-
Cell Reports Aug 2023Long-term memories are stored as configurations of neuronal ensembles, termed engrams. Although investigation of engram cell properties and functionality in memory...
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.
Topics: Memory; Memory, Long-Term; Mental Recall; Optogenetics
PubMed: 37590145
DOI: 10.1016/j.celrep.2023.112999 -
Cognition Dec 2022When people make risky decisions based on past experience, they must rely on memory. The nature of the memory representations that support these decisions is not yet...
When people make risky decisions based on past experience, they must rely on memory. The nature of the memory representations that support these decisions is not yet well understood. A key question concerns the extent to which people recall specific past episodes or whether they have learned a more abstract rule from their past experience. To address this question, we examined the precision of the memories used in risky decisions-from-experience. In three pre-registered experiments, we presented people with risky options, where the outcomes were drawn from continuous ranges (e.g., 100-190 or 500-590), and then assessed their memories for the outcomes experienced. In two preferential tasks, people were more risk seeking for high-value than low-value options, choosing as though they overweighted the outcomes from more extreme ranges. Moreover, in two preferential tasks and a parallel evaluation task, people were very poor at recalling the exact outcomes encountered, but rather confabulated outcomes that were consistent with the outcomes they had seen and were biased towards the more extreme ranges encountered. This common pattern suggests that the observed decision bias in the preferential task reflects a basic cognitive process to overweight extreme outcomes in memory. These results highlight the importance of the edges of the distribution in providing the encoding context for memory recall. They also suggest that episodic memory influences decision-making through gist memory and not through direct recall of specific instances.
Topics: Decision Making; Humans; Learning; Memory, Episodic; Mental Recall; Risk-Taking
PubMed: 35961162
DOI: 10.1016/j.cognition.2022.105245 -
Proceedings. Biological Sciences Jun 2022When we bring to mind something we have seen before, our eyes spontaneously unfold in a sequential pattern strikingly similar to that made during the original encounter,...
When we bring to mind something we have seen before, our eyes spontaneously unfold in a sequential pattern strikingly similar to that made during the original encounter, even in the absence of supporting visual input. Oculomotor movements of the eye may then serve the opposite purpose of acquiring new visual information; they may serve as self-generated cues, pointing to stored memories. Over 50 years ago Donald Hebb, the forefather of cognitive neuroscience, posited that such a sequential of eye movements supports our ability to mentally recreate visuospatial relations during episodic remembering. However, direct evidence for this influential claim is lacking. Here we isolate the sequential properties of spontaneous eye movements during encoding and retrieval in a pure recall memory task and capture their encoding-retrieval overlap. Critically, we show that the fidelity with which a series of consecutive eye movements from initial encoding is sequentially retained during subsequent retrieval predicts the quality of the recalled memory. Our findings provide direct evidence that such are replayed to assemble and reconstruct spatio-temporal relations as we remember and further suggest that distinct scanpath properties differentially contribute depending on the nature of the goal-relevant memory.
Topics: Cues; Eye Movements; Memory, Episodic; Mental Recall
PubMed: 35703049
DOI: 10.1098/rspb.2022.0964 -
Proceedings of the National Academy of... Oct 2022Episodic autobiographical memories are characterized by a spatial context and an affective component. But how do affective and spatial aspects interact? Does affect...
Episodic autobiographical memories are characterized by a spatial context and an affective component. But how do affective and spatial aspects interact? Does affect modulate the way we encode the spatial context of events? We investigated how one element of affect, namely aesthetic liking, modulates memory for location, in three online experiments ( = 124, 79, and 80). Participants visited a professionally curated virtual art exhibition. They then relocated previously viewed artworks on the museum map and reported how much they liked them. Across all experiments, liking an artwork was associated with increased ability to recall the wall on which it was hung. The effect was not explained by viewing time and appeared to modulate recognition speed. The liking-wall memory effect remained when participants attended to abstractness, rather than liking, and when testing occurred 24 h after the museum visit. Liking also modulated memory for the room where a work of art was hung, but this effect primarily involved reduced room memory for disliked artworks. Further, the liking-wall memory effect remained after controlling for effects of room memory. Recalling the wall requires recalling one's facing direction, so our findings suggest that positive aesthetic experiences enhance first-person spatial representations. More generally, a first-person component of positive affect transfers to wider spatial representation and facilitates the encoding of locations in a subject-centered reference frame. Affect and spatial representations are therefore important, and linked, elements of sentience and subjectivity. Memories of aesthetic experiences are also spatial memories of how we encountered a work of art. This linkage may have implications for museum design.
