Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Restoring Latent Visual Working Memory Representations in Human Cortex.

ABSTRACT: Working memory (WM) enables the storage and manipulation of limited amounts of information over short periods. Prominent models posit that increasing the number of remembered items decreases the spiking activity dedicated to each item via mutual inhibition, which irreparably degrades the fidelity of each item's representation. We tested these models by determining if degraded memory representations could be recovered following a post-cue indicating which of several items in spatial WM would be recalled. Using an fMRI-based image reconstruction technique, we identified impaired behavioral performance and degraded mnemonic representations with elevated memory load. However, in several cortical regions, degraded mnemonic representations recovered substantially following a post-cue, and this recovery tracked behavioral performance. These results challenge pure spike-based models of WM and suggest that remembered items are additionally encoded within latent or hidden neural codes that can help reinvigorate active WM representations.

SUBMITTER: Sprague TC

PROVIDER: S-EPMC4978188 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Restoring Latent Visual Working Memory Representations in Human Cortex.

Sprague Thomas C TC Ester Edward F EF Serences John T JT

Neuron 20160801 3

Working memory (WM) enables the storage and manipulation of limited amounts of information over short periods. Prominent models posit that increasing the number of remembered items decreases the spiking activity dedicated to each item via mutual inhibition, which irreparably degrades the fidelity of each item's representation. We tested these models by determining if degraded memory representations could be recovered following a post-cue indicating which of several items in spatial WM would be r ...[more]

PMID: 27497224

Similar Datasets

Spatially global representations in human primary visual cortex during working memory maintenance.

Project description:Recent studies suggest that visual features are stored in working memory (WM) via sensory recruitment or sustained stimulus-specific patterns of activity in cortical regions that encode memoranda. One important question concerns the spatial extent of sensory recruitment. One possibility is that sensory recruitment is restricted to neurons that are retinotopically mapped to the positions occupied by the remembered items. Alternatively, specific feature values could be represented via a spatially global recruitment of neurons that encode the remembered feature, regardless of the retinotopic position of the remembered stimulus. Here, we evaluated these alternatives by requiring subjects to remember the orientation of a grating presented in the left or right visual field. Functional magnetic resonance imaging and multivoxel pattern analysis were then used to examine feature-specific activations in early visual regions during memory maintenance. Activation patterns that discriminated the remembered feature were found in regions of contralateral visual cortex that corresponded to the retinotopic position of the remembered item, as well as in ipsilateral regions that were not retinotopically mapped to the position of the stored stimulus. These results suggest that visual details are held in WM through a spatially global recruitment of early sensory cortex. This spatially global recruitment may enhance memory precision by facilitating robust population coding of the stored information.

| S-EPMC2830793 | biostudies-literature

Working memory representations in visual cortex mediate distraction effects.

Project description:Although the contents of working memory can be decoded from visual cortex activity, these representations may play a limited role if they are not robust to distraction. We used model-based fMRI to estimate the impact of distracting visual tasks on working memory representations in several visual field maps in visual and frontoparietal association cortex. Here, we show distraction causes the fidelity of working memory representations to briefly dip when both the memorandum and distractor are jointly encoded by the population activities. Distraction induces small biases in memory errors which can be predicted by biases in neural decoding in early visual cortex, but not other regions. Although distraction briefly disrupts working memory representations, the widespread redundancy with which working memory information is encoded may protect against catastrophic loss. In early visual cortex, the neural representation of information in working memory and behavioral performance are intertwined, solidifying its importance in visual memory.

| S-EPMC8342709 | biostudies-literature

Interactions between visual working memory representations.

Project description:We investigated whether the representations of different objects are maintained independently in working memory or interact with each other. Observers were shown two sequentially presented orientations and required to reproduce each orientation after a delay. The sequential presentation minimized perceptual interactions so that we could isolate interactions between memory representations per se. We found that similar orientations were repelled from each other whereas dissimilar orientations were attracted to each other. In addition, when one of the items was given greater attentional priority by means of a cue, the representation of the high-priority item was not influenced very much by the orientation of the low-priority item, but the representation of the low-priority item was strongly influenced by the orientation of the high-priority item. This indicates that attention modulates the interactions between working memory representations. In addition, errors in the reported orientations of the two objects were positively correlated under some conditions, suggesting that representations of distinct objects may become grouped together in memory. Together, these results demonstrate that working-memory representations are not independent but instead interact with each other in a manner that depends on attentional priority.

| S-EPMC5744598 | biostudies-literature

Parietal and Frontal Cortex Encode Stimulus-Specific Mnemonic Representations during Visual Working Memory.

Project description:Working memory (WM) enables the storage and manipulation of information in an active state. WM storage has long been associated with sustained increases in activation across a network of frontal and parietal cortical regions. However, recent evidence suggests that these regions primarily encode information related to general task goals rather than feature-selective representations of specific memoranda. These goal-related representations are thought to provide top-down feedback that coordinates the representation of fine-grained details in early sensory areas. Here, we test this model using fMRI-based reconstructions of remembered visual details from region-level activation patterns. We could reconstruct high-fidelity representations of a remembered orientation based on activation patterns in occipital visual cortex and in several sub-regions of frontal and parietal cortex, independent of sustained increases in mean activation. These results challenge models of WM that postulate disjoint frontoparietal "top-down control" and posterior sensory "feature storage" networks.

| S-EPMC4545683 | biostudies-literature

Discrete fixed-resolution representations in visual working memory.

