Pattern ERG of the cat.

Recent reports on pattern ERGs reopened the discussion of pattern or luminance origin of the ERG to pattern reversal stimulation. In this report cat ERGs to checkerboard stimuli were recorded. The stimulus parameters were manipulated in order to vary the strength of local luminance and contrast stimulation independently. Special care was taken to eliminate stray light effects. The results clearly show that pattern specific components in the cat ERG, if present at all, are no greater than the variance of the responses from local luminance nonlinearities. Thus a "Pattern ERG" can be recorded by luminance modulation.