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Experimentelle Beiträge zur Lehre vom Gedächtnis
... In the memory literature, effects of new learning on previously learned material are commonly known as "retroactive interference" (RI) effects (McGeoch & McDonald, 1931;Müller & Pilzecker, 1900;Osgood, 1948). In a typical RI study, participants in the experimental group learn a list of paired associations A-B (between syllables, nouns, or other materials) and then another list where the first members of each pair are associated with new stimuli (A-C). ...
... A central issue when it comes to the fate of a memory trace over time is consolidation. Already Müller and Pilzecker (1900) recognised that memories may need to be consolidated during an "idle mind state" following learning; the detrimental effect of a second list on the recall of a first may simply be due to the lack of opportunity for such a consolidation (see also Dewar et al., 2007, for a summary of Müller & Pilzecker's insights). Indeed, memory consolidation that occurs over time with a central role of sleep and rest (Dewar et al., 2012;Inostroza & Born, 2013) is now thought to be central for the transition of detailed, but short-lived episodic memories into more stable and durable, mostly semantic memories (Nadel et al., 2012;Squire et al., 2015). ...
... In fact, some RI studies found that consolidated material is less susceptible, if at all, to interference from subsequent learning of new information than fresh, unconsolidated knowledge is (e.g., Ellenbogen et al., 2006;Landauer, 1974). In general, it is assumed that the more time a memory has to consolidate, the less it will suffer from subsequent interfering tasks (see Müller & Pilzecker, 1900, for the original formulation of this argument). Whether this is really the case is still being debated (see "General discussion," and Wixted, 2004, for a comprehensive discussion of the role of consolidation in RI). ...
Anecdotal evidence suggests that learning a new foreign language (FL) makes you forget previously learned FLs. To seek empirical evidence for this claim, we tested whether learning words in a previously unknown L3 hampers subsequent retrieval of their L2 translation equivalents. In two experiments, Dutch native speakers with knowledge of English (L2), but not Spanish (L3), first completed an English vocabulary test, based on which 46 participant-specific, known English words were chosen. Half of those were then learned in Spanish. Finally, participants' memory for all 46 English words was probed again in a picture naming task. In Experiment 1, all tests took place within one session. In Experiment 2, we separated the English pre-test from Spanish learning by a day and manipulated the timing of the English post-test (immediately after learning vs. one day later). By separating the post-test from Spanish learning, we asked whether consolidation of the new Spanish words would increase their interference strength. We found significant main effects of interference in naming latencies and accuracy: Participants speeded up less and were less accurate to recall words in English for which they had learned Spanish translations, compared to words for which they had not. Consolidation time did not significantly affect these interference effects. Thus, learning a new language indeed comes at the cost of subsequent retrieval ability in other FLs. Such interference effects set in immediately after learning and do not need time to emerge, even when the other FL has been known for a long time.
... The concept of memory consolidation originated from an unexpected observation made by Müller and Pilzecker (1900). Subjects tasked with learning lists of nonsensical syllable pairs reported experiencing involuntary and intrusive mental rehearsal of the paired associates in between training sessions. ...
... Subjects tasked with learning lists of nonsensical syllable pairs reported experiencing involuntary and intrusive mental rehearsal of the paired associates in between training sessions. This led Müller and Pilzecker (1900) to speculate that such post-learning mental rehearsal might serve to reinforce the associations between syllables. Supporting this idea, they found that recall of a recently learned list of syllables was impaired when subjects learned other material shortly after the first learning. ...
... While spontaneous intrusive recollections are particularly prevalent among subjects afflicted with post-traumatic stress or major depressive disorder, "normal" subjects experience them too (Reynolds and Brewin, 1998). In fact, you will recall that Müller and Pilzecker (1900) were led to the concept of memory consolidation because some of their subjects reported experiencing involuntary mental rehearsal of material to be learned. ...
Emotionally arousing experiences are better remembered than neutral ones, highlighting that memory consolidation differentially promotes retention of experiences depending on their survival value. This paper reviews evidence indicating that the basolateral amygdala (BLA) mediates the facilitating influence of emotions on memory through multiple mechanisms. Emotionally arousing events, in part by triggering the release of stress hormones, cause a long-lasting enhancement in the firing rate and synchrony of BLA neurons. BLA oscillations, particularly gamma, play an important role in synchronizing the activity of BLA neurons. In addition, BLA synapses are endowed with a unique property, an elevated post-synaptic expression of NMDA receptors. As a result, the synchronized gamma-related recruitment of BLA neurons facilitates synaptic plasticity at other inputs converging on the same target neurons. Given that emotional experiences are spontaneously remembered during wake and sleep, and that REM sleep is favorable to the consolidation of emotional memories, we propose a synthesis for the various lines of evidence mentioned above: gamma-related synchronized firing of BLA cells potentiates synapses between cortical neurons that were recruited during an emotional experience, either by tagging these cells for subsequent reactivation or by enhancing the effects of reactivation itself.
... Theories about the processes underlying the sleep benefit in episodic memory have been strongly influenced by the seminal work of Müller and Pilzecker (1900). In a series of studies, these authors investigated learning and forgetting of nonsense syllables. ...
... The purpose of this analysis is to provide more specific and detailed information on often used verbal learning material. Single words and word pairs have been targets of experimental research on episodic memory for more than a century (e.g., Ebbinghaus, 1885;Müller & Pilzecker, 1900) and continue to be used frequently in research on sleep and memory until today (e.g., Diekelmann et al., 2009;Klinzing et al., 2019). Note that we excluded the moderator variable "emotionality" in this subgroup analysis because only one category (neutral) contained more than one effect size. ...
People recall more information after sleep than after an equally long period of wakefulness. This sleep benefit in episodic memory has been documented in almost a century of research. However, an integrative review of hypothesized underlying processes, a comprehensive quantification of the benefit, and a systematic investigation of potential moderators has been missing so far. Here, we address these issues by analyzing 823 effect sizes from 271 independent samples that were reported in 177 articles published between 1967 and 2019. Using multilevel metaregressions with robust variance estimates, we found a moderate overall sleep benefit in episodic memory (g = 0.44). Moderator analyses revealed four important findings: First, the sleep benefit is larger when stimuli are studied multiple times instead of just once. Second, for word materials, the effect size depends on the retrieval procedure: It is largest in free recall, followed by cued recall and recognition tasks. Third, the sleep benefit is stronger in pre-post difference measures of retention than in delayed memory tests. Fourth, sleep benefits are larger for natural sleep and nighttime naps than for alternative sleep study designs (e.g., slow-wave sleep; SWS-deprived sleep, daytime naps). Although there was no obvious evidence for selective reporting, it is a potential threat to the validity of the results. When accounting for selective reporting bias, the overall effect of sleep on episodic memory is reduced but still significant (g = 0.28). We argue that our results support an integrative, multicausal theoretical account of sleep-induced episodic memory benefits and provide guidance to increase their replicability. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
... As previously mentioned, memory consolidation entails the stabilization of newly acquired information into long-term memory 44 . To address the role of the CLA in this memory process, we trained two groups of mice and, immediately after training, infused their CLA with either a Veh or Lido solution. ...
