title: Establishing the dopamine dependency of human striatal signals during reward and punishment reversal learning.
abstract: Drugs that alter dopamine transmission have opposite effects on reward and punishment learning. These opposite effects have been suggested to depend on dopamine in the striatum. Here, we establish for the first time the neurochemical specificity of such drug effects, during reward and punishment learning in humans, by adopting a coadministration design. Participants (N = 22) were scanned on 4 occasions using functional magnetic resonance imaging, following intake of placebo, bromocriptine (dopamine-receptor agonist), sulpiride (dopamine-receptor antagonist), or a combination of both drugs. A reversal-learning task was employed, in which both unexpected rewards and punishments signaled reversals. Drug effects were stratified with baseline working memory to take into account individual variations in drug response. Sulpiride induced parallel span-dependent changes on striatal blood oxygen level-dependent (BOLD) signal during unexpected rewards and punishments. These drug effects were found to be partially dopamine-dependent, as they were blocked by coadministration with bromocriptine. In contrast, sulpiride elicited opposite effects on behavioral measures of reward and punishment learning. Moreover, sulpiride-induced increases in striatal BOLD signal during both outcomes were associated with behavioral improvement in reward versus punishment learning. These results provide a strong support for current theories, suggesting that drug effects on reward and punishment learning are mediated via striatal dopamine.
authors.affiliation: Donders Institute for Brain Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, the Netherlands and.
authors.forename: Marieke E
authors.initials: ME
authors.lastname: van der Schaaf
authors.forename: Martine R
authors.initials: MR
authors.lastname: van Schouwenburg
authors.forename: Dirk E M
authors.initials: DE
authors.lastname: Geurts
authors.forename: Arnt F A
authors.initials: AF
authors.lastname: Schellekens
authors.forename: Jan K
authors.initials: JK
authors.lastname: Buitelaar
authors.forename: Robbert Jan
authors.initials: RJ
authors.lastname: Verkes
authors.forename: Roshan
authors.initials: R
authors.lastname: Cools
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D001971:Bromocriptine / Q000494:pharmacology; D003342:Corpus Striatum / Q000098:blood supply / Q000187:drug effects*; D015259:Dopamine Agents / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation; D011678:Punishment / Q000523:psychology*; D012193:Reversal Learning / Q000187:drug effects* / Q000502:physiology*; D012201:Reward; D013469:Sulpiride / Q000494:pharmacology; D055815:Young Adult
chemical_list: D015259:Dopamine Agents; D001971:Bromocriptine; D013469:Sulpiride; D010100:Oxygen