Abnormal neural integration related to cognition in schizophrenia

A striking feature of schizophrenia is the diversity of the phenomenology both within and between patients. This diversity can be contrasted with the well‐circumscribed and stable deficits seen in classic neuropsychological syndromes. The argument will be advanced that the classic lesion model, based on the notion of a segregated deficit, is inappropriate in schizophrenia. Instead the idea will be developed that a more appropriate model is one derived from concepts of neural integration across large‐scale brain networks. Empirical data derived from positron emission tomography (PET) within our laboratory that provide support fur this suggestion will be presented. One critical observation from these data is a disruption of prefrontal‐temporal interactions. under a variety of cognitive activation paradigms, in both chronic medicated and acute unmediated schizophrenic patients. Furthermore, these data indicate that both regional and interregional neuronal function, including prefrontal‐temporal interactions, can be significantly modulated by a neurochetnical perturbation of ascending dopaminergic systems. The latter observations suggest that the deficit of abnormal cortico‐cortical interactions are to some extent modifiable by neuromociulatory neurotransmitter systems.