Endogenous event-related potentials in obsessive character.

Fifteen healthy subjects with obsessive character (OC) and 15 control subjects were tested for endogenous event-related potentials using the auditory odd ball paradigm. A difference was found in the peak amplitude of the P200 component in response to both stimuli; the subjects with OC had smaller amplitudes than the controls, and the mean amplitude for the 120 to 200 ms latency range was smaller (negative shift) for the OC subjects. In the OC subjects, NA appears to be markedly induced to both rare and frequent stimuli; moreover, the OC subjects may show excessive reactions to selective attention as well as to the process of pattern recognition.