The claustrum is a brain structure that remains shrouded in mystery due to the limited understanding of its cellular structure, neural pathways, functionality and physiological aspects. Significant research has unveiled connections spanning from the claustrum to the entire cortex as well as subcortical areas. This widespread connectivity has led to speculations of its role in integrating information from different brain regions, possibly contributing to processes such as attention, consciousness, learning and memory. Our working hypothesis posits that claustrum neural activity contributes to the acquisition, consolidation and reconsolidation of long-term memories in mice. We found evidence in CF-1 mice of a decline in behavioral performance in an inhibitory avoidance task due to intra-claustral administration of 2% lidocaine immediately after a training session or memory recall. Nevertheless, this does not seem to be the case for the acquisition or retrieval of this type of memory, although its neural activity is significantly increased after training, evaluated through c-Fos expression. Moreover, inhibition of the claustrum’s synaptic activity appears to impair the consolidation but not acquisition or retrieval of an unconditioned memory formed in a nose-poke habituation task.
... Memory interference-i.e. presentation of information that interferes with the retention of the to-be-remembered information [65,66]-is another phenomenon that could provide information on the reconstructive nature of memory. Thus, it would be useful to extend this line of research to these memory errors to further examine bees' constructive memory. ...
The view that human memory is constructive implies that recollections are not necessarily an accurate reproduction of past events. An approach to study this constructive nature of memory is by examining memory errors. In this regard, conjunction errors—i.e. incorrect recollection of new stimuli integrated by components from two previously studied stimuli—have attracted important attention in human memory research. Do animals other than humans make conjunction errors? To investigate this issue, a choice task in which training was not involved was used. Bees experienced two to-be-remembered stimuli. At the test, they were presented with four stimuli: one of the original items (i.e. old), an item made by combining two features of the original items (i.e. conjunction), an item containing a previously presented feature and a new one (i.e. feature), and an item integrated solely by new features (i.e. new). Bumblebees remembered the old items. Importantly, when making memory errors, bumblebees selected conjunction and feature lures more often than new items. These results indicate that bumblebees, like humans, spontaneously make memory conjunction errors and suggest that invertebrates’ memories might also be constructive in nature. I suggest that focusing on memory errors is a solid avenue to investigate episodic (like) memory in animals.
This article is part of the theme issue ‘Elements of episodic memory: lessons from 40 years of research’.
... Whatever the cause, things which could not be recalled on the spot are easily co-ordinated the next day, and time itself, which is generally accounted one of the causes of forgetfulness, as to strengthen the memory." (Quintilian, translated by Butler, 1925) The term "consolidation" was originally proposed more than a century ago to describe the strengthening of memories over time, but without regard to sleep (Müller and Pilzecher, 1900). The first quantitative evidence that sleep slowed or prevented forgetting was shown in a verbal memory task where subjects memorized lists of nonsense syllable-pairs and then were tested for recall at different latencies spent either awake or asleep ( Figure 1) (Jenkins and Dallenbach, 1924). ...
Epilepsy is a complex, multifaceted disease that affects patients in several ways in addition to seizures, including psychological, social, and quality of life issues, but epilepsy is also known to interact with sleep. Seizures often occur at the boundary between sleep and wake, patients with epilepsy often experience disrupted sleep, and the rate of inter-ictal epileptiform discharges increases during non-REM sleep. The Network Theory of Epilepsy did not address a role for sleep, but recent emphasis on the interaction between epilepsy and sleep suggests that post-seizure sleep may also be involved in the process by which seizures arise and become more severe with time (“epileptogenesis”) by co-opting processes related to the formation of long-term memories. While it is generally acknowledged that recurrent seizures arise from the aberrant function of neural circuits, it is possible that the progression of epilepsy is aided by normal, physiological function of neural circuits during sleep that are driven by pathological signals. Studies recording multiple, single neurons prior to spontaneous seizures have shown that neural assemblies activated prior to the start of seizures were reactivated during post-seizure sleep, similar to the reactivation of behavioral neural assemblies, which is thought to be involved in the formation of long-term memories, a process known as Memory Consolidation. The reactivation of seizure-related neural assemblies during sleep was thus described as being a component of Seizure-Related Consolidation (SRC). These results further suggest that SRC may viewed as a network-related aspect of epilepsy, even in those seizures that have anatomically restricted neuroanatomical origins. As suggested by the Network Theory of Epilepsy as a means of interfering with ictogenesis, therapies that interfered with SRC may provide some anti-epileptogenic therapeutic benefit, even if the interference targeted structures that were not involved originally in the seizure. Here, we show how the Network Theory of Epilepsy can be expanded to include neural plasticity mechanisms associated with learning by providing an overview of Memory Consolidation, the mechanisms thought to underlie MC, their relation to Seizure-Related Consolidation, and suggesting novel, anti-epileptogenic therapies targeting interference with network activation in epilepsy following seizures during post-seizure sleep.
... This could be attributed to the additional cognitive resources required for the integration process in encoding tasks, with the excessive activation of the dorsolateral prefrontal cortex leading to an irrational distribution of resources and consequently weakening memory capacity. Furthermore, Research has shown that interference and inhibition are the two main factors leading to forgetting 30 . In paired association learning, participants may initially learn a set of stimulus response word pairs, and then during testing, they may www.nature.com/scientificreports/ ...
Episodic memory is essential for forming and retaining personal experiences, representing a fundamental aspect of human cognition. Traditional studies of episodic memory have typically used static analysis methods, viewing the brain as an unchanging entity and overlooking its dynamic properties over time. In this study, we utilized dynamic functional connectivity analysis on fMRI data from healthy adults performing an episodic memory task. We quantified integration and recruitment metrics and examined their correlation with memory performance using Pearson correlation. During encoding, integration across the entire brain, especially within the frontoparietal subnetwork, was significantly correlated with memory performance. During retrieval, recruitment becomes significantly associated with memory performance in visual subnetwork, somatomotor subnetwork, and ventral attention subnetwork. At the nodal level, a significant negative correlation was observed between memory scores and integration of the anterior cingulate gyrus, precentral gyrus, and inferior frontal gyrus within the frontoparietal network during encoding task. During retrieval task, a significant negative correlation was found between memory scores and recruitment in the left progranular cortex and right transverse gyral ventral, whereas positive correlations were seen in the right posterior inferior temporal, left middle temporal, right frontal operculum, and left operculum nodes. Moreover, the dynamic reconfiguration of the functional network was predictive of predict memory performance, as demonstrated by a significant correlation between actual and predicted memory scores. These findings advance our understanding network mechanisms underlying memory processes and developing intervention approaches for memory-related disorders as they shed light on critical factors involved in cognitive processes and provide a deeper understanding of the underlying mechanisms driving cognitive function.
... During much of the 20th century, the study of the neurophysiology of memory has focused on understanding how memories are formed or stored, a research field in which the consolidation framework has dominated the research agenda (Squire, Genzel, Wixted, & Morris, 2015). Memory consolidation refers to the time-dependent stabilization process that results in the permanent storage of recently acquired information (McGaugh, 1966;Müller & Pilzecker, 1900). According to this view, the synthesis of new proteins plays a pivotal role in memory storage because it is RETRIEVAL FAILURE 4 required to induce enduring changes in the strength of synaptic connections between neurons that support long-term memory storage (Kandel, 2001). ...