Topics: Emotions; Esthetics; Humans; Memory, Episodic; Mental Recall; Museums
PubMed: 36251990
DOI: 10.1073/pnas.2201540119 -
Psychonomic Bulletin & Review Oct 2022When memories share similar features, this can lead to interference, and ultimately forgetting. With experience, however, interference can be resolved. This raises the...
When memories share similar features, this can lead to interference, and ultimately forgetting. With experience, however, interference can be resolved. This raises the important question of how memories change, with experience, to minimize interference. Intuitively, interference might be minimized by increasing the precision and accuracy of memories. However, recent evidence suggests a potentially adaptive role for memory distortions. Namely, similarity can trigger exaggerations of subtle differences between memories (repulsion). Here, we tested whether repulsion specifically occurs on feature dimensions along which memories compete and whether repulsion is predictive of reduced memory interference. To test these ideas, we developed synthetic faces in a two-dimensional face space (affect and gender). This allowed us to precisely manipulate similarity between faces and the feature dimension along which faces differed. In three experiments, participants learned to associate faces with unique cue words. Associative memory tests confirmed that when faces were similar (face pairmates), this produced interference. Using a continuous face reconstruction task, we found two changes in face memory that preferentially occurred along the feature dimension that was "diagnostic" of the difference between face pairmates: (1) there was a bias to remember pairmates with exaggerated differences (repulsion) and (2) there was an increase in the precision of feature memory. Critically, repulsion and precision were each associated with reduced associative memory interference, but these were statistically dissociable contributions. Collectively, our findings reveal that similarity between memories triggers dissociable, experience-dependent changes that serve an adaptive role in reducing interference.
Topics: Humans; Learning; Memory; Memory, Long-Term; Mental Recall
PubMed: 35380409
DOI: 10.3758/s13423-022-02082-4 -
Current Biology : CB Jan 2012Learning new facts and skills in succession can be frustrating because no sooner has new knowledge been acquired than its retention is being jeopardized by learning... (Review)
Review
Learning new facts and skills in succession can be frustrating because no sooner has new knowledge been acquired than its retention is being jeopardized by learning another set of skills or facts. Interference between memories has recently provided important new insights into the neural and psychological systems responsible for memory processing. For example, interference not only occurs between the same types of memories, but can also occur between different types of memories, which has important implications for our understanding of memory organization. Converging evidence has begun to reveal that the brain produces interference independently from other aspects of memory processing, which suggests that interference may have an important but previously overlooked function. A memory's initial susceptibility to interference and subsequent resistance to interference after its acquisition has revealed that memories continue to be processed 'off-line' during consolidation. Recent work has demonstrated that off-line processing is not limited to just the stabilization of a memory, which was once the defining characteristic of consolidation; instead, off-line processing can have a rich diversity of effects, from enhancing performance to making hidden rules explicit. Off-line processing also occurs after memory retrieval when memories are destabilized and then subsequently restabalized during reconsolidation. Studies are beginning to reveal the function of reconsolidation, its mechanistic relationship to consolidation and its potential as a therapeutic target for the modification of memories.
Topics: Animals; Humans; Memory; Prefrontal Cortex; Transcranial Magnetic Stimulation
PubMed: 22280913
DOI: 10.1016/j.cub.2011.11.051 -
European Journal of Psychotraumatology 2022Background Trauma- and stress-related disorders, such as post-traumatic stress disorder (PTSD), are more common in females than in males. Sex hormones affect learning...
