Neural responses to corner-folds depend on corner angle.

(A) Population data of midpoint corner-fold responses versus absolute baseline activity. Blue points represent responses from individual V1 neurons to corner-folds of three different angles (S90°, S52° and S40°) and to the non-corner gradient (P180°). P180° and S90° were in the Square and Edge stimulus (N = 25), S52° was in the Star stimulus (N = 30), and S40° was in the Corners stimulus (N = 28). The midpoint fold response and absolute baseline activity of each neuron yields the ordinate and abscissa in logarithmic scale of each data point in the scatter plot. The dotted line of unit slope indicates equality between midpoint fold response and absolute baseline activity. The red cross is the mass center of data points. For all folds, most data points and all mass centers fall above the line, indicating a predominance of elevation of midpoint fold response above absolute baseline activity. Furthermore, the length of the yellow vertical line from the mass center to the dotted line of unit slope indicates the average spike rate difference, i.e. the difference: midpoint fold response–absolute baseline activity. The smaller the fold angle, the longer the vertical line, indicating stronger increase of midpoint fold response. (B) Spike rate difference for each of the fold responses. As in (A), the average spike rate difference decreases with increasing fold angle. Error bars represent the SEM. * indicates a significant difference (Wilcoxon rank sum test corrected for multiple comparisons with the Benjamini and Hochberg method [18]) between responses (* p p p S1 Table for exact p-values).