Hemispheric imbalances in schizophrenia

Abstract

Evidence is presented of two syndromes in schizophrenia distinguished by opposite asymmetries in hemispheric activation. A florid syndrome is coincidental with left hemisphere overactivation and a non-florid syndrome with right hemispheric overactivation. In each case underactivation characterizes the opposite hemisphere. While this was first revealed by electrodermal lateral asymmetries, a review of the literature provides support from other measures of dynamic process asymmetries such as arousal and attention, and includes electrocortical activity in the form of EEG activity and evoked potentials (EP), the Hoffman reflex, lateral eye movements, auditory thresholds, dichotic listening, somatosensory extinction and handedness. A preliminary empirical test of the model involving a spectral analysis of EPs recorded from occipital and temporal placements was also confirmatory. While hemispheric imbalance may result from asymmetries in fixed structural processes the imbalance itself determines the form the psychosis follows which, due to the dynamic nature of the neuropsychological process, is presumably modifiable.