Early and late auditory sensory gating: moderating influences from schizotypal personality, tobacco smoking status, and acute smoking.

Early (P50) and late (P200) auditory sensory gating were assessed in low and high schizotypal personality groups using Raine's Schizotypal Personality Questionnaire. We also assessed the impact of smoking as it relates to low and high schizotypal personalities. Low and high schizoptypal personality groups were divided into subgroups of participants who either smoked or did not smoke tobacco cigarettes. Participants were 39 (18 men) right-handed undergraduates. Using a paired-tone paradigm (40 pairs, 70 dB, 1000 Hz), smokers were tested while abstaining from smoking, and 5 min after smoking. Non-smokers were tested similarly without smoking. Midline and hemispheric sites were evaluated at frontal (F3/Fz/F4), fronto-central (FC3/FCz/FC4), central (C3/Cz/C4), centro-parietal (CP3/CPz/CP4), and parietal (P3/Pz/P4) regions. P50 sensory gating was better at midline sites than left/right hemispheric sites, whereas there was no difference in activation with respect to location for P200 sensory gating. Cz had better P50 sensory gating than other midline regions, whereas Fz, FCz and Cz had better P200 sensory gating than CPz and Pz. Hemispheric comparisons were made. At the central region for non-smokers, high schizotypys showed poorer P50 sensory gating than low schizotypys. Among low schizotypys, smokers showed poorer P50 sensory gating than non-smokers at the fronto-central and central regions smokers showed better P200 sensory gating than non-smokers at the central region. Smoking had no acute impact on either early (P50) or late (P200) sensory gating. Our data support the notion that early sensory gating and late sensory gating represent different sensory gating mechanisms with respect to low and high schizotypy personalities. Individual differences in early and late sensory gating need further investigation.