Elsevier

Biological Psychiatry

Volume 76, Issue 4, 15 August 2014, Pages 274-280
Biological Psychiatry

Review
Reconsolidation of Human Memory: Brain Mechanisms and Clinical Relevance

https://doi.org/10.1016/j.biopsych.2014.03.008Get rights and content

The processes of memory formation and storage are complex and highly dynamic. Once memories are consolidated, they are not necessarily fixed but can be changed long after storage. In particular, seemingly stable memories may re-enter an unstable state when they are retrieved, from which they must be re-stabilized during a process known as reconsolidation. During reconsolidation, memories are susceptible to modifications again, thus providing an opportunity to update seemingly stable memories. While initial demonstrations of memory reconsolidation came mainly from animal studies, evidence for reconsolidation in humans is now accumulating as well. Here, we review recent advances in our understanding of human memory reconsolidation. After a summary of findings on the reconsolidation of human fear and episodic memory, we focus particularly on recent neuroimaging data that provide first insights into how reconsolidation processes are implemented in the human brain. Finally, we discuss the implications of memory modifications during reconsolidation for the treatment of mental disorders such as posttraumatic stress disorder and drug addiction.

Section snippets

Memory Reconsolidation: Nothing Is Written in Stone

The idea that memories may re-enter a vulnerable state after their retrieval is not at all new. Already in the 1960s, it was shown that electroconvulsive shock, an amnesic treatment, resulted in memory loss if administered immediately after retrieval or reinstatement of a seemingly robust passive-avoidance memory (7, 8). Similar findings were reported in the following years (9, 10). These data were interpreted as evidence for a distinction between inactive, invulnerable memory traces wired into

Reconsolidation of Human Fear Memory

Based on the findings in rodents demonstrating that conditioned fear memory can be changed when reactivated (17), researchers sought to target the reconsolidation of fear memory in humans. A first study on the reconsolidation of human fear memory (27) capitalized on the well-known role of adrenergic receptors for emotional memory (28). In this study, healthy participants were first fear-conditioned and the fear was reactivated by a single presentation of a conditioned stimulus 24 hours later.

Reconsolidation of Human Episodic Memory

The malleability of episodic memories long after encoding has been widely accepted in cognitive psychology (45, 46). However, the role of reconsolidation processes in the modification of episodic long-term memory traces has been addressed only rather recently. In an elegant set of experiments (47), participants learned a list of objects on day 1. Twenty-four hours later, half of the subjects received a reminder, and then all subjects learned a second list of objects. Memory for the original

Reconsolidation in the Human Brain

How is the reconsolidation of fear or episodic memories represented in the human brain? The first study that addressed this question employed the superior memory for emotional relative to neutral information (62). It is well established that this emotional memory enhancement is owing to arousal-related noradrenergic activity in the amygdala (63, 64), and it has been shown that the administration of the beta-adrenergic receptor antagonist propranolol shortly after learning blocks the enhanced

Changing Memories after Reactivation: Clinical Perspectives and Boundary Conditions

The ability to modify established emotional memories has important implications for the treatment of many mental disorders, including anxiety disorders, such as PTSD, and addiction, as demonstrated by initial clinical studies in the 1960s (73). In PTSD, the strength of trauma memory can be considered the result of the overconsolidation of the memory for the traumatic event due to the action of stress hormones, such as glucocorticoids and noradrenaline, that are released in response to the

Summary

Starting from its rediscovery at the end of the past century, reconsolidation has been the topic of intense scientific inquiry. Animal studies provided important insights into the molecular and cellular basis of reconsolidation (100). Reconsolidation of human memory has by now been demonstrated repeatedly and across different tasks. First evidence points to a potential use of reconsolidation manipulations in the treatment of disorders such as PTSD and addiction and, most recently, neuroimaging

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