Source Distribution of Neuromagnetic Slow Waves and MEG-Delta Activity in Schizophrenic Patients

Abstract

Background: Schizophrenic patients exhibit more activity<br />in the electroencephalographic delta and theta frequency<br />range than do control subjects. Using magnetic source<br />imaging (MSI) our study aimed to explore this phenomenon<br />in the magnetoencephalogram (MEG), the distribution<br />of its sources, and associations between symptom<br />profiles and sources of low-frequency activity in the brain.<br />Methods: Whole-head MEG recordings were obtained<br />from 28 schizophrenic patients and 20 healthy control<br />subjects during a resting condition. The generators of the<br />focal magnetic slow waves were located employing a<br />single moving dipole model. Distributed or multiple delta<br />and theta sources were captured by the minimum norm<br />estimate.<br />Results: Both localization procedures showed slow wave<br />activity to be enhanced in schizophrenic patients compared<br />with control subjects. Focal slow wave activity<br />differed most between groups in frontotemporal and in<br />posterior regions. Slow wave activity was associated with<br />symptom characteristics in that positive symptoms varied<br />with frontal delta and theta activity.<br />Conclusions: Results indicate that activity in low-frequency<br />bands in schizophrenic patients exceeds the activity<br />of control subjects in distinct areas, and that this focal<br />clustering of neuromagnetic slow waves may be related to psychopathologic characteristics.