Model of recurrent inhibition reproduces extra classical receptive field effects in ON parasol cells. A. Spatial frequency tuning of ON parasol cells to full-field sinusoidal drifting gratings (at 4 Hz; n=89), shaded region ± 1 SD. B. Normalized response to central grating pattern, as a function of spatial frequency of a surrounding grating pattern (10 degree center diameter). Each gray line represents a specific central grating frequency (0.77, 0.38, 0.19, 0.1, 0.05, 0.02 cyc/deg; at 4 Hz); black line represents average (n=13 ON parasol cells). C. Refitted GLM simulations of surround suppression using fits of the model to data from the same cells as in panel F (see Methods). Insets on top A–C indicate stimulus.