Fig. 3. Comparison of electrically-evoked RGC spikes between single-pulse and burst stimulation in the RD retina.
(A) Left inset: MEA positions of the stimulation (channel 52, marked with a red dot) and recording (channel 53, marked with a yellow dot) electrodes spaced 200 μm apart. Left panel: Typical responses of the RD RGC to single-pulse stimulation are shown as raster plots. Electrically-evoked RGC spikes are highlighted. The time window for the raster plots is set to ± 0.1 sec, with 0 sec representing the stimulus onset (red dashed line). For each raster plot (10 trials), the pulse amplitude increases from top to bottom (10–50 μA). The pulse duration is fixed at 250 μs/phase. Middle panel: Typical responses of the RD RGC to burst stimulation are shown as raster plots. For each raster plot, the pulse number increases from top to bottom (#1–#5). Right panel: RGC response curves to single-pulse and burst stimulation in RD RGCs located 200 μm away from the stimulation electrode. Error bars represent the standard error of the mean (SEM). Statistical differences in response curves are indicated by asterisks (*p < 0.05, **p < 0.01). (B) Left and Middle panels: same representative raster plots of RD RGCs located 600 μm away from the stimulation electrode. Right panel: RGC response curves to single-pulse and burst stimulation in RD RGCs located 600 μm away from the stimulation electrode. Statistical differences in the graphs are indicated by asterisks (*p < 0.05, **p < 0.01). (C) Changes in normalized responses with the distance between stimulation and recording electrodes. Left panel: single-pulse stimulation. The inset (spatial MEA color map) shows the normalized RGC responses in one representative retinal patch upon electrical stimulation with a pulse amplitude of 50 μA. The red dot indicates the location of the stimulation electrode. Right panel: burst stimulation. The inset (spatial MEA color map) shows the normalized RGC responses in one representative retinal patch upon electrical stimulation with five pulses per burst. RGC, retinal ganglion cell; RD, retinal degenerate; MEA, multi-electrode array.
© Korean J Physiol Pharmacol
