Fig. 6: Ex vivo retinal experiments for evaluating the effectiveness of μETF MEA for subretinal stimulation.
a Schematic illustration of calcium imaging setup for monitoring retinal activation and b its side and top views of the retina chamber with MEAs. c Expression of genetically encoded calcium indicator confirmed by immunofluorescence images of sRGECO (mCherry), DAPI, and merged one. Scale bar: 20 μm. d Relative location of RGCs around stimulation electrode for evaluation of stimulation threshold and stimulation resolution. e Responses of retinal ganglion cells in response to increasing electrical stimulation from protruding and planar electrodes, within the dotted line for threshold defined as a half of (ΔF/F0)max. f Comparison of stimulation thresholds of protruding and planar electrodes, using Wilcoxon rank-sum test (p = 0.0175). g Spatial extent of electrical activation depending on distances from the center of stimulating electrode (I = 20 μA). In f, g, each dot represents activation of a retinal ganglion cell, and calcium intensities were normalized to the maximum (steady-state) of fitting functions (See Methods section for detail).
