scholarly journals Replay of cortical spiking sequences during human memory retrieval

Science ◽  
2020 ◽  
Vol 367 (6482) ◽  
pp. 1131-1134 ◽  
Author(s):  
Alex P. Vaz ◽  
John H. Wittig ◽  
Sara K. Inati ◽  
Kareem A. Zaghloul
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Medial Temporal Lobe ◽  
Single Unit ◽  
Temporal Order ◽  
Human Memory ◽  
Memory Encoding ◽  
Human Cortex ◽  
Past Experiences ◽  
Specific Sequences

Episodic memory retrieval is thought to rely on the replay of past experiences, yet it remains unknown how human single-unit activity is temporally organized during episodic memory encoding and retrieval. We found that ripple oscillations in the human cortex reflect underlying bursts of single-unit spiking activity that are organized into memory-specific sequences. Spiking sequences occurred repeatedly during memory formation and were replayed during successful memory retrieval, and this replay was associated with ripples in the medial temporal lobe. Together, these data demonstrate that human episodic memory is encoded by specific sequences of neural activity and that memory recall involves reinstating this temporal order of activity.

scholarly journals Episodic memory and common sense: how far apart?

2001 ◽  
Vol 356 (1413) ◽  
pp. 1505-1515 ◽  
Author(s):  
Endel Tulving
Keyword(s):  
Episodic Memory ◽  
Common Sense ◽  
Memory Retrieval ◽  
Critical Role ◽  
Human Memory ◽  
Memory Systems ◽  
Perceptual Information ◽  
Subjective Time ◽  
Retrieval Processes ◽  
Past Experiences

Research has revealed facts about human memory in general and episodic memory in particular that deviate from both common sense and previously accepted ideas. This paper discusses some of these deviations in light of the proceedings of The Royal Society's Discussion Meeting on episodic memory. Retrieval processes play a more critical role in memory than commonly assumed; people can remember events that never happened; and conscious thoughts about one's personal past can take two distinct forms—‘autonoetic’ remembering and ‘noetic’ knowing. The serial—dependent—independent (SPI) model of the relations among episodic, semantic and perceptual memory systems accounts for a number of puzzling phenomena, such as some amnesic patients' preserved recognition memory and their ability to learn new semantic facts, and holds that episodic remembering of perceptual information can occur only by virtue of its mediation through semantic memory. Although common sense endows many animals with the ability to remember their past experiences, as yet there is no evidence that humanlike episodic memory—defined in terms of subjective time, self, and autonoetic awareness—is present in any other species.

Lateralization of Prefrontal Activity during Episodic Memory Retrieval: Evidence for the Production-Monitoring Hypothesis

2003 ◽  
Vol 15 (2) ◽  
pp. 249-259 ◽  
Author(s):  
Roberto Cabeza ◽  
Jill K. Locantore ◽  
Nicole D. Anderson
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Medial Temporal Lobe ◽  
Item Recognition ◽  
Cued Recall ◽  
Anterior Cingulate ◽  
Episodic Retrieval ◽  
Context Recognition ◽  
Production Monitoring ◽  
The Right

