Delusions, superstitious conditioning and chaotic dopamine neurodynamics.
Excessive mesolimbic dopaminergic neurotransmission is closely related to the psychotic symptoms of schizophrenia. A mathematical model of dopamine neuron firing rates, developed by King and others, suggests a mechanism by which excessive dopaminergic transmission could produce psychotic symptoms, especially delusions. In this model, firing rates varied chaotically when the efficacy of dopaminergic transmission was enhanced. Such non-contingent changes in firing rates in mesolimbic reward pathways could produce delusions by distorting thinking in the same way that non-contingent reinforcement produces superstitious conditioning. Though difficult to test in humans, the hypothesis is testable as an explanation for a common animal model of psychosis--amphetamine stereotypy in rats. 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) non-contingent microdialysis of dopamine into reward areas will produce stereotypy; and (4) dopamine antagonists will block all three effects.
Shaner
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West Los Angeles VA Medical Center, CA 90073, USA. AShaner@UCLA.edu
D000661:Amphetamine / Q000633:toxicity; D000818:Animals; D003213:Conditioning, Psychological / Q000502:physiology; D003702:Delusions / Q000503:physiopathology*; D004195:Disease Models, Animal; D004298:Dopamine / Q000502:physiology*; D006801:Humans; D008959:Models, Neurological; D017711:Nonlinear Dynamics; D051381:Rats; D012559:Schizophrenia / Q000503:physiopathology; D012565:Schizophrenic Psychology; D013239:Stereotyped Behavior / Q000502:physiology; D013483:Superstitions / Q000523:psychology; D009435:Synaptic Transmission / Q000502:physiology
D000661:Amphetamine; D004298:Dopamine