Somatosensory evoked potentials (EPs) to stimuli ranging from barely perceptible to painful were recorded in 153 normal adults. Reliability of amplitude and amplitude/intensity slopes were demonstrated in 29 individuals tested twice, two or more weeks apart. In randomized, double-blind placebo controlled trials, both aspirin and morphine significantly diminished N120 component at high stimulus intensities. Age, sex and pharmacological effects paralleled those found with psychophysical techniques in part I of this study.
