scholarly journals The neural basis of episodic memory: evidence from functional neuroimaging

2002 ◽  
Vol 357 (1424) ◽  
pp. 1097-1110 ◽  
Author(s):  
Michael D. Rugg ◽  
Leun J. Otten ◽  
Richard N. A. Henson
Keyword(s):  
Episodic Memory ◽  
Neural Activity ◽  
Functional Neuroimaging ◽  
Neural Basis ◽  
Retrieval Task ◽  
Cortical Level ◽  
Episodic Information ◽  
Episodic Encoding ◽  
Episodic Memories ◽  
Anterior Prefrontal Cortex

We review some of our recent research using functional neuroimaging to investigate neural activity supporting the encoding and retrieval of episodic memories, that is, memories for unique events. Findings from studies of encoding indicate that, at the cortical level, the regions responsible for the effective encoding of a stimulus event as an episodic memory include some of the regions that are also engaged to process the event ‘online’. Thus, it appears that there is no single cortical site or circuit responsible for episodic encoding. The results of retrieval studies indicate that successful recollection of episodic information is associated with activation of lateral parietal cortex, along with more variable patterns of activity in dorsolateral and anterior prefrontal cortex. Whereas parietal regions may play a part in the representation of retrieved information, prefrontal areas appear to support processes that act on the products of retrieval to align behaviour with the demands of the retrieval task.

scholarly journals Autobiographically Significant Concepts: More Episodic than Semantic in Nature? An Electrophysiological Investigation of Overlapping Types of Memory

2015 ◽  
Vol 27 (1) ◽  
pp. 57-72 ◽  
Author(s):  
Louis Renoult ◽  
Patrick S. R. Davidson ◽  
Erika Schmitz ◽  
Lillian Park ◽  
Kenneth Campbell ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Semantic Memory ◽  
Recognition Task ◽  
Positive Component ◽  
Late Positive Component ◽  
Episodic Information ◽  
Semantic Concepts ◽  
N400 Component ◽  
Episodic Memories ◽  
Highly Correlated

A common assertion is that semantic memory emerges from episodic memory, shedding the distinctive contexts associated with episodes over time and/or repeated instances. Some semantic concepts, however, may retain their episodic origins or acquire episodic information during life experiences. The current study examined this hypothesis by investigating the ERP correlates of autobiographically significant (AS) concepts, that is, semantic concepts that are associated with vivid episodic memories. We inferred the contribution of semantic and episodic memory to AS concepts using the amplitudes of the N400 and late positive component, respectively. We compared famous names that easily brought to mind episodic memories (high AS names) against equally famous names that did not bring such recollections to mind (low AS names) on a semantic task (fame judgment) and an episodic task (recognition memory). Compared with low AS names, high AS names were associated with increased amplitude of the late positive component in both tasks. Moreover, in the recognition task, this effect of AS was highly correlated with recognition confidence. In contrast, the N400 component did not differentiate the high versus low AS names but, instead, was related to the amount of general knowledge participants had regarding each name. These results suggest that semantic concepts high in AS, such as famous names, have an episodic component and are associated with similar brain processes to those that are engaged by episodic memory. Studying AS concepts may provide unique insights into how episodic and semantic memory interact.

Transient Disruption of Ventrolateral Prefrontal Cortex During Verbal Encoding Affects Subsequent Memory Performance

2005 ◽  
Vol 94 (1) ◽  
pp. 688-698 ◽  
Author(s):  
Itamar Kahn ◽  
Alvaro Pascual-Leone ◽  
Hugo Theoret ◽  
Felipe Fregni ◽  
Dav Clark ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Episodic Memory ◽  
Phonological Processing ◽  
Functional Neuroimaging ◽  
Memory Performance ◽  
Single Pulse ◽  
Stimulus Onset ◽  
Ventrolateral Prefrontal Cortex ◽  
Episodic Encoding ◽  
Functional Shift

Episodic memory supports conscious remembrance of everyday experience. Prior functional neuroimaging data indicate that episodic encoding during phonological task performance is correlated with activation in bilateral posterior ventrolateral prefrontal cortex (pVLPFC), although uncertainty remains regarding whether these prefrontal regions make necessary contributions to episodic memory formation. Using functional MRI data to guide application of single-pulse transcranial magnetic stimulation (spTMS), this study examined the necessity of left and right pVLPFC for episodic encoding (as expressed through subsequent memory performance). To assess the timing of critical computations, pVLPFC function was transiently disrupted at different poststimulus onset times while subjects made syllable decisions about visually presented familiar and unfamiliar words; subsequent memory for these stimuli was measured. Results revealed that left pVLPFC disruption during encoding of familiar words impaired subsequent memory, expressed as a decline in recognition confidence, with disruption being maximal at 380 ms after stimulus onset. In contrast, right pVLPFC disruption facilitated subsequent memory for familiar words, expressed as an increase in medium confidence recognition, with this facilitation being maximal at 380 ms. Finally, phonological (syllable) decision accuracy was facilitated by right pVLPFC disruption, with this effect being maximal at 340 ms, but was unaffected by left pVLPFC disruption. These findings suggest that left pVLPFC mechanisms onset between 300 and 400 ms during phonological processing of words, with these mechanisms appearing necessary for effective episodic encoding. In contrast, disruption of correlated mechanisms in right pVLPFC facilitates encoding, perhaps by inducing a functional shift in the mechanisms engaged during learning.

