Relative contributions of bipolar cell and amacrine cell inputs to light responses of ON, OFF and ON-OFF retinal ganglion cells.
Light-evoked postsynaptic currents (lePSCs) were recorded from ON, OFF and ON-OFF ganglion cells in dark-adapted salamander retinal slices under voltage clamp conditions, and the cell morphology was examined using Lucifer yellow fluorescence with confocal microscopy. The current-voltage relations of the lePSCs in all three types of ganglion cells are approximately linear within the cells' physiological range. The average chloride/cation conductance ratio (Deltag(Cl)(NR)/Deltag(C)(NR)) of the lePSCs is near 3, suggesting that ganglion cell light responses are associated with a greater postsynaptic conductance change at the amacrine-ganglion cell inhibitory synapses than at the bipolar-ganglion cell excitatory synapses. By comparing the charge transfer of lePSCs in normal Ringer's and in picrotoxin+strychnine+Imidazole-4-acidic acid, we found that the GABAergic and glycinergic amacrine-bipolar cell feedback synapses decreased the light-induced glutamatergic vesicle release from bipolar cells to all ganglion cells, and the degree of release reduction varied widely from ganglion cell to ganglion cell, with a range of 3-28 fold.
Pang
Ji Jie
JJ
Cullen Eye Institute, Baylor College of Medicine, One Baylor Plaza, NC-205, Houston, TX 77030, USA.
Gao
Fan
F
Wu
Samuel M
SM
D000559:Ambystomatidae; D000818:Animals; D002712:Chlorides / Q000502:physiology; D004553:Electric Conductivity; D017950:Ganglia, Sensory / Q000502:physiology*; D007093:Imidazoles / Q000494:pharmacology; D018613:Microscopy, Confocal; D018408:Patch-Clamp Techniques; D010852:Picrotoxin / Q000494:pharmacology; D012160:Retina / Q000502:physiology*; D013331:Strychnine / Q000494:pharmacology; D009435:Synaptic Transmission / Q000502:physiology; D014785:Vision, Ocular / Q000502:physiology*
D002712:Chlorides; D007093:Imidazoles; D010852:Picrotoxin; D013331:Strychnine