Rate of stimulus repetition changes evoked potential amplitude: dental and auditory modalities compared.

Vertex evoked potentials (40--500 ms) elicited by painful dental stimulation were compared with those elicited by innocuous auditory stimuli across three rates of stimulus repetition: one second, four seconds, and eight seconds. In both modalities peak amplitude of the major waveform components increased linearly over log rate as stimulus repetition was slowed, and latency of the latest positive component was increased. No changes in subjective stimulus intensity across rate of repetition were reported. These observations demonstrate that the normally close relationship between subjective pain report and EP amplitude is not variant, and they suggest that the development of EP methodology in human pain research should proceed conservatively.