Enhancement of auditory sensory gating and stimulus-bound gamma band (40 Hz) oscillations in heavy tobacco smokers.

The effects of smoking tobacco on sensory gating, P50 and stimulus-bound gamma band oscillations (GBO; 32-48 Hz) in auditory evoked potentials were examined in a paired-tone paradigm (50 tone pip pairs; 70 dB, 1000 Hz). Thirteen cigarette (20+/day) smokers were tested after abstaining overnight and after smoking; 13 age-matched never-smokers were tested twice. Smokers exhibited chronic (rather than acute) effects in the frontal region: (1) larger P50 and GBO responses; (2) greater P50 and GBO sensory gating suppression. GBO analyses showed earlier sensory gating in smokers. These chronic effects of greater cortical activation and sensory gating may reflect persistent dopaminergic activation due to the inhibition of monoamine oxidase observed in smokers.