Document Detail


Short-term plasticity explains irregular persistent activity in working memory tasks.
MedLine Citation:
PMID:  23283328     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Persistent activity in cortex is the neural correlate of working memory (WM). In persistent activity, spike trains are highly irregular, even more than in baseline. This seemingly innocuous feature challenges our current understanding of the synaptic mechanisms underlying WM. Here we argue that in WM the prefrontal cortex (PFC) operates in a regime of balanced excitation and inhibition and that the observed temporal irregularity reflects this regime. We show that this requires that nonlinearities underlying the persistent activity are primarily in the neuronal interactions between PFC neurons. We also show that short-term synaptic facilitation can be the physiological substrate of these nonlinearities and that the resulting mechanism of balanced persistent activity is robust, in particular with respect to changes in the connectivity. As an example, we put forward a computational model of the PFC circuit involved in oculomotor delayed response task. The novelty of this model is that recurrent excitatory synapses are facilitating. We demonstrate that this model displays direction-selective persistent activity. We find that, even though the memory eventually degrades because of the heterogeneities, it can be stored for several seconds for plausible network size and connectivity. This model accounts for a large number of experimental findings, such as the findings that have shown that firing is more irregular during the persistent state than during baseline, that the neuronal responses are very diverse, and that the preferred directions during cue and delay periods are strongly correlated but tuning widths are not.
Authors:
David Hansel; German Mato
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of neuroscience : the official journal of the Society for Neuroscience     Volume:  33     ISSN:  1529-2401     ISO Abbreviation:  J. Neurosci.     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-01-03     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8102140     Medline TA:  J Neurosci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  133-49     Citation Subset:  IM    
Affiliation:
Laboratory of Neurophysics and Physiology and Institute of Neuroscience and Cognition, University Paris Descartes, 75270 Paris Cedex 06, France, and Comisión Nacional de Energía Atómica and Consejo Nacional de Investigaciones Cientificas y Técnicas, Centro Atómico Bariloche and Instituto Balseiro, 8400 San Carlos de Bariloche, Argentina.
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