Fear & Extinction

Animal Models in Fear & Extinction

Animal research has consistently shown the interplay between the hippocampus and amygdala in fear conditioning. The amygdala facilitates the acquisition of the conditioned fear response to both the conditioned stimulus (CS) and foreground context; the hippocampus facilitates learning acquisition to the background context.

Fear-related extinction evolves when a fear producing CS or context is presented in absence of a US to cause its learned unpairing. Extinction learning reflects a CS-no US fear association (or CR-no fear) association super-imposed on a fear producing CS-fear (or CR-fear) association. Extinction is not equivalent to forgetting; the mere passage of time is not sufficient for extinction to occur. Reexposure to the actual CS without the aversive US is required. (Read more)

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Human Fear Conditioning & Extinction

Human fear conditioning learning and extinction (unpairing CS-US) research has pointed to a role for temporal-phased consolidation processes. These phases were associated by activations of different brain regions. Accordingly, the acquisition phase (i.e. during the delays after pairing trials) was associated with initial reactive cue-dependent autonomic arousal and significant prefrontal activity, as in the midcingulate cortex and anterior insula cortex, and basal ganglia’s caudate nucleus. These structures have previously been associated with autonomic arousal, pain perception, the emotion of fear, and event-related fear conditioning in the human. (Read more)

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