Reactivation of recall-induced neurons contributes to remote fear memory attenuation

Abstract

The mechanisms of fear attenuation Surprisingly little is known about how remote fearful memories are stored and attenuated. Khalaf et al. used independent fear memory attenuation paradigms, engram-based tagging techniques, and chemogenetic tools to alter neuronal activity (see the Perspective by Frankland and Josselyn). They found that a discrete subset of neurons within an ensemble is engaged during recall after memory attenuation, which correlated with fear reduction. Memory updating and extinction mechanisms thus likely coexist to make this happen. These findings support the notion that effective memory attenuation is mediated by a rewriting of the original memory trace of fear toward one of safety. Science , this issue p. 1239 ; see also p. 1186