Electroconvulsive therapy and lateralized affective systems.

The neurophysiological systems subtending generalized seizures (activated by ECT) and temporal-limbic seizures are described as well as the interactions existing between the two seizure systems. There are correlations between schizophrenia and the limbic seizure system on the one hand and the manic-depressive or bipolar syndromes and the generalized seizure system on the other which are theoretically related to the different (although overlapping) neural substrates underlying the two major syndromes of psychosis. Evidence is reviewed that indicates that in ECT-responsive depression (with both bilateral and unilateral nondominant ECT) the modus operandi hinges on right-hemispheric neural events. Neurophysiological, neurological, and acoustic threshold evidence is discussed: all of which emphasizes the importance of the nondominant hemisphere in the genesis of endogenous depressions and in their treatment with convulsive therapies. In addition, studies showing that psychotropic agents with specific antidepressant effects produce asymmetric activation of the right hemisphere (EEG) are related to the above issues.