A-E: model response to coherent vs. randomized stimulus. Moving edge stimulus is presented (A) and elicits strong response (B). Same stimulus with fixed random permutation of pixels (C) elicits much weaker response (D). (E) compares the total responses in B (red) and D (blue). (F) shows reverse-correlated time courses of the center (blue) and surround (red) inputs to a parasol cell. (G) shows spiking responses of parasol (saturating, blue) and midget cells (linear, red) to input strength.