VEPs Generated by High Rates Pattern Reversal Stimulation

The effect of high modulation rate on pattern reversal visual evoked potentials (VEP) has not been well explored and no general agreement has been reached. Regan (1978) found that patterned VEPs occurred only at low temporal frequencies up to approximately 30 reversals per second (r/s) i.e 15 Hz. After that, the VEPs fall off sharply as frequency increases. By contrast, Tyler et al. (1980) found VEP responses, with signal-to-noise ratios of about 2:1, up to 90 r/s i.e 45 Hz. Moreover, it is recognized that unpatterned flicker stimuli over 60 Hz still elicited VEPs.