From aversive associations to defensive programs: experience-dependent synaptic modifications in the central amygdala

• Published in: Trends in neurosciences (Regular ed.) 2023-09, Vol.46 (9), p.701-711
• Main Authors: Penzo, Mario A., Moscarello, Justin M.
• Format: Article
• Language: English
• Subjects: active avoidance; Affect; Central Amygdaloid Nucleus; experience-dependent synaptic plasticity; Fear - physiology; fear circuits; fear conditioning; Humans; Memory - physiology; memory expression; Neuronal Plasticity - physiology; somatostatin
• ISSN: 0166-2236; 1878-108X; 1878-108X
• DOI: 10.1016/j.tins.2023.06.006

Experience-dependent synaptic plasticity in the central nucleus of the amygdala (CeA) takes on different forms depending on whether animals are trained using fear conditioning or active avoidance tasks.Such dynamic patterns of CeA plasticity determine the selection of appropriate defensive responses to a given conditioned stimulus (CS) by biasing the winner-takes-all competition between mutually inhibitory CeA microcircuits.We propose that experience-dependent synaptic plasticity in the CeA has a specific role in the expression of CS–unconditioned stimulus associations and that it plays no role in the storage or reactivation of such memories. Plasticity elicited by fear conditioning (FC) is thought to support the storage of aversive associative memories. Although work over the past decade has revealed FC-induced plasticity beyond canonical sites in the basolateral complex of the amygdala (BLA), it is not known whether modifications across distributed circuits make equivalent or distinct contributions to aversive memory. Here, we review evidence demonstrating that experience-dependent synaptic plasticity in the central nucleus of the amygdala (CeA) has a circumscribed role in memory expression per se, guiding the selection of defensive programs in response to acquired threats. We argue that the CeA may be a key example of a broader phenomenon by which synaptic plasticity at specific nodes of a distributed network makes a complementary contribution to distinct memory processes. Plasticity elicited by fear conditioning (FC) is thought to support the storage of aversive associative memories. Although work over the past decade has revealed FC-induced plasticity beyond canonical sites in the basolateral complex of the amygdala (BLA), it is not known whether modifications across distributed circuits make equivalent or distinct contributions to aversive memory. Here, we review evidence demonstrating that experience-dependent synaptic plasticity in the central nucleus of the amygdala (CeA) has a circumscribed role in memory expression per se, guiding the selection of defensive programs in response to acquired threats. We argue that the CeA may be a key example of a broader phenomenon by which synaptic plasticity at specific nodes of a distributed network makes a complementary contribution to distinct memory processes.