A canonical view in the neuroscience of learning and memory literature is that failures in memory expression reflect storage failures, and hence amnesic manipulations following training or following memory reactivation can permanently erase memory traces. In this review, we analyse extant literatures from the learning and memory domains suggesting that most if not all of these memory deficits can be restored with the appropriate retrieval cues. We content that all manipulations conducted immediately after training or following memory reactivation result in new learning, which is highly dependent on retrieval cues for memory expression. Thus, although acquisition and storage mechanisms are important, memory retrieval is a critical component of memory performance, with numerous findings from behavioural and neurobiological studies all converging on this general notion. These conclusions invite a rethinking of the learning and memory literatures and provide new avenues for research.
... Therefore, it would be highly desirable to develop methods to prevent the return of fear. Given that consolidation processes are crucial for long-term memory expression [6][7][8] , reinforcing the consolidation of the extinction memory may be one promising avenue 9 . ...
Even after successful extinction, conditioned fear can return. Strengthening the consolidation of the fear-inhibitory safety memory formed during extinction is one way to counteract return of fear. In a previous study, we found that post-extinction L-DOPA administration improved extinction memory retrieval 24 h later. Furthermore, spontaneous post-extinction reactivations of a neural activation pattern evoked in the ventromedial prefrontal cortex (vmPFC) during extinction predicted extinction memory retrieval, L-DOPA increased the number of these reactivations, and this mediated the effect of L-DOPA on extinction memory retrieval. Here, we conducted a preregistered replication study of this work in healthy male participants. We confirm that spontaneous post-extinction vmPFC reactivations predict extinction memory retrieval. This predictive effect, however, was only observed 90 min after extinction, and was not statistically significant at 45 min as in the discovery study. In contrast to our previous study, we find no evidence that L-DOPA administration significantly enhances retrieval and that this is mediated by enhancement of the number of vmPFC reactivations. However, additional non-preregistered analyses reveal a beneficial effect of L-DOPA on extinction retrieval when controlling for the trait-like stable baseline levels of salivary alpha-amylase enzymatic activity. Further, trait salivary alpha-amylase negatively predicts retrieval, and this effect is reduced by L-DOPA treatment. Importantly, the latter findings result from non-preregistered analyses and thus further investigation is needed.
... The idea of memory consolidation dates back to 1900, when Müller and Pilzecker proposed the preservation-consolidation hypothesis of memory (Müller and Pilzecker, 1900). Their proposal arose after noting the effects of interference on human memory, leading them to think of memory as having two phases: a first phase that could be easily interfered with and disrupted, and a second phase that was fixed. ...
... Classic theories of memory formation, including Müller and Pilzecker's (1900) consolidation model and Atkinson and Shiffrin's (1968) memory model, have been applied to motor skill learning to describe processes of motor memory formation and stabilization. These models suggest that memory development occurs in a series of stages, during which encoded representations are briefly stored in short-term memory and then progressively strengthened, or consolidated, over time to a more stable state in the long-term memory [1][2][3]. More recently, it has been theorized that consolidated memories can be updated to adjust to new contexts or demands through processes of reconsolidation [4][5][6][7]. ...
Motor memories can be strengthened through online practice and offline consolidation. Offline consolidation involves the stabilization of memory traces in post-practice periods. Following initial consolidation of a motor memory, subsequent practice of the motor skill can lead to reactivation and reconsolidation of the memory trace. The length of motor memory reactivation may influence motor learning outcomes; for example, brief, as opposed to long, practice of a previously learned motor skill appears to optimize intermanual transfer in healthy young adults. However, the influence of aging on reactivation-based motor learning has been scarcely explored. Here, the effects of brief and long motor memory reactivation schedules on the retention and intermanual transfer of a visuomotor tracing task are explored in healthy older adults. Forty older adults practiced a virtual star-tracing task either three (“brief reactivation”) or ten (“long reactivation”) times per session over a two-week period. Comparison with a previously reported group of younger adults revealed significant age-related differences in the effect of the motor memory reactivation schedule on the intermanual transfer of the motor task. In older adults, unlike younger adults, no significant between-group differences were found by practice condition in the speed, accuracy, or skill of intermanual task transfer. That is, motor task transfer in healthy younger, but not older, adults appears to benefit from brief memory reactivation. These results support the use of age-specific motor training approaches and may inform motor practice scheduling, with possible implications for physical rehabilitation, sport, and music.
... Subsequent studies by others (e.g. Müller and Pilzecker, 1900;Semon, 1921;Bartlett, 1932) challenged or built on Ebbinghaus' findings, yielding important insights such as the discovery that memory is largely reconstructive and often unreliable. Then, there came a de facto hiatus in memory studies, a logical consequence of the behaviorist dismissal of memory as an incoherent notion (Delaney and Austin, 1998), eclipsed by the appeal of the stimulus-response-reinforcement mechanism. ...
1 Introduction At first glance, the relationship between attention and memory may seem obvious beyond the need for any further argument. It just stands to reason that we commit to memory those pieces of information that we attend to. Conversely, inattentiveness makes it all but impossible to memorize anything. More than just an item of purely academic interest, the link between attention and memory is especially relevant to how people master new language forms, both in their mother tongues and in foreign languages. However, despite the intuitively clear interdependence of attention and language knowledge, linguistic interest in studying the two in tandem is a relatively recent development. Perhaps this should not be too surprising, given that, beyond linguistics, research on the psychological processes involved in memory has, in general, had a rather up-and-down history. The beginnings of formal research on memory date back to some remarkable studies toward the end of the nineteenth century, when Hermann Ebbinghaus (1885) experimented on himself to determine how soon newly learned information is forgotten , or what he called the forgetting curve. He was the first to demonstrate that the forgetting curve is extended through repetition or active recall of new knowledge. Subsequent studies by others (e.g. Müller and Pilzecker, 1900; Semon, 1921; Bartlett, 1932) challenged or built on Ebbinghaus' findings, yielding important insights such as the discovery that memory is largely recon-structive and often unreliable. Then, there came a de facto hiatus in memory studies, a logical consequence of the behaviorist dismissal of memory as an incoherent notion (Delaney and Austin, 1998), eclipsed by the appeal of the stimulus-response-reinforcement mechanism. The pendulum swung again and research on memory resumed in earnest around the middle of the twentieth century, when Donald Hebb (1949) formulated his famous postulate of associative learning, under which neurons become joined into potentially permanent networks as a result of being activated at the same time. Psychology studies on attention and memory proliferated and influential models (e.g. Broadbent, 1958, discussed below) were proposed, but rather surprisingly, the role of attention in learning was initially not addressed in linguistic studies.
... 2021; Müller & Pilzecker, 1900). The transformation process from one phase to the other takes about 4 h post-training (Izquierdo et al., 2016), and if consolidation does not take place, the information is lost. ...
