Intervention strength does not differentially affect memory reconsolidation of strong memories (original) (raw)
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The mitigating effect of repeated memory reactivations on forgetting
npj Science of Learning, 2018
Memory reactivation is a process whereby cueing or recalling a long-term memory makes it enter a new active and labile state. Substantial evidence suggests that during this state the memory can be updated (e.g., adding information) and can become more vulnerable to disruption (e.g., brain insult). Memory reactivations can also prevent memory decay or forgetting. However, it is unclear whether cueing recall of a feature or component of the memory can benefit retention similarly to promoting recall of the entire memory. We examined this possibility by having participants view a series of neutral images and then randomly assigning them to one of four reactivation groups: control (no reactivation), distractor (reactivation of experimental procedures), component (image category reactivation), and descriptive (effortful description of the images). The experiment also included three retention intervals: 1 h, 9 days, and 28 days. Importantly, the participants received three reactivations equally spaced within their respective retention interval. At the end of the interval, all the participants were given an in-lab free-recall test in which they were asked to write down each image they remembered with as many details as possible. The data revealed that both the participants in the descriptive reactivation and component reactivation groups remembered significantly more than the participants in the control groups, with the effect being most pronounced in the 28-day retention interval condition. These findings suggest that memory reactivation, even component reactivation of a memory, makes memories more resistant to decay.
Neurobiology of Learning and Memory, 2009
Memory reconsolidation is defined as a process in which the retrieval of a previously consolidated memory returns to a labile state which is then subject to stabilization. The reminder is the event that begins with the presentation of the learned cue and triggers the labilization-reconsolidation process. Since the early formulation of the hypothesis, several controversial items have arisen concerning the conditions that define reconsolidation. It is herein proposed that two diagnostic features characterize reconsolidation, namely: the labilization of the reactivated memory and the specificity of the reminder structure. To study this proposal, subjects received two different training sessions on verbal material on Day 1 and Day 2, respectively. Finally, they were tested for the first and second acquired memories on Day 3. It is demonstrated that the human declarative memory fulfills the two requirements that define the process. First, the reactivated memory is impaired by a new learning only when it is given closely after the reminder, revealing that the memory is labilized. Second, the omission of at least one of the reminder's components prevents labilization. Therefore, results show that the new learning fails to produce an amnesic effect on the target memory either when the reminder omits the learned cue or includes the beginning of the reinforcement.
Modification of episodic memories by novel learning: a failed replication study
Background: After reactivation, memories can become unstable and sensitive to modification before they are restored into long-term memory. Using behavioural manipulations, reactivated memories may be disrupted via the mechanism of interference (i.e. novel learning). In a laboratory study, Wichert et al. (2013a) showed that new learning after reactivation changed episodic memory, while new learning alone or reactivation alone did not. Objective: Given the potential clinical application of such a procedure in trauma-focused psychological treatments, such as CBT or EMDR, the aim of this study was to replicate Wichert et al. Method: On Day 1, participants (N = 96) viewed and recalled a series of emotional and non-emotional pictures. Then, participants were randomized to one of four groups. One week later, on Day 8, Group 1 reactivated the previously learned pictures and learned new pictures. To control for specific effects of reactivation or new learning, Group 2 only reactivated the previously learned pictures, and Group 3 only learned new pictures. Group 4 received no reactivation and no new learning. On Day 9, all groups indicated for each picture out of a series whether they had seen it on Day 1. Results: The data were analysed using Bayesian hypothesis testing, which allows for quantifying the evidence in favour of the alternative and the null hypothesis. In general, results showed that Group 1 recognized fewer pictures from Day 1 compared to Groups 2 and 4 on Day 9. However, the expected difference between new learning following reactivation (i.e. Group 1) and new learning alone (i.e. Group 3) was not substantially supported by the data for any of our dependent measures. Conclusions: We replicated some of the findings by Wichert et al., but did not find substantial support for the critical difference between new learning following reactivation and new learning alone.
