scholarly journals Information recovery following a retrospective cue decreases with time

2019 ◽  
Author(s):  
Asal Nouri ◽  
Edward F. Ester
Keyword(s):  
Partial Recovery ◽  
Alpha Band ◽  
Information Recovery ◽  
Active Memory ◽  
Neural Representations ◽  
Memory Traces ◽  
Memory Store ◽  
Memory Representations ◽  
Additional Memory ◽  
Temporal Degradation

AbstractWorking memory (WM) performance can be enhanced by an informative cue presented during storage. This effect, termed a retrocue benefit, can be used to explore how observers prioritize information stored in WM to guide behavior. Recent studies have demonstrated that neural representations of task-relevant memoranda are strengthened following the appearance of a retrocue, suggesting that participants can consult alternative information stores to supplement active memory traces. Here, we sought to better understand the nature of these memory store(s) by asking whether they are subject to the same temporal degradation seen in active memory representations. We reconstructed and quantified representations of remembered positions from alpha-band EEG activity recorded while participants performed a retrospectively cued spatial WM task, and varied the temporal interval separating the encoding display and retrocue. Although we observed a partial recovery of location information in all cue conditions, the magnitude of recovery was linearly and inversely related to the timing of the retrocue. This suggests that participants’ ability to supplement active memory representations with information from additional memory stores is not static: the information maintained in these stores may be subject to temporal degredation, or the stores themselves may become more difficult to access with time.

Perception: A Model Comprising Two Modes of Consciousness

1979 ◽  
Vol 49 (2) ◽  
pp. 431-444 ◽  
Author(s):  
Carl G. Aurell
Keyword(s):  
Space Perception ◽  
Human Perception ◽  
Conscious Awareness ◽  
Subliminal Perception ◽  
Sensory Data ◽  
Memory Store ◽  
Memory Representations ◽  
Ambiguous Stimuli

A model of human perception is proposed in which conscious awareness is assumed to be the result of two separate mechanisms each involving consciousness, one outer, sensori-produced, and one inner, conceptual. By mediation of flexible memory representations the sensory data of the outer consciousness give rise to a matched “copy” in the inner consciousness which conceptually organizes the former and also serves as input to the memory store. The model is applied to some perceptual problems in vision such as ambiguous stimuli, subjective contours, space perception, a case of metacontrast, and subliminal perception.

Asymmetries in the Processing of Vowel Height

2012 ◽  
Vol 55 (3) ◽  
pp. 903-918 ◽  
Author(s):  
Mathias Scharinger ◽  
Philip J. Monahan ◽  
William J. Idsardi
Keyword(s):  
Speech Perception ◽  
Source Parameters ◽  
Dipole Source ◽  
Neutral Position ◽  
Distinctive Features ◽  
Neural Representations ◽  
Memory Representations ◽  
Specific Position ◽  
Phonetic Features

Purpose Speech perception can be described as the transformation of continuous acoustic information into discrete memory representations. Therefore, research on neural representations of speech sounds is particularly important for a better understanding of this transformation. Speech perception models make specific assumptions regarding the representation of mid vowels (e.g., [ɛ]) that are articulated with a neutral position in regard to height. One hypothesis is that their representation is less specific than the representation of vowels with a more specific position (e.g., [æ]). Method In a magnetoencephalography study, we tested the underspecification of mid vowel in American English. Using a mismatch negativity (MMN) paradigm, mid and low lax vowels ([ɛ]/[æ]), and high and low lax vowels ([ i ]/[æ]), were opposed, and M100/N1 dipole source parameters as well as MMN latency and amplitude were examined. Results Larger MMNs occurred when the mid vowel [ɛ] was a deviant to the standard [æ], a result consistent with less specific representations for mid vowels. MMNs of equal magnitude were elicited in the high–low comparison, consistent with more specific representations for both high and low vowels. M100 dipole locations support early vowel categorization on the basis of linguistically relevant acoustic–phonetic features. Conclusion We take our results to reflect an abstract long-term representation of vowels that do not include redundant specifications at very early stages of processing the speech signal. Moreover, the dipole locations indicate extraction of distinctive features and their mapping onto representationally faithful cortical locations (i.e., a feature map).

scholarly journals Excitatory TMS Boosts Memory Representations

2018 ◽  
Author(s):  
Wei-Chun Wang ◽  
Erik A. Wing ◽  
David L.K. Murphy ◽  
Bruce M. Luber ◽  
Sarah H. Lisanby ◽  
...  
Keyword(s):  
Cognitive Enhancement ◽  
Functional Neuroimaging ◽  
Brain Activity ◽  
Neural Mechanisms ◽  
Temporal Memory ◽  
Memory Functioning ◽  
Neural Representations ◽  
Memory Representations ◽  
Science Investigations ◽  
Univariate Analyses

