ROD TEMPORAL CHANNELS

Mechanisms underlying rod temporal contrast sensitivity have been cons idered in terms of a fast retinal signal predominating at mesopic leve ls and a slower retinal signal predominating at scotopic levels. Here we use a small signal masking method, which has previously been used t o delineate the cone-mediated cortical temporal channels, to investiga te their rod-mediated cortical counterparts. The results suggest that there are three different rod-mediated cortical temporal channels, one which is lowpass and two which are bandpass, These mechanisms co-exis t at all light levels and their relative sensitivity depend on the sti mulus spatio-temporal frequency.