THE NEUROPSYCHOLOGY OF SCHIZOPHRENIA

A model is proposed for integrating the neural and cognitive aspects of the positive symptoms of acute schizophrenia using evidence from: postmortem neuropathology and neurochemistry, clinical and preclinical studies of dopaminergic neurotransmission, anatomical connections between the limbic system and the basal ganglia, attentional and other cognitive abnormalities underlying the positive symptoms of schizophrenia, specific animal models of some of these abnormalities, and previous attempts to model the cognitive functions of the spetohippocampal system and the motor functions of the basal ganglia. Anatomically, the model emphasises the projections from the septohippocampal system, via the subiculum and the amygdala to nucleus accumbens and their interaction with the ascending dopaminergic projection to the accumbens. Psychologically, the model emphasizes a failure in schizophrenia to integrate stored memories of past regularieties of perceptual input with ongoing motor programs in the control of current perception. A number of recent experiments that offer support for the model are fully described, including anatomical studies of limbic-striatal connections, studies in the rat of the effects of damage to these connections and of the effects of amphetamine and neuroleptics on the partial reinforcement extinction effect, latent inhibition and the Kamin blocking effect, and studies of the latter two phenomena in acuate and chronic schizophrenics.