Memory and learning allow animals to appropriate certain properties of nature with which they can navigate in it successfully. Memory is acquired slowly and consists of two major phases, a fragile early phase (short‐term memory, <4 h) and a more robust and long‐lasting late one (long‐term memory, >4 h). Erythropoietin (EPO) prolongs memory from 24 to 72 h when animals are trained for 5 min in a place recognition task but not when training lasted 3 min (short‐term memory). It is not known whether it promotes the formation of remote memory (≥21 days). We address whether the systemic administration of EPO can convert a short‐term memory into a long‐term remote memory, and the neural plasticity mechanisms involved. We evaluated the effect of training duration (3 or 5 min) on the expression of endogenous EPO and its receptor to shed light on the role of EPO in coordinating mechanisms of neural plasticity using a single‐trial spatial learning test. We administered EPO 10 min post‐training and evaluated memory after 24 h, 96 h, 15 days, or 21 days. We also determined the effect of EPO administered 10 min after training on the expression of arc and bdnf during retrieval at 24 h and 21 days. Data show that learning induces EPO/EPOr expression increase linked to memory extent, exogenous EPO prolongs memory up to 21 days; and prefrontal cortex bdnf expression at 24 h and in the hippocampus at 21 days, whereas arc expression increases at 21 days in the hippocampus and prefrontal cortex.
... Memories are acquired and consolidated into long-term representations through a protein synthesis-dependent process (Müller and Pilzecker 1900;McGaugh 2000). However, consolidated memories are not static and inflexible. ...
Memories are stored into long-term representations through a process that depends on protein synthesis. However, a consolidated memory is not static and inflexible and can be reactivated under certain circumstances, the retrieval is able to reactivate memories and destabilize them engaging a process of restabilization known as reconsolidation. Although the molecular mechanisms that mediate fear memory reconsolidation are not entirely known, so here we investigated the molecular mechanisms in the hippocampus involved in contextual fear conditioning memory (CFC) reconsolidation in male Wistar rats. We demonstrated that the blockade of Src family kinases (SFKs), GluN2B-containing NMDA receptors and TrkB receptors (TrkBR) in the CA1 region of the hippocampus immediately after the reactivation session impaired contextual fear memory reconsolidation. These impairments were blocked by the neurotrophin BDNF and the NMDAR agonist, D-Serine. Considering that the study of the link between synaptic proteins is crucial for understanding memory processes, targeting the reconsolidation process may provide new ways of disrupting maladaptive memories, such as those seen in post-traumatic stress disorder. Here we provide new insights into the cellular mechanisms involved in contextual fear memory reconsolidation, demonstrating that SFKs, GluN2B-containing NMDAR, and TrkBR are necessary for the reconsolidation process. Our findings suggest a link between BDNF and SFKs and GluN2B-containing NMDAR as well as a link between NMDAR and SFKs and TrkBR in fear memory reconsolidation. These preliminary pharmacological findings provide new evidence of the mechanisms involved in the reconsolidation of fear memory and have the potential to contribute to the development of treatments for psychiatric disorders involving maladaptive memories.
... Consolidation of LTM requires gene expression and de novo protein synthesis (McGaugh, 2000). It has been assumed that STM formation is a necessary condition for LTM to be formed (Lechner et al., 1999;Müller & Pilzecker, 1900). ...
Actions from glial cells could affect the readiness and efficacy of learning and memory. Using a mouse cerebellar-dependent horizontal optokinetic response motor learning paradigm, short-term memory (STM) formation during the online training period and long-term memory (LTM) formation during the offline rest period were studied. A large variability of online and offline learning efficacies was found. The early bloomers with booming STM often had a suppressed LTM formation and late bloomers with no apparent acute training effect often exhibited boosted offline learning performance. Anion channels containing LRRC8A are known to release glutamate. Conditional knockout of LRRC8A specifically in astrocytes including cerebellar Bergmann glia resulted in a complete loss of STM formation while the LTM formation during the rest period remained. Optogenetic manipulation of glial activity by channelrhodopsin-2 or archaerhodopsin-T (ArchT) during the online training resulted in enhancement or suppression of STM formation, respectively. STM and LTM are likely to be triggered simultaneously during online training, but LTM is expressed later during the offline period. STM appears to be volatile and the achievement during the online training is not handed over to LTM. In addition, we found that glial ArchT photoactivation during the rest period resulted in the augmentation of LTM formation. These data suggest that STM formation and LTM formation are parallel separate processes. Strategies to weigh more on the STM or the LTM could depend on the actions of the glial cells.
... A key finding arguing against a merely passive role of sleep was reported by Ellenbogen et al. (2006a). The study directly relates to classic consolidation theory as pioneered by Müller and Pilzecker (1900); see also Wixted, 2004), who used retroactive interference to probe the stability of memories, arguing that consolidated memories should be less susceptible. Ellenbogen et al. (2006a) followed this rationale. ...
Numerous studies suggest that sleep benefits memory. A major theoretical question in this area is however if sleep does so by passively shielding memories from interference that arises during wakefulness or by actively stabilizing and strengthening memories. A key finding by Ellenbogen et al. Current Biology, 16, 1290-1294 (2006a) indicates that sleep can protect memories from retroactive interference, which suggests that sleep plays more than a passive role for memory consolidation. Sample size in this study was however small and subsequent reports in the literature provided mixed results. We therefore conducted an online study via Zoom to replicate Ellenbogen et al. Current Biology, 16, 1290-1294 (2006a). Subjects were asked to study paired associates. After a 12-h delay that included either nocturnal sleep or daytime wakefulness, half of all subjects were asked to study an additional list to elicit retroactive interference. All participants were then asked to complete a memory test for the studied list(s). The results were fully consistent with those reported by Ellenbogen et al. Current Biology, 16, 1290-1294 (2006a). We discuss this successful replication against the background of the mixed literature, with a focus on the possibly critical role of study-design features, like the use of high learning criteria that resulted in performance being at ceiling, or a confound between interference and the length of the retention interval. A collaborative replication effort may be needed to reach a straightfoward answer to the question if sleep protects memories from interference (and under what conditions).
... A long-standing hypothesis is that many forms of forgetting are due to multiple memory traces encoded closely in time, competing to be consolidated in the brain [1,[20][21][22]. ...
Long-term memories are stored as stable configurations of neuronal ensembles, termed engrams. While investigation of engram cell properties and functionality in memory recall has been extensive, less is known about how engram cells are affected by forgetting. We describe a form of interference-based forgetting using an object memory behavioral paradigm. By using activity-dependent cell labelling, we show that although retroactive interference results in decreased engram cell reactivation during recall trials, optogenetic stimulation of the labelled engram cells is sufficient to induce memory retrieval. Forgotten engrams may also be reinstated via the presentation of similar or related environmental information. Furthermore, we demonstrate that engram activity is necessary for interference to occur. Taken together, these findings indicate that retroactive interference modulates engram expression in a manner that is both reversible and updatable. Retroactive inference may constitute a form of adaptive forgetting, where in everyday life new perceptual and environmental inputs modulate the natural forgetting process.
... Rather, research over the last 120 years has shown that such failure of memory often occurs when, prior to the retrieval attempt, additional nontarget information related to the target information has been studied (for reviews, see Kliegl & Bäuml, 2021;Wixted, 2004). One prominent form of this so-called interference-induced forgetting is retroactive interference (RI; Müller & Pilzecker, 1900), which is typically observed when between study and test of the target information, related nontarget information is encountered. ...
