Document Detail

Retinal synaptic pathways underlying the response of the rabbit local edge detector.
MedLine Citation:
PMID:  20457864     Owner:  NLM     Status:  MEDLINE    
We studied the circuitry that underlies the behavior of the local edge detector (LED) retinal ganglion cell in rabbit by measuring the spatial and temporal properties of excitatory and inhibitory currents under whole cell voltage clamp. Previous work showed that LED excitation is suppressed by activity in the surround. However, the contributions of outer and inner retina to this characteristic and the neurotransmitters used are currently unknown. Blockage of retinal inhibitory pathways (GABA(A), GABA(C), and glycine) eliminated edge selectivity. Inverting gratings in the surround with 50-microm stripe sizes did not stimulate horizontal cells, but suppressed on and off excitation by roughly 60%, indicating inhibition of bipolar terminals (feedback inhibition). On pharmacologic blockage, we showed that feedback inhibition used both GABA(A) and GABA(C) receptors, but not glycine. Glycinergic inhibition suppressed GABAergic feedback inhibition in the center, enabling larger excitatory currents in response to luminance changes. Excitation, feedback inhibition, and direct (feedforward) inhibition responded to luminance-neutral flipping gratings of 20- to 50-microm widths, showing they are driven by independent subunits within their receptive fields, which confers sensitivity to borders between areas of texture and nontexture. Feedforward inhibition was glycinergic, its rise time was faster than decay time, and did not function to delay spiking at the onset of a stimulus. Both the on and off phases could be triggered by luminance shifts as short in duration as 33 ms and could be triggered during scenes that already produced a high baseline level of feedforward inhibition. Our results show how LED circuitry can use subreceptive field sensitivity to detect visual edges via the interaction between excitation and feedback inhibition and also respond to rapid luminance shifts within a rapidly changing scene by producing feedforward inhibition.
Thomas L Russell; Frank S Werblin
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, N.I.H., Extramural     Date:  2010-03-24
Journal Detail:
Title:  Journal of neurophysiology     Volume:  103     ISSN:  1522-1598     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2010 May 
Date Detail:
Created Date:  2010-05-12     Completed Date:  2010-08-25     Revised Date:  2013-05-29    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2757-69     Citation Subset:  IM    
Division of Neurobiology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA.
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MeSH Terms
Action Potentials / drug effects,  physiology
Feedback, Physiological / drug effects
GABA-A Receptor Antagonists
Neural Inhibition / drug effects,  physiology
Neural Pathways / drug effects,  physiology
Neurons / drug effects,  physiology
Patch-Clamp Techniques
Photic Stimulation
Receptors, GABA / metabolism*
Receptors, GABA-A / metabolism*
Receptors, Glycine / antagonists & inhibitors,  metabolism*
Retina / drug effects,  physiology*
Retinal Bipolar Cells / drug effects,  physiology
Retinal Horizontal Cells / drug effects,  physiology
Synapses / drug effects,  physiology*
Time Factors
Vision, Ocular / drug effects,  physiology*
Grant Support
Reg. No./Substance:
0/GABA-A Receptor Antagonists; 0/GABA-C receptor; 0/Receptors, GABA; 0/Receptors, GABA-A; 0/Receptors, Glycine

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