[PDF][PDF] NMDA receptor contributions to visual contrast coding

MB Manookin, M Weick, BK Stafford, JB Demb - Neuron, 2010 - cell.com
MB Manookin, M Weick, BK Stafford, JB Demb
Neuron, 2010cell.com
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 α cells but substantial in OFF α and δ cells. OFF δ 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 …
Summary
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 α cells but substantial in OFF α and δ cells. OFF δ 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 α and δ cells used NMDA receptors for encoding either the full contrast range (α), including near-threshold responses, or only a high range (δ). However, contrast sensitivity depended substantially on NMDA receptors only in OFF α 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.
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