Taking a pretest (e.g., blanket – ?) before some target material (blanket – sheet) is studied can promote recall of that material on a subsequent final test compared to material which was initially only studied. Here, we examine whether such pretesting can shield the tested material from interference-induced forgetting, which often occurs when before final testing, related material is encountered. We applied a typical pretesting task but asked subjects, between acquisition and final testing of the target list (list 1), to study two additional lists of items with either completely new and unique pairs (e.g., atom – cell) or overlapping – and thus potentially interfering – pairs (e.g., blanket – sleep). Target-list recall on the final test showed a typical pretesting effect for unique pairs, but the size of the effect even increased for overlapping pairs, as recall of study-only pairs was impaired, whereas recall of pretest pairs was left largely unaffected. This held regardless of whether a low (Experiment 1) or high (Experiment 2) degree of learning was induced for the interfering material, suggesting that pretesting can indeed protect the tested material from interference. These findings indicate that pretesting could play a significant role in educational settings where information often needs to be retained in the presence of competing information.
... One of the reasons we fail to remember is, after we experience the tobe-remembered event, something interferes with the memory. This interference of new information on the encoding or retrieval of memories has a long history of differentiating memory systems through finding sensitive periods where a memory is particularly susceptible to be interfered with (e.g., Atkinson & Shiffrin, 1968;Averbach & Coriell, 1961;Lechner et al., 1999;Müller & Pilzecker, 1900;Thorndike, 1913;Waugh & Norman, 1965). ...
Verbalizing visual memories can interfere with later accurate recall. Whereas changes in the magnitude of this verbal overshadowing effect (VOE) as a function of delay have been reported, no study has systematically investigated multiple shorter nonimmediate delays. Does VOE happen when verbalization occurs 5-min postencoding? 10 min? 15 min? We show in a preregistered study involving 4,501 American adults randomly assigned to different timing paradigms, that the effect size of VOE at 5 or 10 min is nearly zero, with a stable and significant inhibitory effect from 15 to 20 min. We further investigate this nonlinearity in a second study of 3,174 individuals showing a distinct nonlinear “effect amplification” sometime between 12 and 14 min. This apparent critical period after stimulus onset where susceptibility to verbal interference dramatically increases may help explain potential difficulties replicating VOE. More importantly, it suggests the possibility that the 12–14 min period may represent a critical window for other interference paradigms as well.
... The first hypothesis proposes that the memories that survive early threats from competing new information become hardened or immune to the effects of interference. This hypothesis is typically called memory consolidation theory [66][67][68]. Consolidation theory assumes that new encodings are fragile like a fresh painting. However, with the passage of time, the encoding is hardened into a permanent representation like the drying of wet paint. ...
The retention of human memory is a process that can be understood from a hazard-function perspective. Hazard is the conditional probability of a state change at time t given that the state change did not yet occur. After reviewing the underlying mathematical results of hazard functions in general, there is an analysis of the hazard properties associated with nine theories of memory that emerged from psychological science. Five theories predict strictly monotonically decreasing hazard whereas the other four theories predict a peaked-shaped hazard function that rises initially to a peak and then decreases for longer time periods. Thus, the behavior of hazard shortly after the initial encoding is the critical difference among the theories. Several theorems provide a basis to explore hazard for the initial time period after encoding in terms of a more practical surrogate function that is linked to the behavior of the hazard function. Evidence for a peak-shaped hazard function is provided and a case is made for one particular psychological theory of memory that posits that memory encoding produces two redundant representations that have different hazard properties. One memory representation has increasing hazard while the other representation has decreasing hazard.
... Regarding vocals, evidence exists that memory interference can occur between information that is similar in its content, for instance when verbal encoding material is processed simultaneously or in short succession with verbal distractor material, resulting in a decreased memory performance (e.g. Dewar et al., 2007;Jones & Macken, 1993;Müller & Pilzecker, 1900). Thus, it is conceivable that vocals included in our musical excerpts eventually interfered with consolidation leading to a decreased memory performance after 1 day. ...
Wakeful resting and listening to music are powerful means to modulate memory. How these activities affect memory when directly compared has not been tested so far. In two experiments, participants encoded and immediately recalled two word lists followed by either 6 min wakefully resting or 6 min listening to music. The results of Experiment 1 show that both post-encoding conditions have a similar effect on memory after 1 day. In Experiment 2, we explored the possibility that less concrete words, i.e. lower in imageability than in Experiment 1, are differently affected by the two post-encoding conditions. The results of Experiment 2 show that, when words are less concrete, more words are retained after 1 day when encoding is followed by wakeful resting rather than listening to music. These findings indicate that the effects of wakeful resting and listening to music on memory consolidation are moderated by the concreteness of the encoded material.
... En neurosciences cognitives, la consolidation de la mémoire désigne le processus par lequel la trace mnésique nouvellement acquise est transférée d'un système de mémoire à court terme vers la mémoire à long terme où elle se stabilise 1 [3]. Il y a déjà plus d'un siècle, Müller et Pilzecker, à qui l'on doit la première théorie de la consolidation, ont démontré que la présentation de « stimuli distractifs » altère les capacités de rappel d'informations récemment acquises [4]. S'appuyant sur ces travaux, de récentes études apportent davantage d'éléments de précision relatifs à la nature de ces stimuli [5,6]. ...
Dès les années 1960, les chercheurs en neurosciences ont mis en évidence qu’un souvenir récemment acquis est fragile et doit être stabilisé pour devenir permanent (consolidation). Dans les années 2000, ils ont constaté que les souvenirs anciens redeviennent instables et susceptibles d’être modifiés lorsqu’ils sont réactivés (reconsolidation). Ils ont montré que l’hyperactivité neurovégétative facilite la consolidation des souvenirs et explique, du moins partiellement, la chronicisation du syndrome psychotraumatique. Ils ont également prouvé qu’il est possible d’atténuer les émotions d’un souvenir ancien au moment de sa reconsolidation.
... Memory consolidation refers to the process of transforming a vulnerable memory trace into an enduring state by increasing its resistance to interference (Müller & Pilzecker, 1900). Since the 1920s, sleep has been implicated in this process, as Jenkins and Dallenbach reported that experimental subjects remembered more non-sensical syllables after a period of sleep compared to a period of wake, leading the authors to suggest that sleep passively facilitates episodic memory via reduced interference (Jenkins & Dallenbach, 1924). ...
Prior studies suggest a role for sleep in memory consolidation, with specific contributions from slow oscillations and sleep spindles (Rasch & Born, 2013). However, recent studies failed to replicate sleep’s superiority over wake in strengthening memory against interference (Cordi & Rasch, 2021). The goal of the current study is to investigate whether sleep protects newly formed memory from unspecific interference induced by daytime experiences over 24 hours, as well as to elucidate the sleep features that are involved. 56 healthy adults were randomly assigned to either the Sleep First or Wake First group. The Sleep First group encoded word pairs at night before sleep, while the Wake First group encoded word pairs in the morning before a day of wakefulness. Memory was tested 30 minutes, 12 hours, and 24 hours after encoding for both groups. The Sleep First group performed significantly better 12 hours after encoding, replicating prior findings that memory is better after a period of sleep compared to wake. However, after 24 hours, the two groups performed similarly. The Wake First group showed a positive correlation between overnight memory improvement and the theta and delta band power during slow wave sleep, an effect not found in the Sleep First group. These correlations suggest the possibility that after a day of waking interference, the brain recruits extra sleep resources to rescue memories from further forgetting. Our results are not consistent with prior studies showing a significant role for sleep in stabilizing memory from future interference, but they may suggest that sleep rescues memories after interference has occurred.
