Document Detail


A mammalian retinal bipolar cell uses both graded changes in membrane voltage and all-or-nothing Na+ spikes to encode light.
MedLine Citation:
PMID:  22219291     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Barlow (1953) studied summation in ganglion cell receptive fields and observed a fine discrimination of spatial information from which he inferred that retinal interneurons use analog signals to process images. Subsequent intracellular recordings confirmed that the interneurons of the outer retina, including photoreceptors, horizontal cells, and bipolar cells, respond to light with slow, graded changes in membrane potential. Analog processing may enable interneurons to discriminate fine gradations in light intensity and spatiotemporal pattern, but at the expense of the speed, temporal precision, and threshold discrimination that are characteristic of all-or-nothing Na(+) spikes. We show that one type of mammalian On bipolar cell, the ground squirrel cb5b, has a large tetrodotoxin (TTX)-sensitive Na(+) current. When recorded from in the perforated patch configuration, cb5b cells can signal the onset of a light step with 1-3 all-or-nothing action potentials that attain a peak amplitude of -10 to -20 mV (peak width at half-height equals 2-3 ms). When exposed to a continuous, temporally fluctuating stimulus, cb5b cells generate both graded and spiking responses. Cb5b cells spike with millisecond precision, selecting for stimulus sequences in which transitions to light are preceded by a period of darkness. The axon terminals of cb5b bipolar cells costratify with the dendrites of amacrine and ganglion cells that encode light onset with a short latency burst of spikes. The results support the idea that a spiking On bipolar cell is part of a dedicated retinal pathway for rapidly and reliably signaling dark to light transitions.
Authors:
Shannon Saszik; Steven H DeVries
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of neuroscience : the official journal of the Society for Neuroscience     Volume:  32     ISSN:  1529-2401     ISO Abbreviation:  J. Neurosci.     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-01-05     Completed Date:  2012-02-22     Revised Date:  2014-09-15    
Medline Journal Info:
Nlm Unique ID:  8102140     Medline TA:  J Neurosci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  297-307     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Action Potentials / physiology*,  radiation effects
Animals
Cell Membrane / physiology*,  radiation effects
Female
Light
Male
Mammals
Organ Culture Techniques
Photic Stimulation / methods
Retinal Bipolar Cells / physiology*,  radiation effects
Sciuridae
Sodium Channels / physiology*,  radiation effects
Vision, Ocular / physiology*,  radiation effects
Grant Support
ID/Acronym/Agency:
EY15967/EY/NEI NIH HHS; EY18204/EY/NEI NIH HHS; R01 EY018204/EY/NEI NIH HHS; R01 EY018204-05/EY/NEI NIH HHS
Chemical
Reg. No./Substance:
0/Sodium Channels
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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