AbstractBrain stimulation technologies have seen increasing application in basic science investigations, specifically towards the goal of improving memory functioning. However, proposals concerning the neural mechanisms underlying cognitive enhancement often rely on simplified notions of excitation and, most applications examining the effects of transcranial magnetic stimulation (TMS) on functional neuroimaging measures have been limited to univariate analyses of brain activity. We present here analyses using representational similarity analysis (RSA) and encoding-retrieval similarity (ERS) analysis in order to quantify the effect of TMS on memory representations. To test whether an increase in local excitability in PFC can have measurable influences on upstream representations in earlier temporal memory regions, we compared 1Hz and 5Hz stimulation to the left dorsolateral PFC. We found that 10 minutes of 5Hz rTMS, relative to 1Hz, had multiple effects on neural representations: 1) greater RSA during both encoding and retrieval, 2) greater ERS across all items, and, critically, 3) increasing ERS in MTL with increasing univariate activity in DLPFC, and greater functional connectivity for hits than misses between these regions. These results provide the first evidence of rTMS enhancing semantic representations and strengthen the idea that rTMS may affect the reinstatement of previously experienced events in upstream regions.

scholarly journals Mnemonic prediction errors promote detailed memories

2021 ◽  
Vol 28 (11) ◽  
pp. 422-434
Author(s):  
Oded Bein ◽  
Natalie A. Plotkin ◽  
Lila Davachi
Keyword(s):  
Memory Trace ◽  
Theoretical Models ◽  
Item Memory ◽  
Prediction Errors ◽  
Memory Enhancement ◽  
Object A ◽  
Memory Traces ◽  
Memory Representations ◽  
Memory Advantage ◽  
Violated Expectations

When our experience violates our predictions, it is adaptive to update our knowledge to promote a more accurate representation of the world and facilitate future predictions. Theoretical models propose that these mnemonic prediction errors should be encoded into a distinct memory trace to prevent interference with previous, conflicting memories. We investigated this proposal by repeatedly exposing participants to pairs of sequentially presented objects (A → B), thus evoking expectations. Then, we violated participants’ expectations by replacing the second object in the pairs with a novel object (A → C). The following item memory test required participants to discriminate between identical old items and similar lures, thus testing detailed and distinctive item memory representations. In two experiments, mnemonic prediction errors enhanced item memory: Participants correctly identified more old items as old when those items violated expectations during learning, compared with items that did not violate expectations. This memory enhancement for C items was only observed when participants later showed intact memory for the related A → B pairs, suggesting that strong predictions are required to facilitate memory for violations. Following up on this, a third experiment reduced prediction strength prior to violation and subsequently eliminated the memory advantage of violations. Interestingly, mnemonic prediction errors did not increase gist-based mistakes of identifying old items as similar lures or identifying similar lures as old. Enhanced item memory in the absence of gist-based mistakes suggests that violations enhanced memory for items’ details, which could be mediated via distinct memory traces. Together, these results advance our knowledge of how mnemonic prediction errors promote memory formation.

scholarly journals Narratives as Networks: Predicting Memory from the Structure of Naturalistic Events

2021 ◽  
Author(s):  
Hongmi Lee ◽  
Janice Chen
Keyword(s):  
Memory Consolidation ◽  
Human Life ◽  
Discrete Events ◽  
Cortical Areas ◽  
Neural Representations ◽  
Causal Connections ◽  
Fmri Study ◽  
Memory Representations ◽  
Event Boundary ◽  
With Memory

ABSTRACTHuman life consists of a multitude of diverse and interconnected events. However, extant research has focused on how humans segment and remember discrete events from continuous input, with far less attention given to how the structure of connections between events impacts memory. We conducted an fMRI study in which subjects watched and recalled a series of realistic audiovisual narratives. By transforming narratives into networks of events, we found that more central events—those with stronger semantic or causal connections to other events—were better remembered. During encoding, central events evoked larger hippocampal event boundary responses associated with memory consolidation. During recall, high centrality predicted stronger activation in cortical areas involved in episodic recollection, and more similar neural representations across individuals. Together, these results suggest that when humans encode and retrieve complex real-world experiences, the reliability and accessibility of memory representations is shaped by their location within a network of events.

Neural representations during sleep: From sensory processing to memory traces

2007 ◽  
Vol 87 (3) ◽  
pp. 416-440 ◽  
Author(s):  
Elizabeth Hennevin ◽  
Chloé Huetz ◽  
Jean-Marc Edeline
Keyword(s):  
Sensory Processing ◽  
Neural Representations ◽  
Memory Traces

scholarly journals Suppression weakens unwanted memories via a sustained reduction of neural reactivation

2021 ◽  
Author(s):  
Ann-Kristin Meyer ◽  
Roland G. Benoit
Keyword(s):  
Intrusive Memories ◽  
Neural Representations ◽  
Parahippocampal Cortex ◽  
Aversive Events ◽  
Fmri Study ◽  
Sustained Reduction ◽  
Memory Representations ◽  
Scene Information ◽  
The Right ◽  
Study Participants

