Figure 6.

Responses to various start angles of PM relative to AM in sign-selective units. A, This unit was Df <0 selective and responded most strongly when PM was offset by values near that of a natural Df <0 stimulus (270°). The fitted function is of the form y = M + Acos(t - t₀) (r² = 0.44; p < 0.01). B, This unit was Df >0 selective and responded most strongly when PM was offset by values near that of a natural Df >0 stimulus (90°). The fitted function is of the same form in A (r² = 0.72; p < 0.00001). C, Ten responses from nine units to the same start angles shown in A and B, shifted to show the relative distance between the AM and PM mean vector angles and then binned into 20° segments. Spike rate is normalized to the spike rate in response to AM alone (mean ± SEM), with a fitted function of the same form in A and B (r² = 0.91; p < 0.0000001).