Memory reactivation effects independent of reconsolidation
Learning & Memory, 2012
Memory reactivation is an important process resulting from reexposure to salient training-related information whereby a memory is brought from an inactive to an active state. Reactivation is the first stage of memory retrieval but can result from the exposure to salient cues without any behavioral output. Such cue-induced reactivation, although frequently used by neuroscientists to study reconsolidation, has seldom been considered as a process in its own right and studied as such. This review presents arguments indicating that memory reactivation has two main consequences: (1) to enhance the accessibility of the target memory and (2) to make the memory malleable. Accordingly, reactivation creates a transient state during which the content of the memory is easily accessible and can be modified and/or updated. As both of these aspects can be observed shortly after memory reactivation, this review emphasizes that reconsolidation is not necessarily required for these processes and calls...
Retrieval of retrained and reconsolidated memories are associated with a distinct neural network
Scientific Reports
Consolidated memories can persist from a single day to years, and persistence is improved by retraining or retrieval-mediated plasticity. One retrieval-based way to strengthen memory is the reconsolidation process. Strengthening occurs simply by the presentation of specific cues associated with the original learning. This enhancement function has a fundamental role in the maintenance of memory relevance in animals everyday life. In the present study, we made a step forward in the identification of brain correlates imprinted by the reconsolidation process studying the long-term neural consequences when the strengthened memory is stable again. To reach such a goal, we compared the retention of pairedassociate memories that went through retraining process or were labilizated-reconsolidated. Using functional magnetic resonance imaging (fMRI), we studied the specific areas activated during retrieval and analyzed the functional connectivity of the whole brain associated with the event-related design. We used Graph Theory tools to analyze the global features of the network. We show that reconsolidated memories imprint a more locally efficient network that is better at exchanging information, compared with memories that were retrained or untreated. For the first time, we report a method to elucidate the neural footprints associated with a relevant function of memory reconsolidation. Consolidated memories can persist from 24 hours to years, depending on the saliency, intensity or emotionality of the information to be remembered 1. It is an accepted idea that the mechanisms responsible for making a memory long-lasting must persist to make the trace resistant to forgetting 2-5. It is possible to modify the persistence of a memory after consolidation simply by retraining or by the presentation of a reminder. A reminder is defined as a group of cues that evoke the original memory trace 6,7. An example of a reminder based way to strengthen memory is the reconsolidation process. That is, when consolidated memories are reactivated by the presentation of specific reminders, the retrieved memory enters in a period of labilization followed by a process of restabilization known as reconsolidation 8-10. Memory reconsolidation has a fundamental role in the maintenance of memory relevance 11. This process is in charge of modifying the strength and/or content of consolidated memories. It has been observed in animal models and in human experiments 12-15. Depending on the treatment used in the
Strengthening a consolidated memory: The key role of the reconsolidation process
The reconsolidation hypothesis posits that the presentation of a specific cue, previously associated with a life event, makes the stored memory pass from a stable to a reactivated state. In this state, memory is again labile and susceptible to different agents, which may either damage or improve the original memory. Such susceptibility decreases over time and leads to a re-stabilization phase known as reconsolidation process. This process has been assigned two biological roles: memory updating, which suggests that destabilization of the original memory allows the integration of new information into the background of the original memory; and memory strengthening, which postulates that the labilization-reconsolidation process strengthens the original memory. The aim of this review is to analyze the strengthening as an improvement obtained only by triggering such process without any other treatment. In our lab, we have demonstrated that when triggering the labilization-reconsolidation process at least once the original memory becomes strengthened and increases its persistence. We have also shown that repeated labilization- reconsolidation processes strengthened the original memory by enlarging its precision, and said reinforced memories were more resistant to interference. Finally, we have shown that the strengthening function is not operative in older memories. We present and discuss both our findings and those of others, trying to reveal the central role of reconsolidation in the modification of stored information.
Several reports have shown that after specific reminders are presented, consolidated memories pass from a stable state to one in which the memory is reactivated. This reactivation implies that memories are labile and susceptible to amnesic agents. This susceptibility decreases over time and leads to a re-stabilization phase usually known as reconsolidation. With respect to the biological role of reconsolidation, two functions have been proposed. First, the reconsolidation process allows new information to be integrated into the background of the original memory; second, it strengthens the original memory. We have previously demonstrated that both of these functions occur in the reconsolidation of human declarative memories. Our paradigm consisted of learning verbal material (lists of five pairs of nonsense syllables) acquired by a training process (L1-training) on Day 1 of our experiment. After this declarative memory is consolidated, it can be made labile by presenting a specific reminder. After this, the memory passes through a subsequent stabilization process. Strengthening creates a new scenario for the reconsolidation process; this function represents a new factor that may transform the dynamic of memories. First, we analyzed whether the repeated labilization-reconsolidation processes maintained the memory for longer periods of time. We showed that at least one labilization-reconsolidation process strengthens a memory via evaluation 5 days after its re-stabilization. We also demonstrated that this effect is not triggered by retrieval only. We then analyzed the way strengthening modified the effect of an amnesic agent that was presented immediately after repeated labilizations. The repeated labilization-reconsolidation processes made the memory more resistant to interference during re-stabilization. Finally, we evaluated whether the effect of strengthening may depend on the age of the memory. We found that the effect of strengthening did depend on the age of the memory. Forgetting may represent a process that weakens the effect of strengthening.
