# Engram **Domain:** Neuroscience / Memory **Doc Type:** Scientific Concept Node **Maturity:** Active Experimental Science **Related:** [[Long-Term Memory Substrate]], [[Synaptic Ensemble]], [[Neural Mapping]] --- ## Definition An **engram** is the physical and functional trace through which an experience leaves a persistent effect on a nervous system and can later contribute to memory expression. Contemporary research often studies ensembles of cells and synapses whose activity and plasticity participate in encoding, consolidation, retrieval, and updating. ## Evidentiary boundary An engram is not necessarily a single localized object or complete standalone memory. Memory may depend on distributed changes, systems consolidation, context, and dynamic reactivation.