BILATERAL ELECTRODERMAL ACTIVITY AND CEREBRAL MECHANISMS IN SYNDROMES OF SCHIZOPHRENIA AND THE SCHIZOTYPAL PERSONALITY

Bilateral electrodermal measurement was among the first to investigate abnormalities of lateralization in schizophrenia, and recent classification of non-institutionalized patients by lateral asymmetry has delineated positive and negative syndromes associated with opposite states of hemispheric balance. The neuropsychology of the symptoms is consistent with higher left- than right-hemispheric activity in the positive syndrome, and higher right- than left-hemispheric activity in the negative syndrome, evidence which in turn is consistent with current theory about hemispheric influences on electrodermal responses. As all patients had Schneiderian symptoms in common this provided a three-syndrome model, a model having affinities with contemporary reports of three-factor solutions in factor analyses of clinical ratings. All approaches describe two positive syndromes and one negative syndrome. The same model applied to the schizotypal personality has produced a three-factor solution having a strong bearing on the three schizophrenia syndromes, together with evidence of imbalances in functional lateralization that are consistent with the schizophrenia model. It is proposed that the controversy surrounding the orienting and habituation anomalies in schizotypal personality, which include reduced activity, augmented activity, and irregular habituation, may be elucidated by examining relationships with the three-syndrome model and through bilateral measurement. However, provision must be made for distinctions between processes of fixed structure and dynamic function, a critical requirement in view of the relations between electrodermal reactivity and orienting to the dynamic processes of arousal, attention and anxiety. The central nervous system underpinnings of electrodermal responsiveness in schizophrenia, notably the responder-non-responder distinction, is beginning to be elucidated through neuropsychological testing and brain imaging techniques. Research is warranted to explore an integration between the syndromes which evolved from bilateral measurement, and the responder-non-responder classification which arose from considerations of limbic dysfunction.