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A recurrent neural network model of prefrontal brain activity during a working memory task

When multiple items are held in short-term memory, cues that retrospectively prioritise one item over another (retro-cues) can facilitate subsequent recall. However, the neural and computational underpinnings of this effect are poorly understood. One recent study recorded neural signals in the macaq...

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Detalles Bibliográficos
Autores principales: Piwek, Emilia P., Stokes, Mark G., Summerfield, Christopher
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10615291/
https://www.ncbi.nlm.nih.gov/pubmed/37851670
http://dx.doi.org/10.1371/journal.pcbi.1011555
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author Piwek, Emilia P.
Stokes, Mark G.
Summerfield, Christopher
author_facet Piwek, Emilia P.
Stokes, Mark G.
Summerfield, Christopher
author_sort Piwek, Emilia P.
collection PubMed
description When multiple items are held in short-term memory, cues that retrospectively prioritise one item over another (retro-cues) can facilitate subsequent recall. However, the neural and computational underpinnings of this effect are poorly understood. One recent study recorded neural signals in the macaque lateral prefrontal cortex (LPFC) during a retro-cueing task, contrasting delay-period activity before (pre-cue) and after (post-cue) retrocue onset. They reported that in the pre-cue delay, the individual stimuli were maintained in independent subspaces of neural population activity, whereas in the post-cue delay, the prioritised items were rotated into a common subspace, potentially allowing a common readout mechanism. To understand how such representational transitions can be learnt through error minimisation, we trained recurrent neural networks (RNNs) with supervision to perform an equivalent cued-recall task. RNNs were presented with two inputs denoting conjunctive colour-location stimuli, followed by a pre-cue memory delay, a location retrocue, and a post-cue delay. We found that the orthogonal-to-parallel geometry transformation observed in the macaque LPFC emerged naturally in RNNs trained to perform the task. Interestingly, the parallel geometry only developed when the cued information was required to be maintained in short-term memory for several cycles before readout, suggesting that it might confer robustness during maintenance. We extend these findings by analysing the learning dynamics and connectivity patterns of the RNNs, as well as the behaviour of models trained with probabilistic cues, allowing us to make predictions for future studies. Overall, our findings are consistent with recent theoretical accounts which propose that retrocues transform the prioritised memory items into a prospective, action-oriented format.
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spelling pubmed-106152912023-10-31 A recurrent neural network model of prefrontal brain activity during a working memory task Piwek, Emilia P. Stokes, Mark G. Summerfield, Christopher PLoS Comput Biol Research Article When multiple items are held in short-term memory, cues that retrospectively prioritise one item over another (retro-cues) can facilitate subsequent recall. However, the neural and computational underpinnings of this effect are poorly understood. One recent study recorded neural signals in the macaque lateral prefrontal cortex (LPFC) during a retro-cueing task, contrasting delay-period activity before (pre-cue) and after (post-cue) retrocue onset. They reported that in the pre-cue delay, the individual stimuli were maintained in independent subspaces of neural population activity, whereas in the post-cue delay, the prioritised items were rotated into a common subspace, potentially allowing a common readout mechanism. To understand how such representational transitions can be learnt through error minimisation, we trained recurrent neural networks (RNNs) with supervision to perform an equivalent cued-recall task. RNNs were presented with two inputs denoting conjunctive colour-location stimuli, followed by a pre-cue memory delay, a location retrocue, and a post-cue delay. We found that the orthogonal-to-parallel geometry transformation observed in the macaque LPFC emerged naturally in RNNs trained to perform the task. Interestingly, the parallel geometry only developed when the cued information was required to be maintained in short-term memory for several cycles before readout, suggesting that it might confer robustness during maintenance. We extend these findings by analysing the learning dynamics and connectivity patterns of the RNNs, as well as the behaviour of models trained with probabilistic cues, allowing us to make predictions for future studies. Overall, our findings are consistent with recent theoretical accounts which propose that retrocues transform the prioritised memory items into a prospective, action-oriented format. Public Library of Science 2023-10-18 /pmc/articles/PMC10615291/ /pubmed/37851670 http://dx.doi.org/10.1371/journal.pcbi.1011555 Text en © 2023 Piwek et al https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Piwek, Emilia P.
Stokes, Mark G.
Summerfield, Christopher
A recurrent neural network model of prefrontal brain activity during a working memory task
title A recurrent neural network model of prefrontal brain activity during a working memory task
title_full A recurrent neural network model of prefrontal brain activity during a working memory task
title_fullStr A recurrent neural network model of prefrontal brain activity during a working memory task
title_full_unstemmed A recurrent neural network model of prefrontal brain activity during a working memory task
title_short A recurrent neural network model of prefrontal brain activity during a working memory task
title_sort recurrent neural network model of prefrontal brain activity during a working memory task
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10615291/
https://www.ncbi.nlm.nih.gov/pubmed/37851670
http://dx.doi.org/10.1371/journal.pcbi.1011555
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