Fig. 3: Postsynaptic currents evoked in ON DSGCs by optogenetic activation of VGluT3 cells.
From: A circuit suppressing retinal drive to the optokinetic system during fast image motion
a Inhibitory currents (holding voltage Vhold: +20 mV) in two ON DSGCs (left and right panels) in response to optogenetic stimulation during the period marked by interrupted vertical lines. Blue traces were acquired under photoreceptor (PR) block consisting of L-AP4, ACET and hexamethonium. Pharmacological blockade first of glutamate receptors (red) and then of glycine receptors (orange) show that the current is glycine mediated. Current traces were averaged over 3–5 repeated trials and smoothed. b Summary of optogenetically evoked inhibitory (outward) currents in ON DSGCs. Peak currents are shown for stimulation durations of 1 s (8 cells) or 0.1 s (5 cells), along with their mean ± SEM. Throughout Fig. 3, the dotted line and shaded region represent the noise level (mean ± SD over cells, see “Methods”). c Summary of 3-step pharmacology experiments where the photoreceptor block was followed by glutamate (CNQX, D-AP5), and then glycine blockade (strychnine). Colors are as in (a) (4 cells with mean ± SEM, peak currents were normalized by the control value). d As for panel (a), but with glycinergic blockade (purple) preceding glutamatergic blockade. e As for panel (c), but summarizing experiments with glycine blockade preceding glutamate blockade, as in (d) (3 cells). f Optogenetic activation of VGluT3 cells evokes inhibitory currents in a suppressed-by-contrast RGC (top panel; Vhold: +20 mV), and excitatory currents in an ON-OFF DSGC (bottom panel; Vhold: −65 mV; both under photoreceptor block). g Excitatory currents evoked in an ON DSGC by optogenetic activation of VGluT3 cells and the pharmacological effects on this current in the same cell. Vhold: −65 mV. Colors are as in (d). h Summary of optogenetically evoked excitatory (inward) currents in ON DSGCs (peak currents, mean ± SEM; 8, 4 cells for 1 s, 0.1 s stimulation, respectively). i Peak inward currents in the ON DSGC shown in (g). The dotted line represents noise for the cell. Colors in (e), (g), (i) are as in (d). Source data are provided as a Source data file.