Background Trauma- and stress-related disorders, such as post-traumatic stress disorder (PTSD), are more common in females than in males. Sex hormones affect learning and emotional memory formation and may be associated with the development of PTSD. Most previous studies have indexed these hormones in isolation. To investigate associations of sex hormones and cortisol during memory consolidation on the development of intrusive memories. We employed an experimental trauma film paradigm in 61 healthy women and indexed salivary testosterone, progesterone, estradiol, and cortisol on day one and day two post experimental trauma exposure and their effects on intrusion frequency, distress, and vividness. Intrusive trauma memories were indexed by means of a diary in which participants documented intrusion frequency, distress, and vividness. Participants reported an average of 5.3 intrusions over the course of seven days (SD = 4.6, range 0-26). Progesterone, and estradiol indexed on day one predicted intrusion frequency, with higher progesterone and lower estradiol predicting more intrusive memories (-values AUC progesterone 0.01 and estradiol 0.02). There was no evidence for associations between hormone concentration indices on day two and intrusion outcomes. Further research on the roles of gonadal and adrenal hormones in trauma memory formation is needed to advance our efforts to understand their influence on PTSD development.
Topics: Estradiol; Female; Humans; Hydrocortisone; Male; Memory; Memory Consolidation; Progesterone
PubMed: 35386732
DOI: 10.1080/20008198.2022.2040818 -
Cell Reports Dec 2023How memories are organized in the brain influences whether they are remembered discretely versus linked with other experiences or whether generalized information is...
How memories are organized in the brain influences whether they are remembered discretely versus linked with other experiences or whether generalized information is applied to entirely novel situations. Here, we used scFLARE2 (single-chain fast light- and activity-regulated expression 2), a temporally precise tagging system, to manipulate mouse lateral amygdala neurons active during one of two 3 min threat experiences occurring close (3 h) or further apart (27 h) in time. Silencing scFLARE2-tagged neurons showed that two threat experiences occurring at distal times are dis-allocated to orthogonal engram ensembles and remembered discretely, whereas the same two threat experiences occurring in close temporal proximity are linked via co-allocation to overlapping engram ensembles. Moreover, we found that co-allocation mediates memory generalization applied to a completely novel stimulus. These results indicate that endogenous temporal evolution of engram ensemble neuronal excitability determines how memories are organized and remembered and that this would not be possible using conventional immediate-early gene-based tagging methods.
Topics: Mice; Animals; Memory; Fear; Neurons; Brain; Mental Recall
PubMed: 38103203
DOI: 10.1016/j.celrep.2023.113592 -
Current Opinion in Neurobiology Oct 2013It would be nice if we could talk about sleep and memory as if there were only one type of memory and one type of sleep. But this is far from the case. Sleep and memory... (Review)
Review
It would be nice if we could talk about sleep and memory as if there were only one type of memory and one type of sleep. But this is far from the case. Sleep and memory each comes in many forms, and furthermore, memories can go through multiple forms of post-encoding processing that must be individually addressed. Finally, sleep stages per se do not affect memories. Rather, the neuromodulatory and electrophysiological events that characterize these sleep stages must mediate sleep-dependent memory processing. In this review, we attempt to parse out the relative contributions and interactions of these often frustratingly complex systems.
Topics: Animals; Brain; Humans; Memory; Sleep
PubMed: 23618558
DOI: 10.1016/j.conb.2013.04.002 -
Neurobiology of Learning and Memory Sep 2018Memories are dynamic in nature. A cohesive representation of the world requires memories to be altered over time, linked with other memories and eventually integrated... (Review)
Review
Memories are dynamic in nature. A cohesive representation of the world requires memories to be altered over time, linked with other memories and eventually integrated into a larger framework of sematic knowledge. Although there is a considerable literature on how single memories are encoded, retrieved and updated, little is known about the mechanisms that govern memory linking, e.g., linking and integration of various memories across hours or days. In this review, we present evidence that specific memory allocation mechanisms, such as changes in CREB and intrinsic excitability, ensure memory storage in ways that facilitate effective recall and linking at a later time. Beyond CREB and intrinsic excitability, we also review a number of other phenomena with potential roles in memory linking.
Topics: Animals; Brain; Cortical Excitability; Cyclic AMP Response Element-Binding Protein; Humans; Memory; Mental Recall; Neuronal Plasticity; Neurons; Synapses; Time Factors
PubMed: 29496645
DOI: 10.1016/j.nlm.2018.02.021