... One of the major causes of forgetting is interference phenomena [10][11][12], whereby conflicting information impairs consolidating and/or recollecting a previously acquired memory that can explain severe memory impairments in amnestic and Alzheimer's disease with increased susceptibility to interference effects [13][14][15]. Specifically, retroactive interference involves the disruption of previously encoded information by newly learned information and, thus, may impair the consolidation of long-term memory [16][17][18]. Such an "interference stimulus" may be introduced into the social memory paradigm in rodents in order to gain insight into the cellular mechanisms underlying the generation of long-term social memory [19,20]. ...
Previous studies have shown that atypical dopamine-transporter-inhibitors such as modafinil and its analogues modify behavioral and cognitive functions in rodents. Here, we tested potential promnestic effects of the novel, more dopamine-transporter selective modafinil analogue CE-158 in the social discrimination memory task in male mice. Systemic administration of CE-158 1 h before the social learning event prevented the impairment of social-recognition memory following retroactive interference 3 h after the learning session of a juvenile conspecific. This effect was dose-dependent, as mice treated with 10 mg/kg, but not with 1 mg/kg CE-158, were able to discriminate between the novel and familiar conspecific despite the presentation of an interference stimulus, both 3 h and 6 h post learning. However, when 10 mg/kg of the drug was administered after learning, CE-158 failed to prevent social memory from interference. Paralleling these behavioral effects, the systemic administration of 10 mg/kg CE-158 caused a rapid and sustained elevation of extracellular dopamine in the nucleus accumbens, a brain area where dopaminergic signaling plays a key role in learning and memory function, of freely moving mice, while 1 mg/kg was not sufficient for altering dopamine levels. Taken together, our findings suggest promnestic effects of the novel dopamine-transporter-inhibitor CE-158 in a social recognition memory test that may be in part mediated via increased dopamine-neurotransmission in the nucleus accumbens. Thus, selective-dopamine-transporter-inhibitors such as CE-158 may represent interesting drug candidates for the treatment of memory complaints observed in humans with cognitive impairments and dementia.
... Cognitive interventions involving a taxing visuospatial task (henceforth "visuospatial" tasks), such as the Tetris intervention and complex pattern tapping, have demonstrated efficacy for reducing the trajectory of intrusive memory frequency following exposure to an analog traumatic event, when administered in the memory consolidation phase (5)(6)(7)(8). Memory consolidation, first referred to over a century ago by Muller and Pilzecker (9), is the stabilization of memories involving transition of memories from short-to long-term storage via protein synthesis (10). The consolidation process is said to occur within 6-h of exposure to an event (11). ...
Cognitive interventions involving visuospatial tasks, such as the game “Tetris” have demonstrated efficacy in reducing the frequency of intrusive memories. However, it remains unclear whether these tasks also reduce the perceived intensity and distress of these memories. We investigated whether either of two visuospatial tasks: a Tetris intervention or Digital Corsi task, following the viewing of an analog trauma (film) resulted in decreased intensity and distress for intrusive memories over the following week, when compared to a control condition. Participants (n = 110) were randomly assigned to task conditions after viewing the film. Linear mixed models indicated no between-group differences for reductions in intensity or distress over the course of the week. These findings highlight an important boundary to the benefits of such visuospatial tasks, in that while they may be associated with reductions in intrusion memory frequency, individuals may nonetheless continue to experience distress when intrusions do occur.
Everyday experiences often overlap, challenging our ability to maintain distinct episodic memories. One way to resolve such interference is by exaggerating subtle differences between remembered events, a phenomenon known as memory repulsion. Here, we tested whether repulsion is influenced by emotional arousal, when resolving memory interference is perhaps most needed. We adapted an existing paradigm in which participants repeatedly studied object–face associations. Participants studied two different-colored versions of each object: a to-be-tested “target” and its not-to-be-tested “competitor” pair mate. The level of interference between target and competitor pair mates was manipulated by making the object colors either highly similar or less similar, depending on the participant group. To manipulate arousal, the competitor object–face associations were preceded by either a neutral tone or an aversive and arousing burst of white noise. Memory distortion for the color of the target objects was tested after each study round to examine whether memory distortions emerge after learning. We found that participants with greater sound-induced pupil dilations, an index of physiological arousal, showed greater memory attraction of target colors towards highly similar competitor colors. Greater memory attraction was also correlated with greater memory interference in the last round of learning. Additionally, individuals who self-reported higher trait anxiety showed greater memory attraction when one of the overlapping memories was associated with something aversive. Our findings suggest that memories of similar neutral and arousing events may blur together after repeated exposures, especially in individuals who show higher arousal responses and symptoms of anxiety.
The medial prefrontal cortex (mPFC) plays a critical role in recalling recent and remote fearful memories. Modern neuroscience techniques, such as projection-specific circuit manipulation and activity-dependent labeling, have illuminated how mPFC memory ensembles are reorganized over time. This chapter discusses the implications of new findings for traditional theories of memory, such as the systems consolidation theory and theories of memory engrams. It also examines the specific contributions of mPFC subregions, like the prelimbic and infralimbic cortices, in fear memory, highlighting how their distinct connections influence memory recall. Further, it elaborates on the cellular and molecular changes within the mPFC that support memory persistence and how these are influenced by interactions with the hippocampus. Ultimately, this chapter provides insights into how lasting memories are dynamically encoded in prefrontal circuits, arguing for a key role of memory ensembles that extend beyond strict definitions of the engram.
The claustrum is a brain structure that remains shrouded in mystery due to the limited understanding of its cellular structure, neural pathways, functionality and physiological aspects. Significant research has unveiled connections spanning from the claustrum to the entire cortex as well as subcortical areas. This widespread connectivity has led to speculations of its role in integrating information from different brain regions, possibly contributing to processes such as attention, consciousness, learning and memory. Our working hypothesis posits that claustrum neural activity contributes to the formation, stabilization and updating of long-term memories in mice. We found evidence in CF-1 mice of a decline in behavioral performance in an inhibitory avoidance task due to intra-claustral administration of 2% lidocaine immediately after a training session or memory recall. Nevertheless, this does not seem to be the case for the acquisition or retrieval of this type of memory, although its neural activity is significantly increased after training, evaluated through c-Fos expression. Moreover, inhibition of the claustrum's synaptic activity appears to impair stabilization but not the acquisition or retrieval of an unconditioned memory formed in a nose-poke habituation task.
Cognitive science is a cross-disciplinary enterprise devoted to understanding the nature of the mind. In recent years, investigators in philosophy, psychology, the neurosciences, artificial intelligence, and a host of other disciplines have come to appreciate how much they can learn from one another about the various dimensions of cognition. The result has been the emergence of one of the most exciting and fruitful areas of inter-disciplinary research in the history of science. This volume of original essays surveys foundational, theoretical, and philosophical issues across the discipline, and introduces the foundations of cognitive science, the principal areas of research, and the major research programs. With a focus on broad philosophical themes rather than detailed technical issues, the volume will be valuable not only to cognitive scientists and philosophers of cognitive science, but also to those in other disciplines looking for an authoritative and up-to-date introduction to the field.
