title: Dopamine, affordance and active inference.
abstract: The role of dopamine in behaviour and decision-making is often cast in terms of reinforcement learning and optimal decision theory. Here, we present an alternative view that frames the physiology of dopamine in terms of Bayes-optimal behaviour. In this account, dopamine controls the precision or salience of (external or internal) cues that engender action. In other words, dopamine balances bottom-up sensory information and top-down prior beliefs when making hierarchical inferences (predictions) about cues that have affordance. In this paper, we focus on the consequences of changing tonic levels of dopamine firing using simulations of cued sequential movements. Crucially, the predictions driving movements are based upon a hierarchical generative model that infers the context in which movements are made. This means that we can confuse agents by changing the context (order) in which cues are presented. These simulations provide a (Bayes-optimal) model of contextual uncertainty and set switching that can be quantified in terms of behavioural and electrophysiological responses. Furthermore, one can simulate dopaminergic lesions (by changing the precision of prediction errors) to produce pathological behaviours that are reminiscent of those seen in neurological disorders such as Parkinson's disease. We use these simulations to demonstrate how a single functional role for dopamine at the synaptic level can manifest in different ways at the behavioural level.
authors.affiliation: The Wellcome Trust Centre for Neuroimaging, University College London, Queen Square, London, United Kingdom. k.friston@fil.ion.ucl.ac.uk
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Friston
authors.forename: Tamara
authors.initials: T
authors.lastname: Shiner
authors.forename: Thomas
authors.initials: T
authors.lastname: FitzGerald
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Galea
authors.forename: Rick
authors.initials: R
authors.lastname: Adams
authors.forename: Harriet
authors.initials: H
authors.lastname: Brown
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Dolan
authors.forename: Rosalyn
authors.initials: R
authors.lastname: Moran
authors.forename: Klaas Enno
authors.initials: KE
authors.lastname: Stephan
authors.forename: Sven
authors.initials: S
authors.lastname: Bestmann
mesh_terms: D001921:Brain / Q000502:physiology*; D003198:Computer Simulation; D003463:Cues; D003657:Decision Making / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism*; D006801:Humans; D008959:Models, Neurological; D009415:Nerve Net / Q000502:physiology*; D010470:Perceptual Masking / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D004298:Dopamine