Spatial selectivity of pattern electroretinogram components.

Pattern electroretinograms were recorded to checkerboard stimuli of various check size to both onset-offset pattern and pattern reversal under most similar conditions of contrast and luminance. With onset-offset pattern the amplitude of the p-q and q-r components of the onset response showed a peak for checks of about 20 min of arc (spatial tuning), whereas the offset response was spatially nonselective at high contrast regardless of the luminance level. With pattern reversal the potentials were similar to those after algebraic summation of onset and offset responses both in waveform and check size of peak amplitude at 50 min of arc. From this we conclude that summation of contrast (onset) and luminance (offset) components is responsible for the shift from 20 min of arc (onset tuning) to 50 min of arc (reversal tuning). The study recommends the application of pattern stimuli in an onset-offset mode for studying antagonistic receptive field properties in the human electroretinogram.