We propose a new hypothesis concerning the lateralization of prefrontal cortex (PFC) activity during verbal episodic memory retrieval. The hypothesis states that the left PFC is differentially more involved in semantically guided information production than is the right PFC, and that the right PFC is differentially more involved in monitoring and verification than is the left PFC. This “production-monitoring hypothesis” differs from the existing “systematic-heuristic hypothesis,” which proposes that the left PFC is primarily involved in systematic retrieval operations, and the right PFC in heuristic retrieval operations. To compare the two hypotheses, we measured PFC activity using positron emission tomography (PET) during the performance of four episodic retrieval tasks: stem cued recall, associative cued recall, context recognition (source memory), and item recognition. Recall tasks emphasized production processes, whereas recognition tasks emphasized monitoring processes. Stem cued recall and context-recognition tasks underscored systematic operations, whereas associative cued recall and item-recognition tasks underscored heuristic operations. Consistent with the production-monitoring hypothesis, the left PFC was more activated for recall than for recognition tasks and the right PFC was more activated for recognition than for recall tasks. Inconsistent with the systematic-heuristic hypothesis, the left PFC was more activated for heuristic than for systematic tasks and the right PFC showed the converse result. Additionally, the study yielded activation differences outside the PFC. In agreement with a previous recall/recognition PET study, anterior cingulate, cerebellar, and striatal regions were more activated for recall than for recognition tasks, and the converse occurred for posterior parietal regions. A right medial temporal lobe region was more activated for stem cued recall and context recognition than for associative cued recall and item recognition, possibly reflecting perceptual integration. In sum, the results provide evidence for the production-monitoring hypothesis and clarify the role of different brain regions typically activated in PET and functional magnetic resonance imaging (fMRI) studies of episodic retrieval.

scholarly journals Behavioral evidence for memory replay of video episodes in macaque monkeys

2020 ◽  
Author(s):  
Shuzhen Zuo ◽  
Lei Wang ◽  
Junghan Shin ◽  
Yudian Cai ◽  
Sang Wan Lee ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Rhesus Monkeys ◽  
Temporal Order ◽  
Irrelevant Information ◽  
Macaque Monkeys ◽  
The Past ◽  
Non Linear ◽  
Temporal Order Judgement ◽  
Behavioral Evidence ◽  
Past Experiences

ABSTRACTHumans recall the past by replaying fragments of events temporally. Here, we demonstrate a similar effect in macaques. We trained six rhesus monkeys with a temporal-order judgement (TOJ) task and collected 5000 TOJ trials. In each trial, they watched a naturalistic video of about 10 s comprising two across-context clips, and after a 2-s delay, performed TOJ between two frames from the video. The monkeys apply a non-linear forward, time-compressed replay mechanism during the temporal-order judgement. In contrast with humans, such compression of replay is however not sophisticated enough to allow them to skip over irrelevant information by compressing the encoded video globally. We also reveal that the monkeys detect event contextual boundaries and such detection facilitates recall by an increased rate of information accumulation. Demonstration of a time-compressed, forward replay like pattern in the macaque monkeys provides insights into the evolution of episodic memory in our lineage.Impact StatementMacaque monkeys temporally compress past experiences and use a forward-replay mechanism during judgment of temporal-order between episodes.

scholarly journals Increased task-dependent functional connectivity by stimulation of the hippocampal network predicts memory enhancement

2019 ◽  
Author(s):  
Kristen N. Warren ◽  
Molly S. Hermiller ◽  
Aneesha S. Nilakantan ◽  
Joel L. Voss
Keyword(s):  
Functional Connectivity ◽  
Episodic Memory ◽  
Memory Retrieval ◽  
Medial Temporal Lobe ◽  
Network Connectivity ◽  
Network Control ◽  
Retrieval Task ◽  
Memory Processing ◽  
Hippocampal Network ◽  
Hippocampal Networks

AbstractSuccessful episodic memory involves dynamic increases in the coordination of activity across distributed hippocampal networks, including the posterior-medial network (PMN) and the anterior-temporal network (ATN). We tested whether this up-regulation of functional connectivity during memory processing can be enhanced within hippocampal networks by noninvasive stimulation, and whether such task-dependent connectivity enhancement predicts episodic memory improvement. Participants received stimulation targeting either the PMN or an out-of-network control location. We compared the effects of stimulation on fMRI connectivity measured during an autobiographical memory retrieval task versus during rest within the PMN and the ATN. PMN-targeted stimulation significantly increased connectivity during memory retrieval versus rest within the PMN. This effect was not observed in the ATN, or in either network due to control out-of-network stimulation. Task-dependent increases in connectivity due to PMN-targeted stimulation within the medial temporal lobe predicted improved performance of a separate episodic memory test. It is therefore possible to enhance the task-dependent regulation of hippocampal network connectivity that supports memory processing using noninvasive stimulation.

