Synaptic Potentiation of Engram cells is Necessary and Sufficient for Context Fear Memory

Abstract

The nature and distribution of the synaptic changes that underlie memory are not well understood. We examined the synaptic plasticity behind context fear conditioning and found that learning produced synaptic potentiation specifically onto engram neurons in the basolateral amygdala. This potentiation lasted at least 7 days, was reversed by extinction, and its disruption impaired memory recall. High frequency optogenetic stimulation of the CS and US-activated ensembles, or biochemical induction of synaptic potentiation in US-responsive neurons alone, was sufficient to produce a context fear association without prior associative training. These results suggest that plasticity of CS inputs onto US-responsive amygdala neurons underlies memory formation and is necessary and sufficient to establish context fear associations.