Spontaneous, slow and fast magnetoencephalographic activity in patients with schizophrenia.

A 2* 37 channel biomagnetic system (Magnes II) was used to record spontaneous magnetic activity for the frequency ranges 2-6 Hz and 12.5-30 Hz in 30 patients with schizophrenia (23 men and 17 women) and 30 healthy volunteers in both hemispheres during a resting condition. The dipole localization was calculated by the dipole density plot (DDP) method, which is a spatial averaging in order to decrease the influence of the nonfocal activity. The quantified DDP results were superimposed to T2-weighted MR-images of each patient's head as isocontour lines. To superimpose the MEG results to 3-D MRI data, the scanned head data set was fitted to the reconstructed MRI head shape using a surface fit programme developed by our department. The absolute dipole values were correlated with the psychopathological findings and the cumulative neuroleptic dosage for each patient. The group of patients with schizophrenia differed overall from the healthy subjects in the elevation of absolute dipole values measured in both hemispheres. For the region of slow dipole activity (2-6 Hz), a high correlation was found between the intensity of dipole concentration and productive psychotic symptoms (PANSS, P1-P7). Dipole localization (for both frequency ranges) showed a concentration effect (DCE) in the temporoparietal region in patients with schizophrenia.