Abstract
In the retina, it is not well understood how visual processing depends on AMPA- and NMDA-type glutamate receptors. Here we investigated how these receptors contribute to contrast coding in identified guinea pig ganglion cell types in vitro. NMDA-mediated responses were negligible in ON alpha cells but substantial in OFF alpha and delta cells. OFF delta cell NMDA receptors were composed of GluN2B subunits. Using a novel deconvolution method, we determined the individual contributions of AMPA, NMDA, and inhibitory currents to light responses of each cell type. OFF alpha and delta cells used NMDA receptors for encoding either the full contrast range (alpha), including near-threshold responses, or only a high range (delta). However, contrast sensitivity depended substantially on NMDA receptors only in OFF alpha cells. NMDA receptors contribute to visual contrast coding in a cell-type-specific manner. Certain cell types generate excitatory responses using primarily AMPA receptors or disinhibition.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Contrast Sensitivity / drug effects
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Contrast Sensitivity / physiology*
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Dizocilpine Maleate / pharmacology
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Electric Conductivity
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Excitatory Amino Acid Agonists / pharmacology
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Excitatory Amino Acid Antagonists / pharmacology
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Gene Expression Regulation / drug effects
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Gene Expression Regulation / physiology
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Guinea Pigs
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In Vitro Techniques
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Light
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Mice
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Mice, Inbred C57BL
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N-Methylaspartate / pharmacology
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Patch-Clamp Techniques / methods
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Photic Stimulation / methods
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Piperidines / pharmacology
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Receptors, N-Methyl-D-Aspartate / genetics
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Receptors, N-Methyl-D-Aspartate / metabolism*
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Retina / drug effects
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Retina / physiology*
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Retinal Ganglion Cells / classification
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Retinal Ganglion Cells / drug effects
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Retinal Ganglion Cells / metabolism
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Visual Perception / drug effects
Substances
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Excitatory Amino Acid Agonists
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Excitatory Amino Acid Antagonists
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Piperidines
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Receptors, N-Methyl-D-Aspartate
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N-Methylaspartate
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Dizocilpine Maleate
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ifenprodil