Disordered functional connectivity in schizophrenia.

The first functional neuroimaging studies of schizophrenia, using single photon (SPET) and positron emission tomography (PET), led to the notion of abnormal 'hypofrontality' (Ingvar & Franzen, 1974). Although consistent with data linking schizophrenia with deficits in frontal function, the popularity of'hypofrontality' gradually faded as technically and methodologically more sophisticated studies failed to replicate the findings from which it arose (Gur & Gur, 1995). A more recent concept to emerge from neuroimaging research in schizophrenia, is that of disordered 'functional connectivity'. Normal functional connectivity is defined operationally as the 'temporal correlation between spatially remote neurophysiological events' (Friston el al. 1992).