scholarly journals Fronto-medial theta coordinates posterior maintenance of working memory content

2021 ◽  
Author(s):  
Oliver Ratcliffe ◽  
Kimron Shapiro ◽  
Bernhard P. Staresina
Keyword(s):  
Working Memory ◽  
Computational Models ◽  
Medial Cortex ◽  
Duty Cycles ◽  
Machine Learning Approach ◽  
Theta Frequency ◽  
Oscillatory Power ◽  
Posterior Parietal ◽  
Memory Content ◽  
Memory Contents

AbstractHow does the human brain manage multiple bits of information to guide goal-directed behaviour? Successful working memory (WM) functioning has consistently been linked to oscillatory power in the theta frequency band (4-8 Hz) over fronto-medial cortex (fronto-medial theta, FMT). Specifically, FMT is thought to reflect the mechanism of an executive sub-system that coordinates maintenance of memory contents in posterior regions. However, direct evidence for the role of FMT in controlling specific WM content is lacking. Here we collected high-density Electroencephalography (EEG) data whilst participants engaged in load-varying WM tasks and then used multivariate decoding methods to examine WM content during the maintenance period. Higher WM load elicited a focal increase in FMT. Importantly, decoding of WM content was driven by posterior/parietal sites, which in turn showed load-induced functional theta coupling with fronto-medial cortex. Finally, we observed a significant slowing of FMT frequency with increasing WM load, consistent with the hypothesised broadening of a theta ‘duty cycle’ to accommodate additional WM items. Together these findings demonstrate that frontal theta orchestrates posterior maintenance of WM content. Moreover, the observed frequency slowing elucidates the function of FMT oscillations by specifically supporting phase-coding accounts of WM.Significance StatementHow does the brain juggle the maintenance of multiple items in working memory (WM)? Here we show that increased WM demands increase theta power (4-8 Hz) in fronto-medial cortex. Interestingly, using a machine learning approach, we found that the content held in WM could be read out not from frontal, but from posterior areas. These areas were in turn functionally coupled with fronto-medial cortex, consistent with the idea that frontal cortex orchestrates WM representations in posterior regions. Finally, we observed that holding an additional item in WM leads to significant slowing of the frontal theta rhythm, supporting computational models that postulate longer ‘duty cycles’ to accommodate additional WM demands.

scholarly journals Working memory and decision making in a fronto-parietal circuit model

2017 ◽  
Author(s):  
John D. Murray ◽  
Jorge Jaramillo ◽  
Xiao-Jing Wang
Keyword(s):  
Decision Making ◽  
Working Memory ◽  
Cognitive Function ◽  
Computational Models ◽  
Target Selection ◽  
Circuit Model ◽  
Hierarchical Processing ◽  
Posterior Parietal ◽  
Cognitive Computation ◽  
Parsimonious Model

AbstractWorking memory (WM) and decision making (DM) are fundamental cognitive functions involving a distributed interacting network of brain areas, with the posterior parietal and prefrontal cortices (PPC and PFC) at the core. However, the shared and distinct roles of these areas and the nature of their coordination in cognitive function remain poorly understood. Biophysically-based computational models of cortical circuits have provided insights into the mechanisms supporting these functions, yet they have primarily focused on the local microcircuit level, raising questions about the principles for distributed cognitive computation in multi-regional networks. To examine these issues, we developed a distributed circuit model of two reciprocally interacting modules representing PPC and PFC circuits. The circuit architecture includes hierarchical differences in local recurrent structure and implements reciprocal long-range projections. This parsimonious model captures a range of behavioral and neuronal features of fronto-parietal circuits across multiple WM and DM paradigms. In the context of WM, both areas exhibit persistent activity, but in response to intervening distractors, PPC transiently encodes distractors, while PFC filters distractors and supports WM robustness. With regards to DM, the PPC module generates graded representations of accumulated evidence supporting target selection, while the PFC module generates more categorical responses related to action or choice. These findings suggest computational principles for distributed, hierarchical processing in cortex during cognitive function, and provide a framework for extension to multi-regional models.

scholarly journals Hemispheric asymmetries in posterior alpha power reflect the selection and inhibition of spatial context information in working memory

