(A) Responses (ΔF/F0, mean ± SE) of three example neurons to grating stimuli. (B) Scatterplot of neurons’ maximum responses to concentric and radial gratings against Cartesian gratings. 48.4% of 535 neurons recoded in the imaging area showed significantly stronger responses to concentric or radial gratings (red, n = 11 for monkey A, and n = 8 for monkey B, one-way ANOVA, p<0.05). Only 2.2% showed significantly stronger responses Cartesian gratings (blue). Black indicates no significant preference (p≥0.05). (C) Histogram of neurons’ optimal Cartesian gratings spatial frequencies. Neuronal responses to its optimal Cartesian gratings at spatial frequencies of 1, 2, and 4 cycle/° were compared using one-way ANOVA (p<0.05).