Memories are experience-dependent internal representations of the world that can last from short periods of time to a whole life. The formation of long-term memories relies on several biochemical changes, which inducing modifications in the synaptic efficiency change the way the neurons communicate each other. Interestingly, the formation of a lasting memory does not entirely depend on learning itself; different events occurring before or after a particular experience can affect its processing, impairing, improving or even inducing lasting memories. The overlapping of neuronal networks involved in the processing of different types of learning might explain why different experiences interact at neuronal level. However, how and where this does really happen is an issue of study.
In 1997, the Synaptic Tagging and Capture hypothesis provided a strong framework to explain how synaptic specificity can be achieved when inducing long-lasting changes in electrophysiological models of functional plasticity. Ten years later, an analogous argument was used in learning and memory models to postulate the Behavioral Tagging hypothesis. This framework provided solid explanation of how weak events, only capable of inducing transient forms of memories, can result in lasting memories when occurring in the context of other behaviorally relevant experiences. The hypothesis postulates that the formation of lasting memories rely on at least two parallel processes: (1) the setting of a learning tag that determines which memory could be stored and where and (2) the synthesis of plasticity-related proteins, which once captured at tagged sites will allow the consolidation of a memory for long periods of time. Therefore, a weak learning, only able to induce transient forms of memories but also capable of setting a learning tag, could be benefited from the proteins synthesized by a different strong event, processed in the same areas, by using them to consolidate its own lasting memory.
In this chapter, we detail the postulates and predictions of the Behavioral Tagging hypothesis. We review the bibliography covering the 15 years from the postulation of the hypothesis to deepen into the mechanisms associated with tag setting and the synthesis of proteins. And we discuss its implications on memory formation and its persistence.
Four experiments studied the effects of context change and retention interval on retroactive interference in human causal learning. Experiment 1 found evidence of retroactive interference. Experiment 2 found that either a 48-hr retention interval or a change in the context after the interference treatment decreased retroactive interference. An interaction between context change and retention interval effects was also found, eclipsing the context change effect after the 48-hr retention interval. Experiments 3 and 4 found additivity between context change and retention interval effects when participants were reminded of the difference between physical contexts before the test, independently of whether the context change involved a return to the original acquisition context. These results add to the evidence suggesting that spontaneous forgetting is caused by a change in either the physical or the temporal contexts where information is acquired.
The eyewitness literature often claims that emotional stress leads to an impairment in memory and, hence, that details of unpleasant emotional events are remembered less accurately than details of neutral or everyday events. A common assumption behind this view is that a decrease in available processing capacity occurs at states of high emotional arousal, which, therefore, leads to less efficient memory processing. The research reviewed here shows that this belief is overly simplistic. Current studies demonstrate striking interactions between type of event, type of detail information, time of test, and type of retrieval information. This article also reviews the literature on memory for stressful events with respect to two major theories: the Yerkes-Dodson law and Easter-brook's cue-utilization hypothesis. To account for the findings from real-life studies and laboratory studies, this article discusses the possibility that emotional events receive some preferential processing mediated by factors related to early perceptual processing and late conceptual processing.
Long-term memories are stored as configurations of neuronal ensembles, termed engrams. Although investigation of engram cell properties and functionality in memory recall has been extensive, less is known about how engram cells are affected by forgetting. We describe a form of interference-based forgetting using an object memory behavioral paradigm. By using activity-dependent cell labeling, we show that although retroactive interference results in decreased engram cell reactivation during recall trials, optogenetic stimulation of the labeled engram cells is sufficient to induce memory retrieval. Forgotten engrams may be reinstated via the presentation of similar or related environmental information. Furthermore, we demonstrate that engram activity is necessary for interference to occur. Taken together, these findings indicate that retroactive interference modules engram expression in a manner that is both reversible and updatable. Inference may constitute a form of adaptive forgetting where, in everyday life, new perceptual and environmental inputs modulate the natural forgetting process.
The Cambridge Handbook of Computational Cognitive Sciences is a comprehensive reference for this rapidly developing and highly interdisciplinary field. Written with both newcomers and experts in mind, it provides an accessible introduction of paradigms, methodologies, approaches, and models, with ample detail and illustrated by examples. It should appeal to researchers and students working within the computational cognitive sciences, as well as those working in adjacent fields including philosophy, psychology, linguistics, anthropology, education, neuroscience, artificial intelligence, computer science, and more.
Even after successful extinction, conditioned fear can return. Strengthening the consolidation of the fear-inhibitory safety memory formed during extinction is one way to counteract return of fear. In this preregistered direct replication study in male participants, we confirm that spontaneous post-extinction reactivations of a neural activation pattern evoked in the ventromedial prefrontal cortex (vmPFC) during extinction predict extinction memory retrieval 24 h later. We do not confirm that L-DOPA administration after extinction enhances retrieval and that this is mediated by enhancement of the number of vmPFC reactivations. However, additional non-preregistered analyses reveal a beneficial effect of L-DOPA on extinction retrieval when controlling for the trait-like stable baseline levels of salivary alpha-amylase enzymatic activity (trait sAA) levels that participants show on the three experimental days. Further, trait sAA negatively predicts retrieval, and this effect is rescued by L-DOPA treatment. Our results suggest that individuals with high basal levels of sympathetic nervous system (SNS) activity may have poor extinction and that L-DOPA may be selectively beneficial for these individuals, which holds potential for clinical applications.
It is generally thought that children learn more efficiently than adults. One way to accomplish this is to have learning rapidly stabilized such that it is not interfered with by subsequent learning. Although γ-aminobutyric acid (GABA) plays an important role in stabilization, it has been reported that GABAergic inhibitory processing is not fully matured yet in children compared with adults. Does this finding indicate that more efficient learning in children is not due to more rapid stabilization? Here, we measured the concentration of GABA in early visual cortical areas in a time-resolved fashion before, during, and after visual perceptual learning (VPL) within subjects using functional MRS (fMRS) and then compared the concentrations between children (8 to 11 years old) and adults (18 to 35 years old). We found that children exhibited a rapid boost of GABA during visual training that persisted after training ended, whereas the concentration of GABA in adults remained unchanged. Moreover, behavioral experiments showed that children exhibited rapid development of resilience to retrograde interference, which indicates that children stabilize VPL much faster than adults. These results together suggest that inhibitory processing in children’s brains is more dynamic and adapts more quickly to stabilize learning than in adults, making learning more efficient in children.
The field of autobiographical memory has made dramatic advances since the first collection of papers in the area was published in 1986. Now, over 25 years on, this book reviews and integrates the many theories, perspectives, and approaches that have evolved over the last decades. A truly eminent collection of editors and contributors appraise the basic neural systems of autobiographical memory; its underlying cognitive structures and retrieval processes; how it develops in infancy and childhood, and then breaks down in aging; its social and cultural aspects; and its relation to personality and the self. Autobiographical memory has demonstrated a strong ability to establish clear empirical generalizations, and has shown its practical relevance by deepening our understanding of several clinical disorders - as well as the induction of false memories in the legal system. It has also become an important topic for brain studies, and helped to enlarge our general understanding of the brain.
