Simultaneously Recorded Retinal and Cortical Responses to Patterned Stimuli*

The method of stimulus alternation was used to record simultaneously electroretinograms (ERGs) and visually evoked cortical potentials (VECPs) to stimuli of differing luminance and pattern. Stimuli consisted of checked and striped patterns with a variety of spatial frequencies. ERGs of approximately equal amplitudes were elicited by patterns of the same spatial frequency regardless of pattern. ERG amplitude decreased monotonically with increasing spatial frequencies of the patterns. Simultaneously recorded VECPs were consistently larger for checked patterns than for striped patterns of equal spatial frequency. The largest VECPs were seen with checked patterns having spatial frequencies of approximately 1 cycle/deg of visual angle: frequencies both higher and lower than this value produced smaller responses.