Relation between frontal 3-7 Hz MEG activity and the efficacy of ECT in major depression

The efficacy of electroconvulsive therapy (ECT) in major depression has been linked to the accentuation of postconvulsive prefrontal electroencephalography slow-wave activity. We investigated the change in slow-wave activity (0.5-7 Hz) using whole-scalp magnetoencephalographic (MEG) recordings. The 3-7 Hz (theta) activity increased in the right frontal and occipital regions during the course of treatment. After four treatments, the increase of the theta activity in the left frontal cortex correlated with the efficacy of the ECT treatment. Moreover, the change of the ratio of left and right frontal theta activity to occipital theta activity had a positive correlation with the therapeutic effect. These findings suggest that an efficient ECT treatment increases MEG theta activity in the frontal cortex.