Fig. 3.

Stimulation of surround reduces direction selectivity: histograms showing stimulus trials binned according to the number of spikes generated in a representative guinea pig On-Off DSGC in response to narrow and wide bars at 20% contrast. x-Axis represents number of spikes per trial, and y-axis represents number of trials. In some panels the zero-spikes bin has been truncated to more clearly show the positive-response trials. The bar was moving in the preferred and null directions at velocities from 25 μm/s to 6,400 μm/s. Responses to null- and preferred-direction motion are better separated for On responses than for Off responses.