Figure 7

Elevated RGC Density and Relative Overrepresentation of Diffuse ON-RGCs in the SZ

(A and B) Density maps of all RGCs (A) and ACs (B) computed from cell counts in Figures S6A–S6C, from n = 1 retina. D, dorsal; N, nasal; SZ, strike zone; T, temporal; V, ventral.

(C) Projections of RGC densities from (A) into binocular visual space during hunting (eyes converged), as illustrated in the inset. Note that the two SZs neatly superimpose (see also [27]).

(D) Illustration of photoconversion and pre-processing pipeline for digitizing single RGC morphologies. Left: following photoconversion, cells were imaged as stacks under two-photon (green) in the background of BODIPY staining to demarcate the IPL borders (red). Cells were then thresholded and manually “cleaned” where required prior to automatic detection of image structures and alignment relative to the IPL borders. The resultant “point clouds” were used to determine summary statistics of each cell (e.g., E–M) and were also projected into density maps for visualization (Figure S6G). Right: three further examples of photoconverted RGCs are shown.

(E–M) A total of n = 64 and n = 67 randomly targeted RGCs from the SZ and nasal retina, respectively, were processed for further analysis, which included computation of their dendritic tilt (E–H), stratification widths within the IPL (I–K), en face dendritic field area (L), and total number of detected dendritic structures (“points”; M; STAR Methods). The dendrites of nasal (purple) and SZ (pink) RGCs both tended to tilt toward the eye’s dorsal pole (E: schematic; F: soma-aligned data of all dendrites’ center of mass). Dendritic tilt was quantified in soma-centered polar coordinates based on the Cartesian x,y,z coordinates that emerge from the original image stacks (G), such that r: distance in microns between soma and dendritic center of mass (Figure S6D), θ (0°:90°): strength of the dendritic tilt (0° and 90° denoting no tilt and maximal positive tilt, respectively; Figure S6E), and ϕ (0°:360°): direction of the dendritic tilt in approximately retinotopic space (approximate as the eye is curved). ϕ significantly differed between nasal and SZ RGCs (H). For summarizing widths, RGCs were considered as a single group (I) or split into On and Off RGCs (J and K, respectively), based on the IPL depths of their dendritic center of mass (here, the upper third of the IPL was considered “Off” and the bottom two-thirds were considered “On”). Kolmogorov-Smirnov test for circular statistics (H) and Wilcoxon rank sum test, 1 tailed (I–M), is shown.