Using Extinction-Renewal to Circumvent the Memory Strength Boundary Condition in Fear Memory Reconsolidation.

Tiffany L Campbell,Mallory K Myers,Mitch A Mcdaniel,Jennifer J Quinn,Victoria A Diana,Daniel E Kochli,Mallory E Dunn

doi:10.3390/brainsci11081023

Tiffany L Campbell, Mallory K Myers + Show 5 more

Open Access

https://doi.org/10.3390/brainsci11081023

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Journal: Brain sciences	Publication Date: Jul 31, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: Miami University, Washington College

Abstract

Reconsolidation is a process by which memories are destabilized, updated, and then restabilized. Strong memories are resistant to undergoing reconsolidation. Here, we addressed whether an overtrained fear memory could be made susceptible to reconsolidation by first extinguishing, and then renewing, the memory. Rats were trained with ten tone-footshock pairings, followed by eight days of tone extinction in the training context. The next day, rats were placed into a second context and memory for the tone was renewed/reactivated with a single tone presentation. Immediately following reactivation, rats received an injection of midazolam or vehicle. Rats were then tested for freezing to the tone in a third context. Midazolam had no effect in rats that did not undergo tone extinction, but significantly attenuated freezing to the tone in extinguished rats. Thus, rats that received tone extinction underwent tone memory reconsolidation following its renewal. In a second experiment, we administered the reactivation session and midazolam injections prior to extinction. Midazolam had no effect and rats extinguished at a rate similar to controls. These data suggest that strong emotional memories are capable of updating following weakening of memory expression through extinction.

Highlights

Reconsolidation is a protein synthesis-dependent process by which long-term, stabilized memories may be updated in order to incorporate new information [1,2,3]
The occurrence of memory reconsolidation is demonstrated by a lasting disruption of the memory following protein synthesis inhibition at the time of retrieval, e.g., [5]
The day, rats were tested for fear of the tone in Context B

Summary

Introduction

Reconsolidation is a protein synthesis-dependent process by which long-term, stabilized memories may be updated in order to incorporate new information [1,2,3]. The occurrence of memory reconsolidation is demonstrated by a lasting disruption of the memory following protein synthesis inhibition at the time of retrieval, e.g., [5]. Specific “boundary conditions” have been identified that determines whether a memory undergoes reconsolidation [10,14,15,16]. One such boundary condition is the strength of the memory, with the general consensus being that stronger memories are more resistant to reconsolidation [13,14,15,17,18,19]. This presents a challenge for the translation of reconsolidation-based interventions to psychiatric disorders given that these disorders often involve strong memories, such as those that underlie posttraumatic stress disorder and substance use disorders [19,20]

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