Figure 2.

Localization of visual responses and orientation selectivity in CO stripes. (A) Cortical surface vasculature indicating the positions of 2 neuroanatomical tracer injections subsequently recovered in the stack of histological sections. (B) CO section corresponding to the imaged region in panel A indicating the borders of CO stripes from one histological section. Narrow white rectangle indicates region evaluated for CO optical density in panel C. The positions of the white arrows correspond to the loci indicated by black arrows in panel C. (C) Relative optical density measured within the white rectangle in panel B. The black arrows indicate the positions of the CO-dense stripes indicated in panel B. (D) Differential image indicating the color-preferring (dark pixels) and luminance preferring (bright pixels) in response to isoluminance red/green gratings minus luminance-contrast gratings summed across 4 orientations. Only the medial portion of the field of view in panel A was imaged in this experimental condition. (E) Single-condition (ΔR/R) image resulting from stimulation with a moving 0° luminance-contrast grating moved in both directions. (F) Single-condition (ΔR/R) image resulting from stimulation with a moving 90° luminance-contrast grating moved in both directions. (G) Differential image of responses to 0° (dark pixels) minus 90° (bright pixels) luminance-contrast gratings. (H) Orientation vector magnitude map illustrating high orientation selectivity (bright pixels) within the thick stripe (white arrow) and in the type-II interstripe medial to it (black arrow). Lower orientation selectivity was exhibited within the 2 thin stripes (gray arrows) and in the type-I interstripe. Small black and white circles indicate the positions of orientation pinwheel centers. (I) Average orientation vector magnitude calculated from the 10% random sampling within each of the 8 CO stripe and interstripe compartments. The highest vector magnitude was exhibited by thick stripe 1 and the lowest orientation selectivity was exhibited by thin stripe 2. (J) Normalized average orientation vector magnitude for each CO stripe-types calculated from the pixel number-weighted average of individual stripes of the same type. As a result, the highest orientation selectivity was observed in the type-II interstripe and the lowest selectivity was observed in the thin stripe. (K) Statistical probability of stripe–stripe comparisons based on the nonparametric Wilcoxon test. The dashed line indicates the P < 0.05 level. Only the interstripe-I versus thin stripe and thick stripe versus interstripe-II comparisons failed to reach statistical significance. Case 2; s06.