A Janusian perspective on the nature, development and structure of schizophrenia and schizotypy

A personal review is presented of the functional basis of activation, withdrawal and unreality, individual differences in schizophrenia that Venables et al. pioneered. Activated and withdrawn syndromes were delineated from the totality of symptoms by classifying unmedicated patients on the basis of lateral asymmetries in electrodermal responses. A neuropsychological syndrome translation led to a syndrome hemispheric imbalance model supported by a literature review disclosing widespread cortical and infracortical involvement extending to motoneurone excitability, with validation from tests of learning, memory and evoked responses including the P300. It is contended that the centrality of arousal, the extensive substrate and the evidence of asymmetry modification with recovery and treatment all implicate specific and nonspecific thalamo-cortical systems whose uncoupling may lead to dysfunction of input, cognition and to unreality symptoms (found inconsistently related to asymmetry). The three syndromes have developmental associations including immune competence, ventricular changes and lateral asymmetry, putative regressive neuronal changes in connectivity and electrocortical measures of connectivity, as well as sensory gating and anomalies of P50 suppression and habituation. Replication of the syndromal structure in psychometric schizotypy indicates that syndrome expression is based on the premorbid personality, compatible with evidence of early determinants of the approach/withdrawal balance in social encounters. Functional considerations for the nature of schizophrenia support neurophysiological approaches to treatment such as neurofeedback.