Tobacco smoking and cortical evoked potentials: an opposite effect on auditory and visual systems.

1. Auditory and visual evoked potentials produced by five intensities of tones and light flashes were recorded in twelve young men who were habitual smokers. 2. The subjects attended the laboratory on four occasions. Two recordings were made on each of the last three of these visits. They were made (i) before and after smoking, (ii) without smoking, (iii) before and after smoking after 12 h abstinence from smoking. 3. Smoking was associated with increases in the amplitudes of the components V-VI, VI-VII in the visual system and a decrease in the amplitude of N2P2 in the auditory system. Abstinence from smoking produced effects in the opposite direction. 4. These findings are consistent with the possibility that smoking has different and perhaps opposite effects on the visual and auditory system. 5. The findings may be helpful in re-evaluating some of the apparently conflicting reports on the effects of smoking on perceptual processes.