Figure 7. Matching with multiple anatomical and physiological features. A, βIII-Tubulin immunolabeling, focused at level of RGC somas. Black nuclei surrounded by bright somal labeling mark cell locations. Bright striate labeling marks axon fascicles passing in and out of image plane. Some primary cellular processes are visible until they pass out of image plane. Putative parasol RGCs identified based on gross morphology (see text) marked with white diamonds. B, C, Highlighted areas from A, focused at level of axon initial segments. Immunolabeling for ankyrin-G marks multiple axon initial segments. DAPI marks nuclei, including many tubulin negative cells, putative amacrine cells, and blood vessels. White arrows show vector defined for a putative ON (B) and OFF (C) parasol cell, from the somal center to the center of the axon initial segment. Scale bar, 15 μm. D, E, Electrical images, putatively matching the cells in B, C. Color of each electrode disc indicates the timing of its peak negative signal relative to the time of the maximal amplitude somal spike. Black arrows show vector defined as pointing from the somal spike center of mass to the earlier peaking putative initial segment location. F, 2D histogram of linear assignment analysis (see text). The entire space of possible assignments was probed between anatomical and electrical image vectors for 14 putative parasol cells. Color shows density of possible assignments yielding cost metrics with the given amplitudes. Inset, The lower left extreme points, near optimal for both cost metrics. Global optimum circled in red. G, H, Same area as shown in A, focused on the primary dendritic elaborations of the ON (G, dashed yellow circles) and OFF (H, blue circles) parasol populations, as identified by the optimal point in F. Clean mosaic tiling confirms identification. ON parasol arbors lie closer to the RGC layer than OFF parasol arbors, as evident from additional somas still slightly in plane in G. Scale bar, 50 μm also applies to A.