Intracortical evoked potentials of cats elicited by punctate visual stimuli in receptive field peripheries

Intracortical visual evoked potentials, related to stimulus eccentricity from receptive field center, were investigated as a possible measure of interaction among adjacent populations of cortical neurons. Displacement of the stimuli from field center resulted in (1) a progressive decline in amplitude of the primary potential and (2) an enhancement or development of longer latency (60-100 ms) 'secondary' potentials often not apparent with field center stimulation.