Dopamine-mediated reinforcement learning signals in the striatum and ventromedial prefrontal cortex underlie value-based choices
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1
FMRIB Centre, University of Oxford, United Kingdom
The neurotransmitter dopamine (DA), in particular in the striatum, is crucially involved in reinforcement learning. However, many choice situations do not only require approaching an appetitive or avoiding an aversive stimulus. Rather, decisions may involve choice between several good (or alternatively several bad) options and selection of one stimulus is based on the relative values of the options. In my talk, I will present data from an fMRI study in which participants perform a reinforcement learning task under the influence of either a low dose of the D2 antagonist amisulpride (200 mg) or placebo. I will argue that dopaminergic antagonism not only affects encoding of reward prediction errors (PE) in the striatum, as has already been shown, but also amplifies the representation of expected value in the vmPFC. Behaviourally, amisulpride had no effect on initial reinforcement learning. In a later transfer phase in which decisions had to be made on the basis of previously learnt values (in the absence of an outcome), amisulpride selectively improved the ability to select the better of two highly rewarding options, without affecting decisions between two very poor options. Activity in the ventral caudate encoded a PE in the learning phase. In the transfer phase, activity in the vmPFC covaried with the available options’ learnt value on each trial. Both of these signals were predictive of subjects’s performance in the transfer phase, and both were enhanced under amisulpride. These data show that dopaminergic mechanisms a) enhance reinforcement learning signals in the striatum and b) amplify representations of learnt value in the vmFPC which are employed for reward-guided choices. Funding: DFG.
Keywords:
D2,
goal-directed behavior
Conference:
XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011.
Presentation Type:
Symposium: Oral Presentation
Topic:
Symposium 24: Adaptive, goal-directed behavior: prefrontal cortex and beyond
Citation:
Jocham
G
(2011). Dopamine-mediated reinforcement learning signals in the striatum and ventromedial prefrontal cortex underlie value-based choices.
Conference Abstract:
XI International Conference on Cognitive Neuroscience (ICON XI).
doi: 10.3389/conf.fnhum.2011.207.00603
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Received:
14 Nov 2011;
Published Online:
28 Nov 2011.
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Correspondence:
Dr. Gerhard Jocham, FMRIB Centre, University of Oxford, Oxford, United Kingdom, jocham@nf.mpg.de