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Encoding of Visual Information by LGN Bursts

Reinagel, Pamela and Godwin, Dwayne and Sherman, S. Murray and Koch, Christof (1999) Encoding of Visual Information by LGN Bursts. Journal of Neurophysiology, 81 (5). pp. 2558-2569. ISSN 0022-3077. http://resolver.caltech.edu/CaltechAUTHORS:20130816-103224935

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Abstract

Encoding of visual information by LGN bursts. Thalamic relay cells respond to visual stimuli either in burst mode, as a result of activation of a low-threshold Ca2+ conductance, or in tonic mode, when this conductance is inactive. We investigated the role of these two response modes for the encoding of the time course of dynamic visual stimuli, based on extracellular recordings of 35 relay cells from the lateral geniculate nucleus of anesthetized cats. We presented a spatially optimized visual stimulus whose contrast fluctuated randomly in time with frequencies of up to 32 Hz. We estimated the visual information in the neural responses using a linear stimulus reconstruction method. Both burst and tonic spikes carried information about stimulus contrast, exceeding one bit per action potential for the highest variance stimuli. The “meaning” of an action potential, i.e., the optimal estimate of the stimulus at times preceding a spike, was similar for burst and tonic spikes. In within-trial comparisons, tonic spikes carried about twice as much information per action potential as bursts, but bursts as unitary events encoded about three times more information per event than tonic spikes. The coding efficiency of a neuron for a particular stimulus is defined as the fraction of the neural coding capacity that carries stimulus information. Based on a lower bound estimate of coding efficiency, bursts had ∼1.5-fold higher efficiency than tonic spikes, or 3-fold if bursts were considered unitary events. Our main conclusion is that both bursts and tonic spikes encode stimulus information efficiently, which rules out the hypothesis that bursts are nonvisual responses.


Item Type:Article
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http://jn.physiology.org/content/81/5/2558.abstractPublisherArticle
Additional Information:Copyright © 1999 The American Physiological Society. Submitted 25 August 1998. Accepted in final form 15 December 1998. Computer programs used to generate stimulus sequences and for preliminary data analysis were generously shared by F. Gabbiani. We are indebted to B. Vaughan for adapting stimulus display software for the experiment. P. Reinagel and C. Koch were supported by the Sloan Foundation Center for Theoretical Neuroscience as well as by the National Institute of Mental Health and National Science Founadation. D. Godwin and S. M. Sherman were supported by the National Institutes of Health.
Group:Koch Laboratory, KLAB
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Funding AgencyGrant Number
Sloan Foundation Center for Theoretical NeuroscienceUNSPECIFIED
National Institute of Mental Health (NIMH) UNSPECIFIED
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Record Number:CaltechAUTHORS:20130816-103224935
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130816-103224935
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ID Code:40506
Collection:CaltechAUTHORS
Deposited By: KLAB Import
Deposited On:11 Jan 2008 04:38
Last Modified:19 Nov 2015 00:44

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