The transition from memory retrieval to extinction

Anais da Academia Brasileira de Ciências

Martín Cammarota²  Daniela M. Barros¹  Mónica R.m. Vianna²  Lia R.m. Bevilaqua²  Adriana Coitinho²  Germán Szapiro¹  Luciana A. Izquierdo²  Jorge H. Medina¹  Iván Izquierdo² 

[1] ,Universidade Federal Do Rio Grande Do Sul Departamento de Bioquímica ICSPorto Alegre RS ,Brasil

关键词: memory;    retrieval;    extinction;    reconsolidation;    inhibitory avoidance;    memória;    expressão;    extinção;    reconsolidação;    esquiva inibitória;   

DOI  :  10.1590/S0001-37652004000300011

来源: SciELO

【 摘 要 】

Memory is measured by measuring retrieval. Retrieval is often triggered by the conditioned stimulus (CS); however, as known since Pavlov, presentation of the CS alone generates extinction. One-trial avoidance (IA) is a much used conditioned fear paradigm in which the CS is the safe part of a training apparatus, the unconditioned stimulus (US) is a footshock and the conditioned response is to stay in the safe area. In IA, retrieval is measured without the US, as latency to step-down from the safe area (i.e., a platform). Extinction is installed at the moment of the first unreinforced test session, as clearly shown by the fact that many drugs, including PKA, ERK and protein synthesis inhibitors as well as NMDA receptor antagonists, hinder extinction when infused into the hippocampus or the basolateral amygdala at the moment of the first test session but not later. Some, but not all the molecular systems required for extinction are also activated by retrieval, further endorsing the hypothesis that although retrieval is behaviorally and biochemically necessary for the generation of extinction, this last process constitutes a new learning secondary to the unreinforced expression of the original trace.

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