Event-related potential correlates of impaired attention in schizophrenic children

Electrophysiological correlates of focused attention were studied in 13 schizophrenic and 19 age- and gender-matched children. Subjects performed a version of the Continuous Performance Task (CPT) in which a target was designated as any digit from 0 through 9 occurring on two successive stimulus presentations. Signal digits were surrounded by distractor digits which varied in position, value, and number. Event-related potentials (ERPs) elicited by each stimulus of a target pair were recorded from midline and homologous parietal, temporal, and occipital electrode placements. Schizophrenic children made significantly more errors of omission and commission than normal children. The amplitude and time course of the intertrial CNV was the same for both groups. There was a circumscribed amplitude asymmetry, left smaller than right, for the P1/N1 and P2 measures which was greater in normal than in schizophrenic children. The P3 component was significantly larger to the second stimulus of the target pair than to the first for both groups, and larger for the normal than the schizophrenic children to both stimuli.