Current Search:  Short-term memory (x)

View All Items

  • CSV Spreadsheet
(1 - 5 of 5)
THE STRUCTURAL ORGANIZATION AND SPECTRAL CHARACTERISTICS OF VISUAL WORKING MEMORY IN THE MONKEY FRONTOPARIETAL NETWORK
Title
THE STRUCTURAL ORGANIZATION AND SPECTRAL CHARACTERISTICS OF VISUAL WORKING MEMORY IN THE MONKEY FRONTOPARIETAL NETWORK.
Creator
Conklin, Bryan, Alexander, William, Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description
Working memory is a mental workspace which utilizes short and long-term memory to maintain and manipulate information. It is crucial in enabling cognitive control and is largely controlled by interactions within and between frontal and parietal cortices. Recent work has identified visual nonspatial, spatial, and visuospatial working memory spectral characteristics of the local field potential through simultaneous recordings from various areas across the monkey frontoparietal network. However,...
Show moreWorking memory is a mental workspace which utilizes short and long-term memory to maintain and manipulate information. It is crucial in enabling cognitive control and is largely controlled by interactions within and between frontal and parietal cortices. Recent work has identified visual nonspatial, spatial, and visuospatial working memory spectral characteristics of the local field potential through simultaneous recordings from various areas across the monkey frontoparietal network. However, the reports are minimal in number, and there is no clear narrative tying together the heterogenous functionality of the characteristics. Here, a new spectral model of monkey visual working memory is proposed to address these shortcomings. It highlights functional roles for low, mid, and high frequency bands. Next, the organization of structural connectivity which gives rise to these spectral characteristics is investigated. A new binary association matrix representing connections in the frontoparietal network is proposed. A graph theoretic analysis on the matrix found that a 3-node dynamical relaying M9 motif was a fundamental building block of the network. It is optimally structured for the synchrony found in the spectral model. The network was also found to have a small-world architecture, which confers the integration and specialization of function required by visual working memory. Afterwards, three hypotheses generated by the spectral model are tested on non-spatial data. The low and mid band hypotheses were supported by evidence, while the high band hypothesized activity was not observed. This adds credibility to the roles identified in the model for the low and mid band and identifies a need for further investigation of the high band role. Finally, opportunities to expand the spectral model, analyze the M9 motif, and further test the model are explored. In the future, the spectral model could evolve to apply its predictions to humans in the pursuit of treatments for neurological disorders.
Show less
Date Issued
2020
PURL
http://purl.flvc.org/fau/fd/FA00013584
Subject Headings
Memory, Short-Term, Working memory, Monkeys, Graph theory
Format
Document (PDF)
Mechanisms of Selective Attention in Working Memory, Modeled from Human Alpha Band Oscillations
Title
Mechanisms of Selective Attention in Working Memory, Modeled from Human Alpha Band Oscillations.
Creator
Nouri, Asal, Ester, Edward, Hahn, William, Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description
Working memory (WM) enables the flexible representation of information over short intervals. It is established that WM performance can be enhanced by a retrospective cue presented during storage, yet the neural mechanisms responsible for this benefit are unclear. Here, we tested several explanations for retrospective cue benefits by quantifying changes in spatial WM representations reconstructed from alpha-band (8 - 12 Hz) EEG activity recorded from human participants before and after the...
Show moreWorking memory (WM) enables the flexible representation of information over short intervals. It is established that WM performance can be enhanced by a retrospective cue presented during storage, yet the neural mechanisms responsible for this benefit are unclear. Here, we tested several explanations for retrospective cue benefits by quantifying changes in spatial WM representations reconstructed from alpha-band (8 - 12 Hz) EEG activity recorded from human participants before and after the presentation of a retrospective cue. This allowed us to track cue-related changes in WM representations with high temporal resolution. Our findings suggest that retrospective cues engage several different mechanisms such as recovery of information previously decreased to baseline after being cued as relevant and protecting the cued item from temporal decay to mitigate information loss during WM storage. Our EEG findings suggest that participants can supplement active memory traces with information from other memory stores. We next sought to better understand these additional store(s) by asking whether they are subject to the same temporal degradation seen in active memory representations during storage. We observed a significant increase in the quality of location representations following a retrocue, but the magnitude of this benefit was linearly and inversely related to the timing of the retrocue such that later cues yielded smaller increases.
Show less
Date Issued
2023
PURL
http://purl.flvc.org/fau/fd/FA00014192
Subject Headings
Working memory, Short-term memory, Attention, Alpha Rhythm
Format
Document (PDF)
Flexible Attentional Prioritization of Working Memory Object Representations
Title
Flexible Attentional Prioritization of Working Memory Object Representations.
Creator
Pytel, Paige, Ester, Edward, Florida Atlantic University, Department of Psychology, Charles E. Schmidt College of Science
Abstract/Description
Working memory (WM) is an important cognitive function that, among other duties, allows temporary storage of visual representations of objects observed in the sensorium. The visual aspect of this core cognitive function enables our perception of the identity of objects and where those objects are located in space at any particular time to help direct attention. In a typical working memory task, a cue is presented beforehand to guide attention to which objects in an array to encode. The...
Show moreWorking memory (WM) is an important cognitive function that, among other duties, allows temporary storage of visual representations of objects observed in the sensorium. The visual aspect of this core cognitive function enables our perception of the identity of objects and where those objects are located in space at any particular time to help direct attention. In a typical working memory task, a cue is presented beforehand to guide attention to which objects in an array to encode. The performance of our WM abilities can be improved on memory tasks by a retrospective cue resented after the encoding process of working memory. Several mechanisms have been proposed to explain etrospective cue benefits in WM performance, including the removal of irrelevant information from WM, attentional enhancement of the cued representation, protection of the cued representation from subsequent decay or interference, or retrieval head start.
