Fine structure of the auditory M100 in schizophrenia and schizoaffective disorder

Background: Several studies have demonstrated anomalous asymmetry of the 100-msec latency auditory-evoked field (M100) in schizophrenia. Recent evidence suggests this may be a compound component, however. Our study examines the localization of two M100 subcomponents in patients with schizophrenia and schizoaffective disorder. Methods: Magnetoencephalographic recordings of auditory-evoked fields were obtained for 14 subjects with schizophrenia, 12 with schizoaffective disorder, and 23 control subjects. Two M100 subcomponents were identified and localized in each hemisphere. Results: Both patient groups exhibited different lateralization compared with control subjects, with the second subcomponent tending to be less lateralized. Conclusions: The second subcomponent may be the major contributor to previously reported laterality differences. Future studies might benefit by separating M100 subcomponents so that specific functions could be addressed.