Figure 4.

Characteristics of CatCh-Mediated Light Responses at 3 Months Post-Injection

(A) Two-photon images of the peri-foveolar region of NHP1, injected with AAV2-hCatCh-GFP displaying the high density of transfected cells with membrane-bound expression. The white dotted square on the left indicates the area displayed at higher magnification on the right. (B) Retinal slice showing the peri-foveolar region of NHP2 injected with AAV2-hCatCh (no GFP tag), where light-responsive ganglion cells were recorded. Recordings in the cell-attached mode show spikes and their increase in frequency during light stimulation. Typical spiking response and photocurrent of cells recorded in cell-attached or whole-cell patch-clamp configuration, respectively. Scale bars in (A) and (B) represent 20 μm. (C) Average spectral tuning at 10¹⁷ photons/cm²/s after application of L-AP4 in primate retinas expressing hCatCh. (D) Average normalized response to different stimulus intensities. (E) Raster plot and peri-stimulus time histogram of ganglion cell responses to full-field flashes at 480 nm after application of L-AP4 in primate retina injected with AAV2-SNCG-hCatCh-GFP. (F) Grayscale maps based on firing rates of responding neurons (expressed as a percentage of their spontaneous activity) at increasing light intensities in primate retinas injected with AAV2-SNCG-hCatCh-GFP (top) and AAV2-SNCG-hCatCh (bottom) at a 5 × 10¹¹ vg per eye dose. The macular area is indicated by dashed green lines and the black dots represent the locations of the MEA recording electrodes. The scale bar represents 200 μm. (G) The macular region of NHP1 prior to dissection, showing CatCh expression in the peri-foveolar ring. (H) Half of the foveal ring as indicated by the white rectangle in (G), after MEA recordings and RGC immunolabeling. The retinal flat mount was stained with Brn3a (red) and GFP antibodies (green). (I) The foveal region of retina from NHP2 [shown in the lower right panel of (F)] after labeling with antibodies against channelrhodopsin (green). Nuclei were stained with DAPI. Scale bars in (H) and (I) represent 50 μm. Error bars represent SEMs.