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Distinct contributions of the basolateral amygdala and the medial prefrontal cortex to learning and relearning extinction of context conditioned fear.
Learn Mem. 2008 Sep; 15(9):657-66.LM

Abstract

We studied the roles of the basolateral amygdala (BLA) and the medial prefrontal cortex (mPFC) in learning and relearning to inhibit context conditioned fear (freezing) in extinction. In Experiment 1, pre-extinction BLA infusion of the NMDA receptor (NMDAr) antagonist, ifenprodil, impaired the development and retention of inhibition but post-extinction infusion spared retention. Pre-extinction infusion of the GABA(A) agonist, muscimol, depressed freezing and impaired retention as did post-extinction infusion. In Experiment 2, pre-extinction mPFC infusion of ifenprodil spared the development of inhibition whereas muscimol depressed freezing. Both impaired retention when infused pre- or post-extinction. Thus, the development of inhibition involves NMDAr activation in the BLA, whereas its consolidation involves both NMDAr activation in the mPFC and NMDAr-independent mechanisms in the BLA. In Experiment 3, BLA infusion of ifenprodil impaired relearning and retention of inhibition when infused before but did not impair retention when infused after re-extinction. BLA infusion of muscimol depressed freezing but did not impair retention when infused before or after re-extinction. In Experiment 4, mPFC infusion of ifenprodil impaired relearning when infused before re-extinction, whereas muscimol depressed responses. Both drugs impaired retention when infused into the mPFC before or after re-extinction. Thus, relearning to inhibit fear responses involves NMDAr activation in both the BLA and mPFC and consolidation of the inhibitory memory involves NMDAr activation in the mPFC. However, relearning and consolidation occur in the absence of neuronal activity within the BLA. We propose that NMDAr in the mPFC supports relearning inhibition when the BLA is inactivated.

Authors+Show Affiliations

School of Psychology, The University of New South Wales, Sydney, New South Wales 2052, Australia.No affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18772253

Citation

Laurent, Vincent, and R Frederick Westbrook. "Distinct Contributions of the Basolateral Amygdala and the Medial Prefrontal Cortex to Learning and Relearning Extinction of Context Conditioned Fear." Learning & Memory (Cold Spring Harbor, N.Y.), vol. 15, no. 9, 2008, pp. 657-66.
Laurent V, Westbrook RF. Distinct contributions of the basolateral amygdala and the medial prefrontal cortex to learning and relearning extinction of context conditioned fear. Learn Mem. 2008;15(9):657-66.
Laurent, V., & Westbrook, R. F. (2008). Distinct contributions of the basolateral amygdala and the medial prefrontal cortex to learning and relearning extinction of context conditioned fear. Learning & Memory (Cold Spring Harbor, N.Y.), 15(9), 657-66. https://doi.org/10.1101/lm.1080108
Laurent V, Westbrook RF. Distinct Contributions of the Basolateral Amygdala and the Medial Prefrontal Cortex to Learning and Relearning Extinction of Context Conditioned Fear. Learn Mem. 2008;15(9):657-66. PubMed PMID: 18772253.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Distinct contributions of the basolateral amygdala and the medial prefrontal cortex to learning and relearning extinction of context conditioned fear. AU - Laurent,Vincent, AU - Westbrook,R Frederick, Y1 - 2008/08/26/ PY - 2008/9/6/pubmed PY - 2008/12/31/medline PY - 2008/9/6/entrez SP - 657 EP - 66 JF - Learning & memory (Cold Spring Harbor, N.Y.) JO - Learn Mem VL - 15 IS - 9 N2 - We studied the roles of the basolateral amygdala (BLA) and the medial prefrontal cortex (mPFC) in learning and relearning to inhibit context conditioned fear (freezing) in extinction. In Experiment 1, pre-extinction BLA infusion of the NMDA receptor (NMDAr) antagonist, ifenprodil, impaired the development and retention of inhibition but post-extinction infusion spared retention. Pre-extinction infusion of the GABA(A) agonist, muscimol, depressed freezing and impaired retention as did post-extinction infusion. In Experiment 2, pre-extinction mPFC infusion of ifenprodil spared the development of inhibition whereas muscimol depressed freezing. Both impaired retention when infused pre- or post-extinction. Thus, the development of inhibition involves NMDAr activation in the BLA, whereas its consolidation involves both NMDAr activation in the mPFC and NMDAr-independent mechanisms in the BLA. In Experiment 3, BLA infusion of ifenprodil impaired relearning and retention of inhibition when infused before but did not impair retention when infused after re-extinction. BLA infusion of muscimol depressed freezing but did not impair retention when infused before or after re-extinction. In Experiment 4, mPFC infusion of ifenprodil impaired relearning when infused before re-extinction, whereas muscimol depressed responses. Both drugs impaired retention when infused into the mPFC before or after re-extinction. Thus, relearning to inhibit fear responses involves NMDAr activation in both the BLA and mPFC and consolidation of the inhibitory memory involves NMDAr activation in the mPFC. However, relearning and consolidation occur in the absence of neuronal activity within the BLA. We propose that NMDAr in the mPFC supports relearning inhibition when the BLA is inactivated. SN - 1549-5485 UR - https://www.unboundmedicine.com/medline/citation/18772253/Distinct_contributions_of_the_basolateral_amygdala_and_the_medial_prefrontal_cortex_to_learning_and_relearning_extinction_of_context_conditioned_fear_ DB - PRIME DP - Unbound Medicine ER -