Composition and replay of mnemonic sequences: The contributions of REM and slow-wave sleep to episodic memory

2013 ◽  
Vol 36 (6) ◽  
pp. 610-611 ◽  
Author(s):  
Sen Cheng ◽  
Markus Werning
Keyword(s):  
Episodic Memory ◽  
Eye Movement ◽  
Slow Wave ◽  
Rem Sleep ◽  
Neural Activity ◽  
Slow Wave Sleep ◽  
Place Cells ◽  
Object Representations ◽  
Episodic Memories ◽  
Gamma Band Oscillations

AbstractWe propose that rapid eye movement (REM) and slow-wave sleep contribute differently to the formation of episodic memories. REM sleep is important for building up invariant object representations that eventually recur to gamma-band oscillations in the neocortex. In contrast, slow-wave sleep is more directly involved in the consolidation of episodic memories through replay of sequential neural activity in hippocampal place cells.

scholarly journals Failure to reactivate salient episodic information during indirect and direct tests of memory retrieval

2017 ◽  
Author(s):  
Mason H. Price ◽  
Jeffrey D. Johnson
Keyword(s):  
Boundary Condition ◽  
Episodic Memory ◽  
Neural Activity ◽  
Memory Retrieval ◽  
Conscious Awareness ◽  
Episodic Retrieval ◽  
Flicker Frequency ◽  
Test Items ◽  
Episodic Information ◽  
Cortical Regions

ABSTRACTSeveral fMRI and EEG studies have demonstrated that successful episodic retrieval is accompanied by the reactivation of cortical regions that were active during encoding. These findings are consistent with influential models of episodic memory that posit that conscious retrieval (recollection) relies on hippocampally-mediated cortical reinstatement. Evidence of reactivation corresponding to episodic information that is beyond conscious awareness at the time of memory retrieval, however, is limited. A recent exception is from an EEG study by Wimber, Maaβ, Staudigl, Richardson-Klavehn, and Hanslmayr (2012) in which words were encoded in the context of highly salient visual flicker entrainment and then presented at retrieval in the absence of any flicker. In that study, coherent (phase-locked) neural activity was observed at the corresponding entrained frequencies during retrieval, consistent with the notion that encoding representations were reactivated. Given the important implications of unconscious reactivation to past findings and the modeling literature, the current study set out to provide a direct replication of the previous study. Additionally, an attempt was made to extend such findings to intentional retrieval by acquiring EEG while subjects were explicitly asked to make memory judgments about the flicker frequency from encoding. Throughout a comprehensive set of analyses, the current study consistently failed to demonstrate evidence for unconscious reactivation, and instead provided support that test items were indistinguishable according to their prior encoding context. The findings thus establish an important boundary condition for the involvement of cortical reinstatement in episodic memory.

scholarly journals Reinstatement of Event Details during Episodic Simulation in the Hippocampus

2019 ◽  
Vol 30 (4) ◽  
pp. 2321-2337 ◽  
Author(s):  
Preston P Thakral ◽  
Kevin P Madore ◽  
Donna Rose Addis ◽  
Daniel L Schacter
Keyword(s):  
Episodic Memory ◽  
Subjective Experience ◽  
Functional Neuroimaging ◽  
Specific Information ◽  
Episodic Retrieval ◽  
The People ◽  
Episodic Information ◽  
Episodic Simulation ◽  
Pattern Similarity ◽  
Neuroimaging Study

Abstract According to the constructive episodic simulation hypothesis, episodic simulation (i.e., imagining specific novel future episodes) draws on some of the same neurocognitive processes that support episodic memory (i.e., recalling specific past episodes). Episodic retrieval supports the ability to simulate future experiences by providing access to episodic details (e.g., the people and locations that comprise memories) that can be recombined in new ways. In the current functional neuroimaging study, we test this hypothesis by examining whether the hippocampus, a region implicated in the reinstatement of episodic information during memory, supports reinstatement of episodic information during simulation. Employing a multivoxel pattern similarity analysis, we interrogated the similarity between hippocampal neural patterns during memory and simulation at the level of individual event details. Our findings indicate that the hippocampus supports the reinstatement of detail-specific information from episodic memory during simulation, with the level of reinstatement contributing to the subjective experience of simulated details.

