A series of experiments addressed the issue of comparability among neurological processes
in pigmented rat and human visual systems. In the first set of experiments, transient visual-
evoked potentials (VEPs) were elicited by the onset of sine-wave gratings of various spatial
frequencies. The spatial frequency-response profiles of the first positive and immediately
succeeding negative components differed from one another, but were similar in the two
species. In addition, amplitude of the negative, but not the positive, component was strongly …