Electrophysiological correlates of cognitive inhibition in college students with schizotypal traits

Abstract

Objective: We investigated cognitive inhibition in non-clinical individuals with schizotypal traits using event-related potentials. Methods: College students with psychometrically defined schizotypal traits (n = 16) and normal controls (n = 15) participated. The computerized Stroop task with three types of stimuli, i.e., congruent, incongruent, and neutral words, was used to measure cognitive inhibition. Results: The schizotypal-trait group committed significantly more errors in response to incongruent words than did the control group. The control group showed frontal negativity (FN) of significantly greater amplitude in response to incongruent than to congruent and neutral stimuli, whereas the schizotypal-trait group showed no significant difference in FN amplitude between incongruent and congruent/neutral stimuli at 300 - 400 ms poststimulus. A source localization analysis conducted in different waveforms for incongruent minus congruent conditions at 300-400 ms poststimulus showed reduced activation in the left cingulate cortex and in the middle/medial prefrontal cortex in the schizotypal-trait group compared with the control group. The two groups did not differ in the sustained potential amplitudes observed at 550-650 ms after stimulus-onset at parietal sites. Conclusions: These results suggest that individuals with schizotypal traits have difficulties in conflict detection and cognitive inhibition, possibly mediated by the cingulate cortex and prefrontal cortex.