scholarly journals Causal evidence for mnemonic metacognition in human precuneus

2018 ◽  
Author(s):  
Qun Ye ◽  
Futing Zou ◽  
Hakwan Lau ◽  
Yi Hu ◽  
Sze Chai Kwok
Keyword(s):  
Prefrontal Cortex ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Parietal Lobe ◽  
Functional Neuroimaging ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Brain Regions ◽  
Neural Basis ◽  
Anterior Prefrontal Cortex

AbstractMetacognition is the capacity to introspectively monitor and control one’s own cognitive processes. Previous anatomical and functional neuroimaging findings implicated the important role of precuneus in metacognition processing, especially during mnemonic tasks. However, the issue of whether this medial parietal cortex is a domain-specific region that supports mnemonic metacognition remains controversial. Here, we focally disrupted this parietal area with repetitive transcranial magnetic stimulation in healthy participants of both sexes, seeking to ascertain its functional necessity for metacognition for memory versus perceptual decisions. Perturbing the precuneal activity impaired the metacognitive efficiency selectively in the memory judgment of temporal-order, but not in perceptual discrimination. Moreover, the correlation in individuals’ metacognitive efficiency between the domains disappeared when the precuneus was perturbed. Together with the previous finding that lesion to the anterior prefrontal cortex impairs perceptual but not mnemonic metacognition, we double dissociated the macro-anatomical underpinnings for the two kinds of metacognitive capacity in an interconnected network of brain regions.SIGNIFICANCE STATEMENTTheories on the neural basis of metacognition have thus far largely centered on the role of prefrontal cortex. Here we refined the theoretical framework through characterizing a unique precuneal involvement in mnemonic metacognition with a noninvasive but inferentially powerful method: transcranial magnetic stimulation. By quantifying meta-cognitive efficiency across two distinct domains (memory vs. perception) that are matched for stimulus characteristics, we reveal an instrumental – and highly selective – role of the precuneus in mnemonic metacognition. These causal evidence corroborate ample clinical reports that parietal lobe lesions often produce inaccurate self-reports of confidence in memory recollection and establish that the precuneus as a nexus for the introspective ability to evaluate the success of memory judgment in humans.

scholarly journals Electrophysiological studies of identifying and modulating the preparatory strategic processes involved in episodic memory retrieval

2018 ◽  
Author(s):  
◽  
Mason H. Price
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Task Demands ◽  
Event Related Potential ◽  
Oscillatory Activity ◽  
Retrieval Task ◽  
Retrieval Cues ◽  
Starting Point ◽  
Episodic Memories ◽  
Cue Processing

Successful retrieval of episodic memories has been shown to depend on the overlap between the processes engaged during encoding and those re-engaged during retrieval. The ability to strategically adapt cue processing to maximize this overlap, sometimes referred to as “retrieval orientation”, has been supported by numerous studies employing electroencephalography (EEG), which demonstrate differences according to the class of memories being sought. However, research in this domain has largely focused on event-related potential (ERP) effects of sustained amplitude that occur after the onset of retrieval cues, thereby failing to indicate whether such effects might be engaged in a preparatory manner before cue onset. Here, we describe two experiments that addressed this issue by employing an analysis approach focusing on the pre-stimulus period of retrieval test trials and capitalizing on the increased sensitivity of multivariate pattern analysis (MVPA) of oscillatory activity. Experiment 1 established evidence of a preparatory form of retrieval orienting and examined the potential fluctuation versus stability of such processing. Experiment 2 attempted to directly modulate the engagement of orienting processes by parametrically manipulating the extent to which responses during the retrieval task are speeded. By novelly quantifying the relationship between multivariate neural correlates of retrieval orientation and behavioral measures of performance, and testing how orienting might be flexibly adjusted to meet task demands, the current project serves as a starting point for developing techniques aimed at improving episodic memory retrieval through strategic control.

scholarly journals Theories of episodic memory

2001 ◽  
Vol 356 (1413) ◽  
pp. 1395-1408 ◽  
Author(s):  
Andrew R. Mayes ◽  
Neil Roberts
Keyword(s):  
Episodic Memory ◽  
Medial Temporal Lobe ◽  
Functional Neuroimaging ◽  
Memory Storage ◽  
Visual Object ◽  
Medial Temporal Lobes ◽  
Temporal Lobes ◽  
Episodic Information ◽  
Encoding And Retrieval