Show less
Date Issued
2019
PURL
http://purl.flvc.org/fau/fd/FA00013406
Subject Headings
Memory, Short-Term, Cues, Visual perception, Electroencephalography
Format
Document (PDF)
EEG SIGNALS REPRESENT UPDATED MEMORY REPRESENTATIONS IN VISUAL WORKING MEMORY
Title
EEG SIGNALS REPRESENT UPDATED MEMORY REPRESENTATIONS IN VISUAL WORKING MEMORY.
Creator
Shin, Young Seon, Sheremata, Summer L., Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description
Visual working memory (VWM) is a core cognitive system that supports our ability to maintain and manipulate visual information temporarily when sensory information is no longer present in the environment. VWM and mental rotation, a form of mental imagery, require the ability to generate internal images in the absence of stimuli. Both cognitive processes share visual buffer and are associated with representing and manipulating visual information, however, little is known about the intersection...
Show moreVisual working memory (VWM) is a core cognitive system that supports our ability to maintain and manipulate visual information temporarily when sensory information is no longer present in the environment. VWM and mental rotation, a form of mental imagery, require the ability to generate internal images in the absence of stimuli. Both cognitive processes share visual buffer and are associated with representing and manipulating visual information, however, little is known about the intersection between VWM and mental rotation. In the current work, mental rotation was adopted to study updated mnemonic contents in VWM. In this dissertation, I asked whether the brain mechanisms that support VWM and mental rotation overlap. Participants were asked to remember the orientation of grating or to remember and manipulate, that is mentally rotate, the orientation of grating. Behavioral results showed that mental rotation induced lower fidelity representations of orientation. This confirmed that additional usage in visual buffer to manipulate the visual representation provoked by mental rotation involved negative influence in memory fidelity. In the second study, EEG recording was conducted while participants performed the same task. Visual representations were reconstructed from brain oscillations using the inverted encoding model (IEM). It was found that orientation information from the reconstruction was represented in the amplitude of alpha oscillations (8 – 12 Hz) for both maintained and updated mnemonic contents. Together, this work provides evidence that memory manipulation driven by mental rotation has a decisive effect on the fidelity of visual representations in VWM. Additionally this dissertation demonstrates that the updated memory representations as well as the maintained memory representations are carried in EEG oscillations.
Show less
Date Issued
2022
PURL
http://purl.flvc.org/fau/fd/FA00013890
Subject Headings
Short-term memory, Visual Perception, Electroencephalography, Mental rotation
Format
Document (PDF)
Time-frequency classification of gamma oscillatory activity in the frontoparietal system during working memory
Title
Time-frequency classification of gamma oscillatory activity in the frontoparietal system during working memory.
Creator
Romano, Tracy A., Bressler, Steven L., Florida Atlantic University, Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description
Working memory (WM) is a process that allows for the temporary and limited storage of information for an immediate goal or to be stored into a more permanent system. A large number of studies have led to the widely accepted view that WM is mediated by the frontoparietal network (FPN), consisting of areas in the prefrontal cortex (PFC) and posterior parietal cortex (PPC). Current evidence suggests that task specific patterns of neuronal oscillatory activity within the FPN play a fundamental...
Show moreWorking memory (WM) is a process that allows for the temporary and limited storage of information for an immediate goal or to be stored into a more permanent system. A large number of studies have led to the widely accepted view that WM is mediated by the frontoparietal network (FPN), consisting of areas in the prefrontal cortex (PFC) and posterior parietal cortex (PPC). Current evidence suggests that task specific patterns of neuronal oscillatory activity within the FPN play a fundamental role in WM, and yet specific spatio-temporal properties of this activity are not well characterized. This study utilized multisite local field potential (LFP) data recorded from PFC and PPC sites in two macaque monkeys trained to perform a rule-based, Oculomotor Delayed Match-to-Sample task. The animals were required to learn which of two rules determined the correct match (Location matching or Identity matching). Following a 500 ms fixation period, a sample stimulus was presented for 500 ms, followed by a randomized delay lasting 800-1200 ms in which no stimulus was present. At the end of the delay period, a match stimulus was presented, consisting of two of three possible objects presented at two of three possible locations. When the match stimulus appeared, the monkey made a saccadic eye movement to the target. The rule in effect determined which object served as the target. Time-frequency plots of three spectral measures (power, coherence, and Wiener Granger Causality (WGC) were computed from MultiVariate AutoRegressive LFP time-series models estimated in a 100-ms window that was slid across each of three analysis epochs (fixation, sample, and delay). Low (25- 55 Hz) and high gamma (65- 100 Hz) activity were investigated separately due to evidence that they may be functionally distinct. Within each epoch, recording sites in the PPC and PFC were classified into groups according to the similarity of their power t-f plots derived by a K-means clustering algorithm. From the power-based site groups, the corresponding coherence and WGC were analyzed. This classification procedure uncovered spatial, temporal, and frequency dynamics of FPN involvement in WM and other co-occurring processes, such as sensory and target related processes. These processes were distinguishable by rule and performance accuracy across all three spectral measures- power, coherence, and WGC. Location and Identity rule were distinguishable by the low and high-gamma range.
Show less
Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00004157
Subject Headings
Brain--Physiology., Biological rhythms., Attention--Physiological aspects., Cognitive neuroscience., Memory--Age factors., Short-term memory., Neural networks (Computer science)
Format
Document (PDF)