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E.B. Trexler, S.C. Massey; Synaptic components of Rod Bipolar and Cone Bipolar Light Responses in Rabbit Retina Slices. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2195.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Rod bipolars and cone bipolars have different synaptic inputs in both the outer and inner plexiform layer (OPL and IPL). Rod bipolars presumably only get input from rods in the OPL, but they receive GABA input in the IPL. In the OPL, ON cone bipolars get input from cones, which may be coupled to rods. ON cone bipolars are also coupled to AII amacrine cells, which may influence the light response. OFF cone bipolars also get glycinergic input from AIIs, as well as glutamate from rods and cones. We sought to pharmacologically isolate components of bipolar cell light responses to determine the relative contributions of each input. Methods:Bipolar cell light responses were recorded from rabbit retina slices in both voltage clamp and current clamp configurations. Drugs were applied via multibarrel puffer pipettes. The reversal potentials of the excitatory and inhibitory components of the light responses were separated by 50 mV with K–Gluconate patch pipette solutions. Results:Rod bipolars have a depolarizing light response generated from an excitatory and an inhibitory component. The inhibitory component likely originates in the IPL. Cone bipolars have a depolarizing light response that appears to be influenced by spiking AIIs. Inhibitory input was hard to detect, because of coupling to AIIs. OFF cone bipolars have have a depolarizing light response generated from a decrease in an excitatory component and an increase in the inhibitory component. Conclusions:Light responses from bipolar cells are complex and reflect multiple inputs.
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