Average responses evoked by moving grating pattern in the upper, central and lower visual field

Detectable visual evoked potentials were obtained in man by stimulation in the peripheral visual field with a 0.4 cycle/deg vertical grating pattern of 5 degrees arc subtense which moved twice per second horizontally at 415 degrees/sec through an amplitude of 8 degrees arc. These moving grating stimuli were presented to 10 normal subjects, centered 15 degrees above, or centered around, or centered 15 degrees below a fixation mark. The mean latencies (+/- S.D.) of the positive component of the potential evoked by stimuli to the central and 15 degrees eccentricity lower visual field were 114 +/- 17 msec and 104 +/- 20 msec, respectively, while latencies for 15 degrees eccentricity upper visual field stimuli were significantly (p less than 0.001) later with 148 +/- 20 msec.