Figure 8.

Selectivity and nonlinear spatial summation in response to grating stimuli. A, The average spike rate of 10 simultaneously recorded ON-OFF PACs to drifting sinusoidal grating patterns (96% contrast) is shown as a heat map, as a function of the spatial and temporal frequency of the grating. B, Same as A, for 123 simultaneously recorded OFF parasol cells. Parasol cell responses were strongest at lower spatial frequencies than those of PACs. C, The average response amplitude of PACs in response to modulation of a stationary sinusoidal grating pattern is shown as a function of grating spatial frequency. The component of the response at the F1 (black) is shown separately from the component at twice the fundamental frequency (i.e., the F2, red). The error bars represent ±1 SEM (n = 5). D, Same as C, for simultaneously recorded OFF parasol cells (n = 52).