Memory reconsolidation and extinction in the crab: Mutual exclusion or coexistence?

Luis María Pérez-Cuesta,Héctor Maldonado

doi:10.1101/lm.1544609

Abstract

A conditioned stimulus (CS) exposure has the ability to induce two qualitatively different mnesic processes: memory reconsolidation and memory extinction. Previous work from our laboratory has shown that upon a single CS presentation the triggering of one or the other process depends on CS duration (short CS exposure triggers reconsolidation, whereas a long CS exposure triggers extinction), both being mutually exclusive processes. Here we show that either process is triggered only after CS offset, ruling out an interaction as the mechanism of this mutual exclusion. Also, we show here for the first time that reconsolidation and extinction can occur simultaneously without interfering with each other if they are serially triggered by respective short and long CS exposures. Thus, we conclude that (1) one single CS presentation triggers one single process, after CS offset, and (2) whether memory reconsolidation and extinction mutually exclude each other or whether they coexist depends only on whether they are triggered by single or multiple CS presentations.

Highlights

It has been proposed that, while mechanistically different, these two processes share an important functional feature: They would both be involved in the acquisition of new information related to previous learning
The finding that extinction consolidation can be individually targeted after reconsolidation is over shows that conditioned stimulus (CS)–US memory reconsolidation and extinction memory consolidation occur in parallel, but they still emerge as two distinct processes
In this final experiment we address the question of when CS–US memory labilization is triggered

Summary

Introduction

It has been proposed that, while mechanistically different, these two processes share an important functional feature: They would both be involved in the acquisition of new information related to previous learning. We present conclusive evidence that CS–US memory is not labilized during a short CS exposure, demonstrating that labilization and reconsolidation as well are triggered after the CS offset This conclusion rules out the possibility of an interaction between reconsolidation and extinction upon a single CS presentation and supports our hypothesis that only after the CS is terminated a switch mechanism operates driving memory to one fate or the other. Given this mutual exclusion, a second important issue is whether either process intrinsically constitutes a constraint on the other or whether they can, under any circumstances, develop in parallel. Throughout this article, memory extinction (or extinction) refers to the process of formation (acquisition) of the new memory (CS–no US), i.e., the extinction memory, leading to

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