Responses to drifting sine gratings at two different orientations, −15° (gray) and −45° (white). Fits of the normalization model (curves) were performed on a larger data set than shown, which included 72 stimulus conditions (8 contrasts, 3 orientations, and 3 temporal frequencies). A, Period histograms. Rowscorrespond to different contrasts, columns to different orientations. B, C, Response amplitude and phase as a function of contrast. To facilitate comparison in C the responses to each grating were shifted vertically so that the values predicted by the model would overlap. D, Polar plot of the responses in B and C. Cell 392l009 (DI = 0.5; SF = 0.4; SZ = 2.2), experiment 8; N = 3. Parameters: τ0 = 28 msec; τ1 = 3 msec;n = 1.6.
