| A Mammalian Retinal Bipolar Cell Uses Both Graded Changes in Membrane Voltage and All-or-Nothing Na+ Spikes to Encode Light. | |
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MedLine Citation:
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PMID: 22219291 Owner: NLM Status: In-Data-Review |
Abstract/OtherAbstract:
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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. |
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Authors:
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Shannon Saszik; Steven H Devries |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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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:
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Created Date: 2012-01-05 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8102140 Medline TA: J Neurosci Country: United States |
Other Details:
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Languages: eng Pagination: 297-307 Citation Subset: IM |
Affiliation:
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Departments of Ophthalmology & Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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