Delusions, superstitious conditioning and chaotic dopamine neurodynamics

Excessive mesolimbic dopaminergic neurotransmission is closely related to t he psychotic symptoms of schizophrenia. A mathematical model of dopamine ne uron firing rates, developed by King and others, suggests a mechanism by wh ich excessive dopaminergic transmission could produce psychotic symptoms, e specially delusions. In this model, firing rates varied chaotically when th e efficacy of dopaminergic transmission was enhanced. Such noncontingent ch anges in firing rates in mesolimbic reward pathways could produce delusions by distorting thinking in the same way that non-contingent reinforcement p roduces superstitious conditioning. Though difficult to test in humans, the hypothesis is testable as an explan ation for a common animal model of psychosis - amphetamine stereotypy in ra ts. The hypothesis predicts that: (1) amphetamine will cause chaotic firing rates in mesolimbic dopamine neurons; (2) non-contingent brain stimulation reward will produce stereotypy; (3) noncontingent microdialysis of dopamin e into reward areas will produce stereotypy; and (4) dopamine antagonists w ill block all three effects.