Individual Differences in Value-Directed Remembering

2019 ◽  
Author(s):  
Blake L. Elliott ◽  
Samuel M. McClure ◽  
Gene Arnold Brewer
Keyword(s):  
Working Memory ◽  
Individual Differences ◽  
Episodic Memory ◽  
Structural Equation ◽  
Working Memory Capacity ◽  
Human Memory ◽  
Memory Capacity ◽  
Equation Modeling ◽  
Memory Encoding ◽  
Capacity Limits

Prioritized encoding and retrieval of valuable information is an essential component of human memory due to capacity limits. Individual differences in value-directed encoding may derive from variability in stimulus valuation, memory encoding, or from strategic abilities related to maintenance in working memory. We collected multiple cognitive ability measures to test whether variation in episodic memory, working memory capacity, or both predict differences in value-directed remembering among a large sample of participants (n=205). Confirmatory factor analysis and structural equation modeling was used to assess the contributions of episodic and working memory to value sensitivity in value-directed remembering tasks. Episodic memory ability, but not working memory capacity, was predictive of value-directed remembering. These results suggest that cognitive processes may be differentially related to value-based memory encoding.

scholarly journals Episodic memory-related activation in schizophrenia: meta-analysis

2005 ◽  
Vol 187 (6) ◽  
pp. 500-509 ◽  
Author(s):  
Amélie M. Achim ◽  
Martin Lepage
Keyword(s):  
Episodic Memory ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Meta Analysis ◽  
Temporal Cortex ◽  
Neural Correlates ◽  
Brain Regions ◽  
Group Differences ◽  
Memory Encoding ◽  
The Brain

BackgroundNumerous studies have examined the neural correlates of episodic memory deficits in schizophrenia, yielding both consistencies and discrepancies in the reported patterns of results.AimsTo identify in schizophrenia the brain regions in which activity is consistently abnormal across imaging studies of memory.MethodData from 18 studies meeting the inclusion criteria were combined using a recently developed quantitative meta-analytic approach.ResultsRegions of consistent differential activation between groups were observed in the left inferior prefrontal cortex, medial temporal cortex bilaterally, left cerebellum, and in other prefrontal and temporal lobe regions. Subsequent analyses explored memory encoding and retrieval separately and identified between-group differences in specific prefrontal and medial temporal lobe regions.ConclusionsBeneath the apparent heterogeneity of published findings on schizophrenia and memory, a consistent and robust pattern of group differences is observed as a function of memory processes.

scholarly journals Age-Related Compensatory Reconfiguration of PFC Connections during Episodic Memory Retrieval

2020 ◽  
Author(s):  
Lifu Deng ◽  
Mathew L Stanley ◽  
Zachary A Monge ◽  
Erik A Wing ◽  
Benjamin R Geib ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Medial Temporal Lobe ◽  
Memory Performance ◽  
Functional Integration ◽  
Brain Network ◽  
Age Related ◽  
Connectivity Patterns ◽  
The Brain ◽  
Related Increase

Abstract During demanding cognitive tasks, older adults (OAs) frequently show greater prefrontal cortex (PFC) activity than younger adults (YAs). This age-related increase in PFC activity is often associated with enhanced cognitive performance, suggesting functional compensation. However, the brain is a complex network of interconnected regions, and it is unclear how network connectivity of PFC regions differs for OAs versus YAs. To investigate this, we examined the age-related difference on the functional brain networks mediating episodic memory retrieval. YAs and OAs participants encoded and recalled visual scenes, and age-related differences in network topology during memory retrieval were investigated as a function of memory performance. We measured both changes in functional integration and reconfiguration in connectivity patterns. The study yielded three main findings. First, PFC regions were more functionally integrated with the rest of the brain network in OAs. Critically, this age-related increase in PFC integration was associated with better retrieval performance. Second, PFC regions showed stronger performance-related reconfiguration of connectivity patterns in OAs. Finally, the PFC reconfiguration increases in OAs tracked reconfiguration reductions in the medial temporal lobe (MTL)—a core episodic memory region, suggesting that PFC connectivity in OAs may be compensating for MTL deficits.

