Cell type classification and RFs at single cone resolution. (a) RFs of 323 RGCs recorded simultaneously from isolated macaque retina were measured using reverse correlation with white noise stimuli. Central panel: RF radius vs. first principal component of response time course; clusters reveal distinct cell types. Surrounding panels: Gaussian fits to RFs of cells from each cluster, superimposed on electrode array outline. Outer panels: fine-grained spatial RF profiles for highlighted cells. Scale bars: 60 μm. (b) First and second panels show spatial RF profiles of two cells, with putative locations of cones (black dots) identified by thresholding. Third panel shows the putative cone map accumulated across cells. Fourth panel shows putative cone map overlaid on a photograph of cone outer segments labeled with peanut agglutinin.

Cone type identification and inputs to RGCs. (a) The spectral sensitivity of cones providing input to two cells is represented by the relative magnitude of the red, green and blue STA values at their locations. (b) For every cone in one recording, these values are shown as points on a sphere. Colored lines indicate spectral sensitivity of macaque cones. Point color indicates classification as L (red), M (green), or S (blue). (c) L/M cone discriminability quantified by projection along the line joining L and M loci. Bars color indicates classification. S cones excluded. (d) Assembled cone mosaic from all RGCs over a region. Cones from (a) are circled. (e) Full mosaic of 2,373 cones from one recording. (f) Cone mosaic overlaid on STA, revealing strength of cone inputs. (g) Weaker cone inputs in RF surround revealed by truncating positive values and renormalizing. (h) Connectivity diagram, with line thickness proportional to strength of each cone input. Surround (black) line thicknesses were increased five-fold relative to center (white) line thicknesses for visibility.

Full functional sampling of cone lattice by four RGC types. Each panel shows cones identified in a single recording (red, green and blue dots) sampled by RF centers of RGCs of a single type. Cones are identical in all panels. Cones providing input to at least one RGC are highlighted with an annulus. Scale bar: 50 μm.

Cone type specificity. (a) ON midget cell lacking input from nearby S cones (arrows). (b,c) OFF midget cells receiving input from these cones. (d) Frequency of strong S cone sampling by each cell type. (f,g) Two midget cells with relatively pure L/M cone input. (h) Midget cell with mixed L/M input. (e) Normalized L,M,S cone inputs to all midget cells in one recording, obtained with cone-isolating stimuli. Abscissa: M/(|L|+|M|+|S|), ordinate: L/(|L|+|M|+|S|). Diagonals: no S cone input. Upper-right and lower-left quadrants: same-sign (non-opponent) L/M input. Lower-right and upper-left quadrants: opposite-sign (opponent) L/M input. Letters: cells from previous panels. (i) Purity index schematic. (j) (Top) Purity index for ON and OFF midget cells in one recording; width (SD) 0.45, 0.44 respectively. (Bottom) Purity index after random permutation of L/M cones; width 0.37±0.04, 0.36±0.04 respectively (mean ± 2 SD across permutations). (k) Comparison of purity distribution width in data and permutations. Each point represents >50 simultaneously recorded ON or OFF midget cells. Error bars: 1 SD across permutations. (l) As (k), using cones from RF surround. (m) Using random cone mosaics with clumping matched to data. (n) Using binarized cone weights (0,1). (o) Using random permutation of cone weights in RF center.