Fig. 4: Single-pixel stimulation of retinal ganglion cells.

a Sketch of the recording setup. b, c Representative responses from a retinal ganglion cell upon three consecutive light pulses (560 nm, 10 ms, 0.9 mW mm⁻²) with large-field illumination (b) and single-pixel illumination (c). The green triangles correspond to the onset of each pulse. d, e Comparison of the stimulation efficacy during large-field (d) and single-pixel (e) illumination under increasing irradiances with Ti-based (n = 20 RGCs, mean ± s.e.m.) and TiN-based pixels (n = 21 RGCs, mean ± s.e.m.). f Change in the activation threshold from large-field to single-pixel illumination for both Ti pixels (n = 20 RGCs) and TiN-coated pixels (n = 21 RGCs). The numbers for each column are the fraction of RGCs activated by a 10-ms light pulse of 0.9 mW mm⁻². Inf means that the RGC does not show ML activity at any of the irradiance levels tested. LF large-field, SP single-pixel. g ML firing rate (n = 30 RGCs, mean ± s.e.m.) at low irradiance levels for TiN-coated pixels and single-pixel illumination. The black line is the second-order polynomial interpolation (R² = 0.29). The grey dashed lines show the activation threshold computed as the irradiance eliciting 10% of the maximal ML firing rate at 0.9 mW mm⁻². The right axis shows the quantification of the average numbers of spikes elicited per light pulse. h Activation threshold for each RGCs with single-pixel illumination and TiN-coated pixels (mean ± s.d.). i ML firing rate (n = 11 RGCs, mean ± s.e.m.) at low irradiance levels for TiN-coated pixels and single-pixel illumination before and after the application of DL-AP4. j Activation threshold for each individual RGC with single-pixel illumination and TiN-coated pixels before (black circles) and after (white circles) the application of DL-AP4 (mean ± s.d.).