WordNet (r) 3.0 (2006):

engram
    n 1: a postulated biochemical change (presumably in neural
         tissue) that represents a memory [syn: engram, memory
         trace]

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "engram":
   Mnemosyne, affect memory, anterograde memory, archetypal pattern,
   archetype, atavism, collective memory, computer memory,
   disk memory, drum memory, emotional response, father image, image,
   imago, information storage, kinesthetic memory, memory,
   memory bank, memory circuit, memory trace, mind, mneme,
   race memory, recollection, remembrance, screen memory, skill,
   souvenir, tape memory, traumatic trace, unconscious memory,
   verbal response, visual memory