Fig. 7: Dissociation of two forms of contextual modulation.

a Population PSTHs for singletons of varying orientation contrasts (color-coded curves) before and after the V4 lesion. V1 near sites with RFs on the singleton were evenly divided into better and worse groups based on their orientation selectivity. Top row: pre-lesion better and worse sites (n = 39 in each group); bottom row: post-lesion better and worse sites (n = 30 in each group). Vertical dashed line at 90 ms marks the division between early and late epochs. b Singleton signal strength in V1 as a function of orientation contrast, comparing early and late epochs (two columns), before and after V4 lesion (two rows), and between better and worse V1 sites (solid and open symbols). Singleton signal strength was computed by directly subtracting the PSTH for 0° contrast from the PSTHs of other contrasts. The resulting differential PSTHs for each orientation contrast were then averaged within the early or late epoch to quantify the singleton signal. The color notations are consistent with those in (a). Source data are provided as a Source Data file.