title: Striatum in stimulus-response learning via feedback and in decision making.
abstract: Cognitive deficits are recognized in Parkinson's disease. Understanding cognitive functions mediated by the striatum can clarify some of these impairments and inform treatment strategies. The dorsal striatum, a region impaired in Parkinson's disease, has been implicated in stimulus-response learning. However, most investigations combine acquisition of associations between stimuli, responses, or outcomes (i.e., learning) and expression of learning through response selection and decision enactment, confounding these separate processes. Using neuroimaging, we provide evidence that dorsal striatum does not mediate stimulus-response learning from feedback but rather underlies decision making once associations between stimuli and responses are learned. In the experiment, 11 males and 5 females (mean age 22) learned to associate abstract images to specific button-press responses through feedback in Session 1. In Session 2, they were asked to provide responses learned in Session 1. Feedback was omitted, precluding further feedback-based learning in this session. Using functional magnetic resonance imaging, dorsal striatum activation in healthy young participants was observed at the time of response selection and not during feedback, when greatest learning presumably occurs. Moreover, dorsal striatum activity increased across the duration of Session 1, peaking after most associations were well learned, and was significant during Session 2 where no feedback was provided, and therefore no feedback-based learning occurred. Preferential ventral striatum activity occurred during feedback and was maximal early in Session 1. Taken together, the results suggest that the ventral striatum underlies learning associations between stimuli and responses via feedback whereas the dorsal striatum mediates enacting decisions.
authors.affiliation: Brain and Mind Institute, University of Western Ontario, London, Ontario N6A 5B7, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5C1, Canada.
authors.forename: Nole M
authors.initials: NM
authors.lastname: Hiebert
authors.affiliation: Brain and Mind Institute, University of Western Ontario, London, Ontario N6A 5B7, Canada; Department of Psychology, University of Western Ontario, London, Ontario N6A 5C2, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Vo
authors.affiliation: Faculty of Medicine, Imperial College, London SW7 2AZ, United Kingdom.
authors.forename: Adam
authors.initials: A
authors.lastname: Hampshire
authors.affiliation: Brain and Mind Institute, University of Western Ontario, London, Ontario N6A 5B7, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5C1, Canada; Department of Psychology, University of Western Ontario, London, Ontario N6A 5C2, Canada.
authors.forename: Adrian M
authors.initials: AM
authors.lastname: Owen
authors.affiliation: Brain and Mind Institute, University of Western Ontario, London, Ontario N6A 5B7, Canada.
authors.forename: Ken N
authors.initials: KN
authors.lastname: Seergobin
authors.affiliation: Brain and Mind Institute, University of Western Ontario, London, Ontario N6A 5B7, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5C1, Canada; Department of Psychology, University of Western Ontario, London, Ontario N6A 5C2, Canada; Department of Clinical Neurological Sciences, University of Western Ontario, London, Ontario N6A 5A5, Canada. Electronic address: penny.macdonald@gmail.com.
authors.forename: Penny A
authors.initials: PA
authors.lastname: MacDonald
mesh_terms: D000328:Adult; D001245:Association Learning / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D003657:Decision Making / Q000502:physiology*; D030141:Feedback, Psychological / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D017072:Neostriatum / Q000502:physiology*; D066328:Ventral Striatum / Q000502:physiology*; D055815:Young Adult
keywords: Decision making; Functional MRI; Parkinson's disease; Stimulus–response learning; Striatum