Fig. 7. The response of V1 neurone to ocellar stimuli that changed intensity at different rates. (A) V1 responses at six rates of change; black lines: instantaneous firing rates (see Materials and methods), scale bar, 50 spikes s^-1; red lines: peristimulus spike histograms (5 ms bins); grey lines; time courses of the intensity changes, plotted as LED intensity difference=(left LED output-right LED output), scale bar, 2I_max. Stimuli ramped from -I_max to I_max and then back to -I_max, where I_max=max LED output. (B) The relative modulation, R_mod of V1 (see main text) plotted against the rate of change of ocellar intensity, expressed as I_max s^-1. The data have been normalised to the range of responses between that elicited by a step stimulus (maximum R_mod) and by zero stimulus (minimum, but non-zero R_mod).