Although memory has long been recognized as a generative process, neural research of memory in recent decades has been predominantly influenced by Tulving’s “mental time traveling” perspective and focused on the reactivation and consolidation of encoded memory representations. With the development of multiple powerful analytical approaches to characterize the contents and formats of neural representations, recent studies are able to provide detailed examinations of the representations at various processing stages and have provided exciting new insights into the transformative nature of episodic memory. These studies have revealed the rapid, substantial, and continuous transformation of memory representation during the encoding, maintenance, consolidation, and retrieval of both single and multiple events, as well as event sequences. These transformations are characterized by the abstraction, integration, differentiation, and reorganization of memory representations, enabling the long-term retention and generalization of memory. These studies mark a significant shift in perspective from remembering to reconstruction, which might better reveal the nature of memory and its roles in supporting more effective learning, adaptive decision-making, and creative problem solving.
Memory consolidation is a continuous transformative process between encoding and retrieval of mental representations. Recent research has shown that neural activity immediately after encoding is particularly associated with later successful retrieval. It is currently unclear whether post-encoding neural activity makes a distinct and causal contribution to memory consolidation. Here, we investigated the role of the post-encoding period for consolidation of spatial memory in neurologically normal human subjects. We used the GABAA-ergic anesthetic propofol to transiently manipulate neural activity during the initial stage of spatial memory consolidation without affecting encoding or retrieval. A total of 52 participants undergoing minor surgery learned to navigate to a target in a five-armed maze derived from animal experiments. Participants completed learning either immediately prior to injection of propofol (early group) or more than 60 minutes before injection (late group). Four hours after anesthesia, participants were tested for memory-guided navigation. Our results show a selective impairment of navigation in the early group and near-normal performance in the late group. Analysis of navigational error patterns further suggested that propofol impaired distinct aspects of spatial representations, in particular sequences of path segments and spatial relationships between landmarks. We conclude that neural activity during the post-encoding period makes a causal and specific contribution to consolidation of representations underlying self-centered and world-centered memory-guided navigation. Distinct aspects of these representations are susceptible to GABAA-ergic modulation within a post-encoding time-window of less than 60 minutes, presumably reflecting associative processes that contribute to the formation of integrated spatial representations that guide future behavior.
We model a decision maker who observes available alternatives according to a list and stochastically forgets some alternatives. Each time the decision maker observes an item in the list, she recalls previous alternatives with some probability, conditional on those alternatives being recalled until this point. The decision maker maximizes a preference relation over the set of alternatives she can recall. We show that if every available alternative is chosen with strictly positive probability, the preference order and the list order must coincide in any limited memory representation. Under the full support assumption, the preference ordering, the list ordering and the memory parameters are uniquely identified up to the ranking of the two least preferred alternatives. We provide conditions on observable choice probabilities that characterize the model under the full support assumption. We then apply our model to study the pricing problem of a monopolist who faces consumers with limited memory. We show that when the probability of forgetting is high, the monopolist is better off charging a lower price than the optimal price in the perfect memory case.
Memory consolidation—the transformation of labile memory traces into stable long-term representations—is facilitated by post-learning sleep. Computational and biophysical models suggest that sleep spindles may play a key mechanistic role for consolidation, igniting structural changes at cortical sites involved in prior learning. Here, we tested the resulting prediction that spindles are most pronounced over learning-related cortical areas and that the extent of this learning-spindle overlap predicts behavioral measures of memory consolidation. Using high-density scalp electroencephalography (EEG) and polysomnography (PSG) in healthy volunteers, we first identified cortical areas engaged during a temporospatial associative memory task (power decreases in the alpha/beta frequency range, 6–20 Hz). Critically, we found that participant-specific topographies (i.e., spatial distributions) of post-learning sleep spindle amplitude correlated with participant-specific learning topographies. Importantly, the extent to which spindles tracked learning patterns further predicted memory consolidation across participants. Our results provide empirical evidence for a role of post-learning sleep spindles in tracking learning networks, thereby facilitating memory consolidation.
Memory for time is influenced by reconstructive processes, but the underlying mechanisms remain unclear. The present study investigated whether the effect of schematic prior knowledge on temporal memory for movie scenes, produced by the incomplete presentation (cut) of the movie at encoding, is modulated by cut position, retention interval, and task repetition. In a timeline positioning task, participants were asked to indicate when short video clips extracted from a previously encoded movie occurred on a horizontal timeline that represented the video duration. In line with previous findings, removing the final part of the movie resulted in a systematic underestimation of clips' position as a function of their proximity to the missing part. Further experiments demonstrate that the direction of this automatic effect depends on which part of the movie is deleted from the encoding session, consistent with the inferential structure of the schema, and does not depend on consolidation nor reconsolidation processes, at least within the present experimental conditions. We propose that the observed bias depends on the automatic influence of reconstructive processes on judgments about the time of occurrence, based on prior schematic knowledge.
L’objectif de ce travail de thèse est d’étudier les mécanismes de la mémoire à long terme des durées et son actualisation chez l’Homme et l’animal. Dans ce but, 6 expériences ont été réalisées, réparties dans 3 axes de recherche. Le premier axe de recherche concernait l’étude des mécanismes du jugement temporel en mémoire à long terme chez l’homme adulte et ses variations selon les gammes de durées stockées en mémoire : des durées inférieures à 1s (600ms), entre 1 et 3s (2.5s), et supérieures à 3s (4s comme dans l’étude de Cocenas et al., 2014, et 8s). Les résultats montrent que le jugement du temps en mémoire à long terme suit les propriétés de la théorie du temps scalaire. Ainsi, le souvenir de la durée reste en moyenne précis pour toutes les gammes de durées. La variabilité du jugement temporel augmente lorsque les durées à juger deviennent de plus en plus longues. De plus, les résultats semblent confirmer qu’il existe bien un processus de consolidation d’une durée en mémoire. Ce processus de consolidation des durées est également particulièrement sensible aux effets d’interférence. Le second axe de recherche avait pour objectif d’analyser l’actualisation d’une durée en mémoire de référence chez l’être humain et sa sensibilité à l’interférence, à la fois chez l’enfant et l’adulte. Les résultats indiquent que l’apprentissage d’une première durée impacte peu l’apprentissage d’une seconde durée. L’effet d’interférence fonctionne lorsque les deux durées sont proches (ex : 3s et 4s) mais s’estompe très rapidement lorsque l’intervalle entre les deux durées augmentent. Enfin, l’objectif du troisième axe était de mettre en place un protocole expérimental chez le rat, afin de mesurer l’actualisation d’une durée en mémoire à long terme. Les résultats montrent que les rats peuvent apprendre une nouvelle durée très rapidement, et ce lors d’une unique séance. L’actualisation de la durée, chez les rats, a été observée sur différentes durées cibles. L’apprentissage d’une nouvelle durée se traduit également par un effet d’asymétrie temporelle : allongement temporel.
Significance
Recall of encoded information gets impaired as time passes. We show that selective retrieval can interrupt such time-dependent forgetting. Selective retrieval of some studied information can revive the nonretrieved information and bring recall levels back to the levels shortly after study. Strikingly, we found that time-dependent forgetting after selective retrieval mimics time-dependent forgetting after study, which implies that the revival of the forgotten memories is lasting and caused by a reset of the recall process. In the real world, retrieval of encoded episodes is often selective and is often time-lagged, like in educational settings or in eyewitness testimony situations. Our findings suggest that selective retrieval can improve people’s memory in such situations.
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