Imaging Cognition II: An Empirical Review of 275 PET and fMRI Studies

2000 ◽  
Vol 12 (1) ◽  
pp. 1-47 ◽  
Author(s):  
Roberto Cabeza ◽  
Lars Nyberg
Keyword(s):  
Working Memory ◽  
Episodic Memory ◽  
Semantic Memory ◽  
Memory Retrieval ◽  
Procedural Memory ◽  
Spatial Problem ◽  
Memory Encoding ◽  
Functional Neuroanatomy ◽  
Activation Patterns ◽  
Space Motion

Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have been extensively used to explore the functional neuroanatomy of cognitive functions. Here we review 275 PET and fMRI studies of attention (sustained, selective, Stroop, orientation, divided), perception (object, face, space/motion, smell), imagery (object, space/ motion), language (written/spoken word recognition, spoken/ no spoken response), working memory (verbal/numeric, object, spatial, problem solving), semantic memory retrieval (categorization, generation), episodic memory encoding (verbal, object, spatial), episodic memory retrieval (verbal, nonverbal, success, effort, mode, context), priming (perceptual, conceptual), and procedural memory (conditioning, motor, and nonmotor skill learning). To identify consistent activation patterns associated with these cognitive operations, data from 412 contrasts were summarized at the level of cortical Brodmann's areas, insula, thalamus, medial-temporal lobe (including hippocampus), basal ganglia, and cerebellum. For perception and imagery, activation patterns included primary and secondary regions in the dorsal and ventral pathways. For attention and working memory, activations were usually found in prefrontal and parietal regions. For language and semantic memory retrieval, typical regions included left prefrontal and temporal regions. For episodic memory encoding, consistently activated regions included left prefrontal and medial-temporal regions. For episodic memory retrieval, activation patterns included prefrontal, medial-temporal, and posterior midline regions. For priming, deactivations in prefrontal (conceptual) or extrastriate (perceptual) regions were consistently seen. For procedural memory, activations were found in motor as well as in non-motor brain areas. Analysis of regional activations across cognitive domains suggested that several brain regions, including the cerebellum, are engaged by a variety of cognitive challenges. These observations are discussed in relation to functional specialization as well as functional integration.

scholarly journals Effects of semantic relatedness on recall of stimuli preceding emotional oddballs

2008 ◽  
Vol 14 (4) ◽  
pp. 620-628 ◽  
Author(s):  
RYAN M. SMITH ◽  
DAVID Q. BEVERSDORF
Keyword(s):  
Free Recall ◽  
Episodic Memory ◽  
Semantic Memory ◽  
Medial Temporal Lobe ◽  
Semantic Information ◽  
Negative Emotion ◽  
Semantic Relatedness ◽  
Stimulus Presentation ◽  
Interconnected Systems ◽  
Memory Encoding

Semantic and episodic memory networks function as highly interconnected systems, both relying on the hippocampal/medial temporal lobe complex (HC/MTL). Episodic memory encoding triggers the retrieval of semantic information, serving to incorporate contextual relationships between the newly acquired memory and existing semantic representations. While emotional material augments episodic memory encoding at the time of stimulus presentation, interactions between emotion and semantic memory that contribute to subsequent episodic recall are not well understood. Using a modified oddball task, we examined the modulatory effects of negative emotion on semantic interactions with episodic memory by measuring the free-recall of serially presented neutral or negative words varying in semantic relatedness. We found increased free-recall for words related to and preceding emotionally negative oddballs, suggesting that negative emotion can indirectly facilitate episodic free-recall by enhancing semantic contributions during encoding. Our findings demonstrate the ability of emotion and semantic memory to interact to mutually enhance free-recall. (JINS, 2008, 14, 620–628.)

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