Schizophrenia: A disease of heteromodal association cortex?

There is considerable evidence of disturbances of multiple brain areas in schizophrenia. The clinical features and findings from pathologic and neuro-imaging studies suggest primary involvement of a system of parallel distributed networks within the neocortex-the phylogenetically recent heteromodal association cortex (HASC). There is evidence that HASC is a family of higher-order parallel distributed networks of circuits, mediating complex representationally guided behaviors. We argue that HASC regions are especially involved in schizophrenia. Lesions of HASC in the disease are likely to be neurodevelopmental in origin (as evidenced by such examples as reversed planum temporale asymmetry) which have been identified by magnetic resonance imaging as specific regions of disproportionately reduced local gray matter volumes, and by neuropathologic examination as cellular migration disruptions. We believe the hypothesis of preferential heteromodal cortical abnormalities has heuristic value, and briefly indicate how it opens new avenues for investigating this debilitating condition.