An integrative psychophysiological approach to brain hemisphere functions in schizophrenia.

The present paper proposes a new psychophysiological approach to the genesis of positive and negative schizophrenic symptoms. According to this approach, the initial factor in schizophrenic disorders is a functional insufficiency of the right hemisphere which can be determined by early emotional experience in combination with subtle brain damage. This functional insufficiency causes (a) the inability to grasp and select information before its realization; and (b) the inability to produce a polysemantic context which is crucial for creativity, psychological defense, and the restoration of search activity, all of which determine psychophysiological adaptation to the environment. Right hemisphere insufficiency causes left hemisphere hyperactivity as an ineffective attempt to compensate for this functional deficiency. As a result, normal search activity is replaced by artificial search activity which is represented by "positive" symptoms, and which uses the predisposition of the left hemisphere's catecholamine system for its increased activity. The suggestion is made that cognitive impairment in schizophrenia (the inability to use appropriate previous information in relation to current perceptual input) is related to the competition between information processing which requires left hemisphere activity, and the formation of positive symptoms, also based on left hemisphere activity.