The effect of smoking on pain-related evoked potentials.

The effects of human tobacco smoking and nicotine on pain-related brain activities were investigated. EEG responses evoked by a painful laser beam (laser evoked potentials; LEPs), and the plasma nicotine concentration (PNC) were measured. There were two sessions, one after smoking (Smoking session), and the other in no smoking (Control session). Subjective ratings of pain perception were also measured using the visual analog scale (VAS). Two major components, N2 and P2 of LEPs, were recorded. The amplitude of P2 was significantly smaller in the Smoking session than in the Control session. A significant negative correlation was found between PNC and the amplitude of N2 as well as P2. The results were consistent with the hypothesis that smoking and/or nicotine have an antinociceptive effect, which supports most non-human studies and some human studies. Smoking of a single tobacco cigarette did not show a subjectively perceivable extent of reduction in the intensity of evoked pain.