Fine structure of the auditory M100 in schizophrenia and schizoaffective disorder

Background: Several studies have demonstrated anomalous asymmetry of the 10 0-msec latency auditory-evoked field (M100) in schizophrenia Recent evidenc e suggests this may be a compound component however Our study examines the localization of two M100 subcomponents in patients with schizophrenia and s chizoaffective disorder. Methods: Magnetoencephalographic recordings of auditory-evoked fields were obtained for 14 subjects with schizophrenia, 12 with schizoaffective disord er and 23 control subjects. Two M100 subcomponents were identified and loca lized in each hemisphere. Results: Both patient groups exhibited different lateralization compared wi th control subjects, with the second subcomponent tending to be less latera lized Conclusions: The second subcomponent may be the major contributor to previo usly reported laterality differences. Future studies might benefit by separ ating M100 subcomponents so that specific functions could be addressed. (C) 2000 Society of Biological Psychiatry.