Aversive events often turn into intrusive memories. However, prior evidence indicates that these memories can be forgotten via a mechanism of retrieval suppression. Here, we test the hypothesis that suppression weakens memories by deteriorating their neural representations. This deterioration, in turn, would hinder their subsequent reactivation and thus impoverish the vividness with which they can be recalled. In an fMRI study, participants repeatedly suppressed memories of aversive scenes. As predicted, this process rendered the memories less vivid. Using a pattern classifier, we observed that it did diminish the reactivation of scene information both globally across the grey matter and locally in the parahippocampal cortices. Moreover, in the right parahippocampal cortex, a stronger decline in vividness was associated with a greater reduction in generic reactivation of scene information and in the specific reinstatement of unique memory representations. These results support the hypothesis that suppression deteriorates memories by compromising their neural representations.

scholarly journals Lateralized alpha oscillations are irrelevant for the behavioral retro-cueing benefit in visual working memory

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9398
Author(s):  
Wanja A. Mössing ◽  
Niko A. Busch
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Alpha Power ◽  
Behavioral Performance ◽  
Alpha Band ◽  
Limited Capacity ◽  
Irrelevant Distractors ◽  
Memory Representations ◽  
Precise Role

The limited capacity of visual working memory (vWM) necessitates the efficient allocation of available resources by prioritizing relevant over irrelevant items. Retro-cues, which inform about the future relevance of items after encoding has already finished, can improve the quality of memory representations of the relevant items. A candidate mechanism of this retro-cueing benefit is lateralization of neural oscillations in the alpha-band, but its precise role is still debated. The relative decrease of alpha power contralateral to the relevant items has been interpreted as supporting inhibition of irrelevant distractors or as supporting maintenance of relevant items. Here, we aimed at resolving this debate by testing how the magnitude of alpha-band lateralization affects behavioral performance: does stronger lateralization improve the precision of the relevant memory or does it reduce the biasing influence of the irrelevant distractor? We found that it does neither: while the data showed a clear retro-cue benefit and a biasing influence of non-target items as well as clear cue-induced alpha-band lateralization, the magnitude of this lateralization was not correlated with any performance parameter. This finding may indicate that alpha-band lateralization, which is typically observed in response to mnemonic cues, indicates an automatic shift of attention that only coincides with, but is not directly involved in mnemonic prioritization.

Drifting assemblies for persistent memory: Neuron transitions and unsupervised compensation

2021 ◽  
Vol 118 (46) ◽  
pp. e2023832118
Author(s):  
Yaroslav Felipe Kalle Kossio ◽  
Sven Goedeke ◽  
Christian Klos ◽  
Raoul-Martin Memmesheimer
Keyword(s):  
Temporal Evolution ◽  
Memory Systems ◽  
Homeostatic Plasticity ◽  
Network Activity ◽  
Associative Memories ◽  
Neural Representations ◽  
Persistent Memory ◽  
Memory Representations ◽  
Autonomous Network ◽  
Activity Dependent

Change is ubiquitous in living beings. In particular, the connectome and neural representations can change. Nevertheless, behaviors and memories often persist over long times. In a standard model, associative memories are represented by assemblies of strongly interconnected neurons. For faithful storage these assemblies are assumed to consist of the same neurons over time. Here we propose a contrasting memory model with complete temporal remodeling of assemblies, based on experimentally observed changes of synapses and neural representations. The assemblies drift freely as noisy autonomous network activity and spontaneous synaptic turnover induce neuron exchange. The gradual exchange allows activity-dependent and homeostatic plasticity to conserve the representational structure and keep inputs, outputs, and assemblies consistent. This leads to persistent memory. Our findings explain recent experimental results on temporal evolution of fear memory representations and suggest that memory systems need to be understood in their completeness as individual parts may constantly change.

scholarly journals Drifting Assemblies for Persistent Memory

2020 ◽  
Author(s):  
Yaroslav Felipe Kalle Kossio ◽  
Sven Goedeke ◽  
Christian Klos ◽  
Raoul-Martin Memmesheimer
Keyword(s):  
Temporal Evolution ◽  
Fear Memory ◽  
Memory Systems ◽  
Homeostatic Plasticity ◽  
Memory Model ◽  
Neural Representations ◽  
Random Activity ◽  
Persistent Memory ◽  
Memory Representations ◽  
Activity Dependent

Change is ubiquitous in living beings. In particular, the connectome and neural representations can change. Nevertheless behaviors and memories often persist over long times. In a standard model, memories are represented by assemblies of strongly interconnected neurons. For faithful storage these assemblies are assumed to consist of the same neurons over time. Here we propose a contrasting memory model with complete temporal remodeling of assemblies, based on experimentally observed changes of connections and neural representations. The assemblies drift freely as spontaneous synaptic turnover or random activity induce neuron exchange. The gradual exchange allows activity dependent and homeostatic plasticity to conserve the representational structure and keep inputs, outputs and assemblies consistent. This leads to persistent memory. Our findings explain recent experimental results on the temporal evolution of fear memory representations and suggest that memory systems need to be understood in their completeness as individual parts may constantly change.

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