Fig. 2. Differential laminar distribution of BHA and MUA across experiments in V1.

(A to D) present V1 data from recordings during diffuse flash stimulation (V1-DF; n = 104 experiments in two animals). (E to H) Data from V1 recordings during free-viewing exploration of visual images [V1-FV; n = 49, same two animals as in (A to D)]. Line plots show the time course of BHA (A and E) and MUA (C and G) response across supragranular, granular, and infragranular (red, green, and blue lines) layers. x axes indicate time relative to stimulus (A, C) or fixation onset (E, G). y axes represent signal change from baseline (i.e., normalized BHA/MUA). Box plots present BHA (B and F) and MUA (D and H) distributions averaged across time after stimulus onset (B and D) and across the entire pre- and postfixation epoch (F and H). Supragranular, granular, and infragranular (S, G, and I) layers are plotted as separate box plots. Box plots indicate 25th percentile, median, and 75th percentile; whiskers extend to extreme values not considered outliers, while outliers are marked with crosses. Shading in line plots reflects SEM. Note the consistently different laminar distributions of BHA and MUA in both experiments. Despite different stimuli, levels of firing, and BHA magnitude across experiments, BHA in the supragranular layers is enhanced relative to that in the granular and infragranular layers, while MUA in supragranular is sparse compared to granular and infragranular. Note also that in the free viewing (E to H), there is substantial saccadic modulations of MUA and BHA across all layers, with a clear pattern of MUA suppression around the time of the saccade (perisaccadic suppression) and MUA increase at the end of the saccade (onset of fixation). Arrows in (A and E) indicate early (solid line) and late (dashed line) BHA components.