2019 ◽  
Author(s):  
Marlene Roesner ◽  
Stefan Arnau ◽  
Isabel Skiba ◽  
Edmund Wascher ◽  
Daniel Schneider
Keyword(s):  
Working Memory ◽  
Memory Task ◽  
Relevant Information ◽  
Spatial Context ◽  
Alpha Power ◽  
Hemispheric Asymmetries ◽  
Distractor Processing ◽  
Oscillatory Power ◽  
Memory Content ◽  
The Impact

There is an ongoing debate on the contribution of target enhancement and distractor inhibition processes to selective attention. In a working memory task, we presented to-be-memorized information in a way that posterior hemispheric asymmetries in oscillatory power could be unambiguously linked to lateral target vs. distractor processing. Alpha power asymmetries (8-14 Hz) were insensitive to the number of cued or non-cued items, supporting their relation to spatial attention. Furthermore, we found an increase in alpha power contralateral to non-cued working memory content and an alpha power suppression contralateral to relevant information. These oscillatory patterns relative to the positions of cued and non-cued items were related to the participants' ability to control for the impact of irrelevant information on working memory retrieval. Based on these results, we propose that spatially specific modulations of posterior alpha power are related to accessing vs. inhibiting the spatial context of information stored in working memory.

scholarly journals Temporal Properties of Posterior Parietal Neuron Discharges During Working Memory and Passive Viewing

2007 ◽  
Vol 97 (3) ◽  
pp. 2254-2266 ◽  
Author(s):  
Frederik C. Joelving ◽  
Albert Compte ◽  
Christos Constantinidis
Keyword(s):  
Working Memory ◽  
Posterior Parietal Cortex ◽  
Memory Task ◽  
Power Spectra ◽  
Low Frequency ◽  
Spatial Location ◽  
Spike Trains ◽  
Memory Condition ◽  
Temporal Properties ◽  
Posterior Parietal

Working memory is mediated by the discharges of neurons in a distributed network of brain areas. It was recently suggested that enhanced rhythmicity in neuronal activity may be critical for sustaining remembered information. To test whether working memory is characterized by unique temporal discharge patterns, we analyzed the autocorrelograms and power spectra of spike trains recorded from the posterior parietal cortex of monkeys performing a visuospatial working-memory task. We compared the intervals of active memory maintenance and fixation and repeated the same analysis in spike trains from monkeys never trained to perform any kind of memory task. The most salient effect we observed was a decrease of power in the 5- to 10-Hz frequency range during the presentation of visual stimuli. This pattern was observed both in the working-memory condition and the control condition, although it was more prominent in the former, where it persisted after cue presentation when the monkeys actively remembered the spatial location of the stimulus. Low-frequency power suppression resulted from relative refractory periods that were significantly longer in the working-memory condition and presumably emerged from local-circuit inhibition. We also detected a spectral peak in the 15- to 20-Hz range, although this was more prominent during fixation than during the stimulus and working-memory periods. Our results are in line with previous reports in prefrontal cortex and indicate that unique temporal patterns of single-neuron firing characterize persistent delay activity, although these do not involve the appearance of enhanced oscillations.

scholarly journals Atypically larger variability of resource allocation accounts for visual working memory deficits in schizophrenia

2018 ◽  
Author(s):  
Yi-Jie Zhao ◽  
Tianye Ma ◽  
Xuemei Ran ◽  
Li Zhang ◽  
Ru-Yuan Zhang ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Computational Models ◽  
Variable Precision ◽  
Capacity Theory ◽  
Healthy Control ◽  
New Perspective ◽  
Almost All ◽  
Memory Precision ◽  
Memory Resources

AbstractSchizophrenia patients are known to have profound deficits in visual working memory (VWM), and almost all previous studies attribute the deficits to decreased memory capacity. This account, however, ignores the potential contributions of other VWM components (e.g., memory precision). Here, we measure the VWM performance of schizophrenia patients and healthy control subjects on two classical delay-estimation tasks. Moreover, we thoroughly evaluate several established computational models of VWM to compare the performance of the two groups. We find that the model assuming variable precision across items and trials is the best model to explain the performance of both groups. According to the variable-precision model, schizophrenia subjects exhibit abnormally larger variability of allocating memory resources rather than resources per se. These results invite a rethink of the widely accepted decreased-capacity theory and propose a new perspective on the diagnosis and rehabilitation of schizophrenia.

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