DESCRIPTION (provided by applicant): GABAergic and glycinergic inhibitory pathways in the inner plexiform layer modulate the flow of visual information between bipolar cells and ganglion cells and are an essential element in retinal information processing. In mammalian retina the precise roles of the different inhibitory neurotransmitters, receptor subtypes and circuits are not well understood. Different bipolar cell types separate the visual signal into distinct visual channels, e.g., rod versus cone, on versus off and sustained versus transient signals. Distinct GABAA and GABAC receptors found on bipolar cell terminals have been shown to have different biophysical properties and are present in different proportions on distinct cell types. Glycine receptors have also been shown to be present on bipolar cell terminals, but their functional roles on most bipolar cells is unclear. The goal of the proposed study is to analyze the role of GABAergic and glycinergic inhibition of bipolar cell terminals on spatial and temporal processing in the IPL. We will measure the light-evoked inhibitory signals in different bipolar cell types to determine whether these distinct receptor types mediate unique inhibitory signals and whether the distinct bipolar cell signaling pathways utilize distinct inhibitory signals, which affects transmission from bipolar cells to third order cells