.” Also called mneme; mnemonic trace; neurogram.