Behavioral reconsolidation interference with episodic memory within-subjects is elusive
Neurobiology of learning and memory, 2018
In studies of behavioral reconsolidation interference, reactivation of a consolidated memory using some form of reminder is followed by the presentation of new information that can cause interference with that memory. Under these conditions, the interference not only impairs retrieval by indirect processes such as cue interference, but supposedly disrupts the original memory trace directly. Almost all studies of behavioral reconsolidation interference in episodic memory in humans have employed between-subjects paradigms, and deduced reminder effects from intrusion errors. Such studies might introduce confounds arising, for example, from differences in retrieval strategies engendered by the pre-test treatments. We therefore set out to examine whether behavioral reconsolidation interference in episodic memory might be demonstrated within-subjects and by direct memory strength rather than intrusion errors. In three separate experiments, we attempted to disrupt reconsolidation of episod...
Determinants to trigger memory reconsolidation: The role of retrieval and updating information
Neurobiology of Learning and Memory, 2017
Pharmacological inhibition of retrieval does not impede memory from undergoing reconsolidation. Memory retrieval has two dissociable components inducing memory expression and memory reconsolidation. Two components of retrieval: the executor and the integrator. The first would be related to the expression of memory, and the second would deal with memory reconsolidation.
Retrieval-induced forgetting and mental imagery
Memory & cognition, 2009
Retrieval has been found to be a potent method for modifying memory that is typically associated with later facilitated memory performance of that information both at short and longer delays (Bjork & Bjork, 1992). Retrieval can be found in numerous memory tasks, such as cued recall, postevent questioning, questionnaires, and surveys collecting personal data. More recently, however, retrievalbased tasks have also been associated with more negative memory-modifying properties. Such negative effects typically occur as a consequence of retrieving other items from memory (see, e.g., Anderson, R. A. Bjork, & E. L. Bjork, 1994). For example, during many everyday memory tasks, one may attempt to retrieve a desired memory from a larger category of related information, such as one's current telephone number from the category of all previously held numbers. So that we may complete this task quickly and efficiently, the related-but-unwanted memories may be pushed out of conscious awareness to prevent them from competing for retrieval and disrupting the successful retrieval of the desired memory. Whereas we may then be able to complete the current processing goal (i.e., the retrieval of the desired memory), the related-but-unwanted memories may remain unavailable for retrieval for some time afterward; that is, if we then wish to retrieve one of those previously unwanted memories, we may find it difficult to do so. This failure to retrieve previously related-but-unwanted memories is known as retrieval-induced forgetting. Both the facilitatory effects of retrieval and its negative consequences are typically examined using the retrieval practice paradigm. In a retrieval practice task, participants study categories of related information (e.g., fruitapple, fruit-banana; sport-golf, sport-hockey) and are then prompted to retrieve a subset of items from a subset of categories using guided retrieval practice (e.g., fruit-ap_____). This selective retrieval typically produces three types of items: practiced items from practiced categories (i.e., fruitapple), unpracticed items from practiced categories (i.e., fruit-banana), and items from unpracticed categories (i.e., sports). In the final task, the processing goal shifts from selective to global retrieval, and participants' memory is tested for all items from all categories, typically using either cued or free recall. The retrieval practice paradigm typically produces two patterns of recall: (1) Memory performance for practiced items from practiced categories (i.e., Rp1 items) is facilitated, whereas that for unpracticed category items (i.e., Nrp items) is not; and (2) memory performance for unpracticed items from practiced categories (i.e., Rp2 items) is impaired, relative to that for Nrp items (i.e., retrievalinduced forgetting). Such effects have also been found in impression formation (