Deviate N200 component of event-related potentials in shuchaku-seikaku, a premorbid personality of depression

Twenty-one healthy subjects with Shuchaku-Seikaku (SS), a premorbid personality of depression, and 44 control subjects were tested for event-related potentials using the auditory odd ball paradigm. A higher percent of the N200 component was evoked by frequent task-irrelevant stimuli in the Shuchaku-Seikaku (81.0%) subjects than in the controls (45.5%). The mean amplitudes in the 50-100 ms latency range for task-relevant rare stimuli were smaller; whereas, the amplitudes in the 100-200 ms range for task-irrelevant frequent stimuli and the amplitudes in the 200-260 ms range for both stimuli were larger (shifted to negative direction) in the SS subjects than in the controls. The evidence suggests that the fully automatic detection process, which is assumed to be correlated with mismatch negativity, is hypoactivated and that a contrarily controlled or conscious mismatch process, which may be N2b, is hyperactivated in SS.