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Dopamine-modulated dynamic cell assemblies generated by the GABAergic striatal microcircuit

Humphries, M.D., Wood, R. and Gurney, K. (2009) Dopamine-modulated dynamic cell assemblies generated by the GABAergic striatal microcircuit. Neural Networks, 22 (8). pp. 1174-1188. ISSN 0893-6080

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Abstract

The striatum, the principal input structure of the basal ganglia, is crucial to both motor control and learning. It receives convergent input from all over the neocortex, hippocampal formation, amygdala and thalamus, and is the primary recipient of dopamine in the brain. Within the striatum is a GABAergic microcircuit that acts upon these inputs, formed by the dominant medium-spiny projection neurons (MSNs) and fast-spiking interneurons (FSIs). There has been little progress in understanding the computations it performs, hampered by the non-laminar structure that prevents identification of a repeating canonical microcircuit. We here begin the identification of potential dynamically-defined computational elements within the striatum. We construct a new three-dimensional model of the striatal microcircuit's connectivity, and instantiate this with our dopamine-modulated neuron models of the MSNs and FSIs. A new model of gap junctions between the FSIs is introduced and tuned to experimental data. We introduce a novel multiple spike-train analysis method, and apply this to the outputs of the model to find groups of synchronised neurons at multiple time-scales. We find that, with realistic in vivo background input, small assemblies of synchronised MSNs spontaneously appear, consistent with experimental observations, and that the number of assemblies and the time-scale of synchronisation is strongly dependent on the simulated concentration of dopamine. We also show that feed-forward inhibition from the FSIs counter-intuitively increases the firing rate of the MSNs. Such small cell assemblies forming spontaneously only in the absence of dopamine may contribute to motor control problems seen in humans and animals following a loss of dopamine cells. (C) 2009 Elsevier Ltd. All rights reserved.

Item Type: Article
Copyright, Publisher and Additional Information: © 2009 Elsevier. This is an author produced version of a paper subsequently published in Neural Networks. Uploaded in accordance with the publisher's self-archiving policy.
Keywords: Striatum; Parkinson's disease; Action selection; Large-scale models; Izhikevich neuron model
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > Department of Psychology (Sheffield)
Depositing User: Miss Anthea Tucker
Date Deposited: 10 Nov 2009 11:10
Last Modified: 08 Feb 2013 16:59
Published Version: http://dx.doi.org/10.1016/j.neunet.2009.07.018
Status: Published
Publisher: Elsevier
Refereed: Yes
Identification Number: 10.1016/j.neunet.2009.07.018
URI: http://eprints.whiterose.ac.uk/id/eprint/10120

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