Functions of the dopaminergic innervation of the nucleus accumbens

Abstract

Two different current views hold that the mesolimbic dopaminergic projection to the nucleus accumbens mediates (1) the behavioral effects of reward or positive incentive motivation and (2) the cognitive functions that go awry in acute schizophrenia. These two views are difficult to integrate with each other. The former view fits better with the established role that the nucleus accumbens plays in the motor programming circuitry of the basal ganglia; but it fits poorly with evidence that dopamine release is provoked in the nucleus accumbens not only by rewarding, but also by aversive, stimuli. We review evidence, especially from experiments using the prepulse and latent inhibition paradigms, consistent with a role for the mesolimbic dopaminergic pathway in the cognitive dysfunctions of schizophrenia. We also propose a new model for the functions of this pathway which draws on recent evidence that the nucleus accumbens has outputs to perceptual as well as motor systems. The model is able in principle to account for the data sets that support both major current views of the functions of the mesolimbic dopaminergic system. It has not yet received support, however, from direct experimental tests.