Project description:Limits on the storage capacity of working memory significantly affect cognitive abilities in a wide range of domains, but the nature of these capacity limits has been elusive. Some researchers have proposed that working memory stores a limited set of discrete, fixed-resolution representations, whereas others have proposed that working memory consists of a pool of resources that can be allocated flexibly to provide either a small number of high-resolution representations or a large number of low-resolution representations. Here we resolve this controversy by providing independent measures of capacity and resolution. We show that, when presented with more than a few simple objects, human observers store a high-resolution representation of a subset of the objects and retain no information about the others. Memory resolution varied over a narrow range that cannot be explained in terms of a general resource pool but can be well explained by a small set of discrete, fixed-resolution representations.

| S-EPMC2588137 | biostudies-literature

Ensemble representations reveal distinct neural coding of visual working memory.

Project description:We characterized the population-level neural coding of ensemble representations in visual working memory from human electroencephalography. Ensemble representations provide a unique opportunity to investigate structured representations of working memory because the visual system encodes high-order summary statistics as well as noisy sensory inputs in a hierarchical manner. Here, we consistently observe stable coding of simple features as well as the ensemble mean in frontocentral electrodes, which even correlated with behavioral indices of the ensemble across individuals. In occipitoparietal electrodes, however, we find that remembered features are dynamically coded over time, whereas neural coding of the ensemble mean is absent in the old/new judgment task. In contrast, both dynamic and stable coding are found in the continuous estimation task. Our findings suggest that the prefrontal cortex holds behaviorally relevant abstract representations while visual representations in posterior and visual areas are modulated by the task demands.

| S-EPMC6906315 | biostudies-literature

Alternating capture of attention by multiple visual working memory representations.

Project description:Can we look for multiple objects simultaneously? Previous studies have proposed that the representation of an item in visual working memory (VWM) can bias the deployment of attention to memory-matching items in visual search. However, it is still controversial whether multiple VWM item representations are able to capture attention. In the present study, we adopted an eye-tracking technique to reveal this issue. In Experiment 1, we replicated Chen and Du's Experiment 2 and adopted an eye-tracking technique to determine whether multiple VWM item representations are able to bias attention. In Chen and Du's paradigm, the memory test was always followed by the search test, and the participants might intentionally prepare for the search task, which can affect the results of the research. Thus, in Experiment 2, we prevented participants from predicting the temporal occurrence of the visual search task by randomly conducting a search test or a memory test after memoranda. The findings of the present study suggested that only one working memory item at a time influences attention and multiple working memory items may affect attention through alternation. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on September 5, 2022. The protocol, as accepted by the journal, can be found at: https://doi.org/10.17605/OSF.IO/BE529 .

| S-EPMC10415262 | biostudies-literature

Project description:A relatively new analysis technique, known as neural decoding or multivariate pattern analysis (MVPA), has become increasingly popular for cognitive neuroimaging studies over recent years. These techniques promise to uncover the representational contents of neural signals, as well as the underlying code and the dynamic profile thereof. A field in which these techniques have led to novel insights in particular is that of visual working memory (VWM). In the present study, we subjected human volunteers to a combined VWM/imagery task while recording their neural signals using magnetoencephalography (MEG). We applied multivariate decoding analyses to uncover the temporal profile underlying the neural representations of the memorized item. Analysis of gaze position however revealed that our results were contaminated by systematic eye movements, suggesting that the MEG decoding results from our originally planned analyses were confounded. In addition to the eye movement analyses, we also present the original analyses to highlight how these might have readily led to invalid conclusions. Finally, we demonstrate a potential remedy, whereby we train the decoders on a functional localizer that was specifically designed to target bottom-up sensory signals and as such avoids eye movements. We conclude by arguing for more awareness of the potentially pervasive and ubiquitous effects of eye movement-related confounds.

| S-EPMC6179574 | biostudies-literature

Prefrontal Lesions Disrupt Posterior Alpha-Gamma Coordination of Visual Working Memory Representations.

Project description:How does the human brain prioritize different visual representations in working memory (WM)? Here, we define the oscillatory mechanisms supporting selection of "where" and "when" features from visual WM storage and investigate the role of pFC in feature selection. Fourteen individuals with lateral pFC damage and 20 healthy controls performed a visuospatial WM task while EEG was recorded. On each trial, two shapes were presented sequentially in a top/bottom spatial orientation. A retro-cue presented mid-delay prompted which of the two shapes had been in either the top/bottom spatial position or first/second temporal position. We found that cross-frequency coupling between parieto-occipital alpha (α; 8-12 Hz) oscillations and topographically distributed gamma (γ; 30-50 Hz) activity tracked selection of the distinct cued feature in controls. This signature of feature selection was disrupted in patients with pFC lesions, despite intact α-γ coupling independent of feature selection. These findings reveal a pFC-dependent parieto-occipital α-γ mechanism for the rapid selection of visual WM representations.

| S-EPMC8428813 | biostudies-literature

Different states of priority recruit different neural representations in visual working memory.

Project description:We used functional magnetic resonance imaging (fMRI) to investigate the neural codes for representing stimulus information held in different states of priority in working memory. Human participants (male and female) performed delayed recall for 2 oriented gratings that could appear in any of several locations. Priority status was manipulated by a retrocue, such that one became the prioritized memory item (PMI) and another the unprioritized memory item (UMI). Using inverted encoding models (IEMs), we found that, in early visual cortex, the orientation of the UMI was represented in a neural representation that was rotated relative to the PMI. In intraparietal sulcus (IPS), we observed the analogous effect for the representation of the location of the UMI. Taken together, these results provide evidence for a common remapping mechanism that may be responsible for representing stimulus identity and stimulus context with different levels of priority in working memory.

| S-EPMC7351225 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data