The neurocircuitry of remote cued fear memory

Abstract

Memories of threatening, fear-evoking events can persist even over a lifetime. While fear memory is widely considered to be a highly persistent and durable form of memory, its circuits are not. This article reviews the dynamic temporal representation of remote fear memory in the brain, at the level of local circuits and distributed networks. Data from the study of Pavlovian cued fear conditioning suggests memory retrieval remains amygdala-dependent, even over protracted time scales, all the while interconnected cortical and subcortical circuits are newly recruited and progressively reorganized. A deeper understanding into how the neurocircuitry of cued fear memory reorganizes with the passage of time will advance our ongoing search for the elusive physical changes representing fear memories in the brain. Considering that persistent, pathological fear memories are a hallmark feature of post-traumatic stress disorder (PTSD), the behavioral and circuit-level study of remote cued fear memory retrieval adds a key element towards a systems understanding of PTSD.

Keywords: Anterior cingulate; Auditory cortex; Bed nucleus of the stria terminalis; Contextual fear conditioning; Engram; Generalization; Hippocampus; Incubation; Infralimbic; Multiple trace theory; Paraventricular nucleus of the thalamus; Post-traumatic stress disorder; Prelimbic; Retrospenial; Systems consolidation; Thalamus; Threat conditioning; Threat memory.