Coding with transient trajectories in recurrent neural networks.

Following a stimulus, the neural response typically strongly varies in time and across neurons before settling to a steady-state. While classical population coding theory disregards the temporal dimension, recent works have argued that trajectories of transient activity can be particularly informati...

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Main Authors: Giulio Bondanelli, Srdjan Ostojic
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2020-02-01
Series:PLoS Computational Biology
Online Access:https://doi.org/10.1371/journal.pcbi.1007655
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author Giulio Bondanelli
Srdjan Ostojic
author_facet Giulio Bondanelli
Srdjan Ostojic
author_sort Giulio Bondanelli
collection DOAJ
description Following a stimulus, the neural response typically strongly varies in time and across neurons before settling to a steady-state. While classical population coding theory disregards the temporal dimension, recent works have argued that trajectories of transient activity can be particularly informative about stimulus identity and may form the basis of computations through dynamics. Yet the dynamical mechanisms needed to generate a population code based on transient trajectories have not been fully elucidated. Here we examine transient coding in a broad class of high-dimensional linear networks of recurrently connected units. We start by reviewing a well-known result that leads to a distinction between two classes of networks: networks in which all inputs lead to weak, decaying transients, and networks in which specific inputs elicit amplified transient responses and are mapped onto output states during the dynamics. Theses two classes are simply distinguished based on the spectrum of the symmetric part of the connectivity matrix. For the second class of networks, which is a sub-class of non-normal networks, we provide a procedure to identify transiently amplified inputs and the corresponding readouts. We first apply these results to standard randomly-connected and two-population networks. We then build minimal, low-rank networks that robustly implement trajectories mapping a specific input onto a specific orthogonal output state. Finally, we demonstrate that the capacity of the obtained networks increases proportionally with their size.
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spelling doaj.art-d1b81ade38b7424c9335bf3a45ed58792022-12-21T21:27:32ZengPublic Library of Science (PLoS)PLoS Computational Biology1553-734X1553-73582020-02-01162e100765510.1371/journal.pcbi.1007655Coding with transient trajectories in recurrent neural networks.Giulio BondanelliSrdjan OstojicFollowing a stimulus, the neural response typically strongly varies in time and across neurons before settling to a steady-state. While classical population coding theory disregards the temporal dimension, recent works have argued that trajectories of transient activity can be particularly informative about stimulus identity and may form the basis of computations through dynamics. Yet the dynamical mechanisms needed to generate a population code based on transient trajectories have not been fully elucidated. Here we examine transient coding in a broad class of high-dimensional linear networks of recurrently connected units. We start by reviewing a well-known result that leads to a distinction between two classes of networks: networks in which all inputs lead to weak, decaying transients, and networks in which specific inputs elicit amplified transient responses and are mapped onto output states during the dynamics. Theses two classes are simply distinguished based on the spectrum of the symmetric part of the connectivity matrix. For the second class of networks, which is a sub-class of non-normal networks, we provide a procedure to identify transiently amplified inputs and the corresponding readouts. We first apply these results to standard randomly-connected and two-population networks. We then build minimal, low-rank networks that robustly implement trajectories mapping a specific input onto a specific orthogonal output state. Finally, we demonstrate that the capacity of the obtained networks increases proportionally with their size.https://doi.org/10.1371/journal.pcbi.1007655
spellingShingle Giulio Bondanelli
Srdjan Ostojic
Coding with transient trajectories in recurrent neural networks.
PLoS Computational Biology
title Coding with transient trajectories in recurrent neural networks.
title_full Coding with transient trajectories in recurrent neural networks.
title_fullStr Coding with transient trajectories in recurrent neural networks.
title_full_unstemmed Coding with transient trajectories in recurrent neural networks.
title_short Coding with transient trajectories in recurrent neural networks.
title_sort coding with transient trajectories in recurrent neural networks
url https://doi.org/10.1371/journal.pcbi.1007655
work_keys_str_mv AT giuliobondanelli codingwithtransienttrajectoriesinrecurrentneuralnetworks
AT srdjanostojic codingwithtransienttrajectoriesinrecurrentneuralnetworks