Computational studies are challenging the intuitive view that neurons with broad tuning curves are necessarily less discriminative than neurons with sharp tuning curves. In the context of somatosensory processing, broad tuning curves are equivalent to large receptive fields. To clarify the computational role of large receptive fields for cortical processing of somatosensory information, we recorded ensembles of single neurons from the infragranular forelimb/forepaw region of the rat primary somatosensory cortex while tactile stimuli were separately delivered to different locations on the forelimbs/forepaws under light anesthesia. We specifically adopted the perspective of individual columns/segregates receiving inputs from multiple body location. Using single-trial analyses of many single-neuron responses, we obtained two main results. 1) The responses of even small populations of neurons recorded from within the same estimated column/segregate can be used to discriminate between stimuli delivered to different surround locations in the excitatory receptive fields. 2) The temporal precision of surround responses is sufficiently high for spike timing to add information over spike count in the discrimination between surround locations. This surround spike-timing code (i) is particularly informative when spike count is ambiguous, e. g., in the discrimination between close locations or when receptive fields are large, (ii) becomes progressively more informative as the number of neurons increases, (iii) is a first-spike code, and (iv) is not limited by the assumption that the time of stimulus onset is known. These results suggest that even though large receptive fields result in a loss of spatial selectivity of single neurons, they can provide as a counterpart a sophisticated temporal code based on latency differences in large populations of neurons without necessarily sacrificing basic information about stimulus location.
Computational role of large receptive fields in the primary somatosensory cortex
Creators
Guglielmo Foffani - Drexel University
John K. Chapin - SUNY, Dept Physiol, Brooklyn, NY USA
Karen A. Moxon - Drexel Univ, Sch Biomed Engn Sci & Hlth Syst, Philadelphia, PA 19104 USA
Publication Details
Journal of neurophysiology, v 100(1), pp 268-280
Publisher
Amer Physiological Soc
Number of pages
13
Grant note
2P50NS-24707 / NINDS NIH HHS; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Institute of Neurological Disorders & Stroke (NINDS)
P50NS024707 / NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Institute of Neurological Disorders & Stroke (NINDS)
Resource Type
Journal article
Language
English
Academic Unit
School of Biomedical Engineering, Science, and Health Systems
Web of Science ID
WOS:000257635400024
Scopus ID
2-s2.0-53949096562
Other Identifier
991019169811804721
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