Theories of episodic memory need to specify the encoding (representing), storage, and retrieval processes that underlie this form of memory and indicate the brain regions that mediate these processes and how they do so. Representation and re–representation (retrieval) of the spatiotemporally linked series of scenes, which constitute an episode, are probably mediated primarily by those parts of the posterior neocortex that process perceptual and semantic information. However, some role of the frontal neocortex and medial temporal lobes in representing aspects of context and high–level visual object information at encoding and retrieval cannot currently be excluded. Nevertheless, it is widely believed that the frontal neocortex is mainly involved in coordinating episodic encoding and retrieval and that the medial temporal lobes store aspects of episodic information. Establishing where storage is located is very difficult and disagreement remains about the role of the posterior neocortex in episodic memory storage. One view is that this region stores all aspects of episodic memory ab initio for as long as memory lasts. This is compatible with evidence that the amygdala, basal forebrain, and midbrain modulate neocortical storage. Another view is that the posterior neocortex only gradually develops the ability to store some aspects of episodic information as a function of rehearsal over time and that this information is initially stored by the medial temporal lobes. A third view is that the posterior neocortex never stores these aspects of episodic information because the medial temporal lobes store them for as long as memory lasts in an increasingly redundant fashion. The last two views both postulate that the medial temporal lobes initially store contextual markers that serve to cohere featural information stored in the neocortex. Lesion and functional neuroimaging evidence still does not clearly distinguish between these views. Whether the feeling that an episodic memory is familiar depends on retrieving an association between a retrieved episode and this feeling, or by an attribution triggered by a priming process, is unclear. Evidence about whether the hippocampus and medial temporal lobe cortices play different roles in episodic memory is conflicting. Identifying similarities and differences between episodic memory and both semantic memory and priming will require careful componential analysis of episodic memory.

scholarly journals Encoding Processes during Retrieval Tasks

2001 ◽  
Vol 13 (3) ◽  
pp. 406-415 ◽  
Author(s):  
Randy L. Buckner ◽  
Mark E. Wheeler ◽  
Margaret A. Sheridan
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Memory Encoding ◽  
Imaging Data ◽  
Repeated Testing ◽  
Retrieval Task ◽  
Partial Explanation ◽  
New Words ◽  
Episodic Encoding ◽  
Incidental Encoding

Episodic memory encoding is pervasive across many kinds of task and often arises as a secondary processing effect in tasks that do not require intentional memorization. To illustrate the pervasive nature of information processing that leads to epeisodic encoding, a form of incidental encoding was explored based on the “Testing” phenomenon: The incidental-encoding task was an episodic memory retrieval task. Behavioral data showed that performing a memory retrieval task was as effedctive as intentional instructions at promoting episodic encoding. During fMRI imaging, subjedcts veiewed old and new words adn indicated whether they remembered them. Relevant to encoding, the fate of the new words was examined using a second, surprise test of recognition after the imaging session, fMRI analysis of those new words that were later remembered revealed greater activity in left frontal regions than those that were later forgotten-the same pattern of results as previously observed for traditional incidental and intentional episodic encoding tasks. This finding may offer a partial explanation for why repeated testing improves memory performance. Furthermore, the observation of correlates of episodic memory encoding during retrieval tasks challenges some interpretations that aris from direct comparisons between: encoding tasks and “retrieval tasks” in imaging data. Encoding processes and their neural correlates may arise in many tasks, even those nominally labeled as retrieval tasks by the experimenter.

Large Scale Neurocognitive Networks Underlying Episodic Memory

2000 ◽  
Vol 12 (1) ◽  
pp. 163-173 ◽  
Author(s):  
Lars Nyberg ◽  
Jonas Persson ◽  
Reza Habib ◽  
Endel Tulving ◽  
Anthony R. McIntosh ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Large Scale ◽  
Functional Neuroimaging ◽  
Brain Activity ◽  
Activity Patterns ◽  
Brain Regions ◽  
Target Density ◽  
Functional Connections ◽  
Positron Emission ◽  
Episodic Encoding

Large-scale networks of brain regions are believed to mediate cognitive processes, including episodic memory. Analyses of regional differences in brain activity, measured by functional neuroimaging, have begun to identify putative components of these networks. To more fully characterize neurocognitive networks, however, it is necessary to use analytical methods that quantify neural network interactions. Here, we used positron emission tomography (PET) to measure brain activity during initial encoding and subsequent recognition of sentences and pictures. For each type of material, three recognition conditions were included which varied with respect to target density (0%, 50%, 100%). Analysis of large-scale activity patterns identified a collection of foci whose activity distinguished the processing of sentences vs. pictures. A second pattern, which showed strong prefrontal cortex involvement, distinguished the type of cognitive process (encoding or retrieval). For both pictures and sentences, the manipulation of target density was associated with minor activation changes. Instead, it was found to relate to systematic changes of functional connections between material-specific regions and several other brain regions, including medial temporal, right prefrontal and parietal regions. These findings provide evidence for large-scale neural interactions between material-specific and process-specific neural substrates of episodic encoding and retrieval.

Sign in / Sign up

Export Citation Format

Share Document