title: Effects of L-dopa during auditory instrumental learning in humans.
abstract: The dopaminergic neurotransmitter system is critically involved in promoting plasticity in auditory cortex. We combined functional magnetic resonance imaging (fMRI) and a pharmacological manipulation to investigate dopaminergic modulation of neural activity in auditory cortex during instrumental learning. Volunteers either received 100 mg L-dopa (Madopar) or placebo in an appetitive, differential instrumental conditioning paradigm, which involved learning that a specific category of frequency modulated tones predicts a monetary reward when fast responses were made in a subsequent reaction time task. The other category of frequency modulated tones was not related to a reward. Our behavioral data provides evidence that dopaminergic stimulation differentially impacts on the speed of instrumental responding in rewarded and unrewarded trials. L-dopa increased neural BOLD activity in left auditory cortex to tones in rewarded and unrewarded trials. This increase was related to plasma L-dopa levels and learning rate. Our data thus provides evidence for dopaminergic modulation of neural activity in auditory cortex, which occurs for both auditory stimuli related to a later reward and those not related to a reward.
authors.affiliation: Biological Psychology, Department of Psychology, Carl-von-Ossietzky University Oldenburg, Oldenburg, Germany. tina.weis@uni-oldenburg.de
authors.forename: Tina
authors.initials: T
authors.lastname: Weis
authors.forename: Sebastian
authors.initials: S
authors.lastname: Puschmann
authors.forename: Andre
authors.initials: A
authors.lastname: Brechmann
authors.forename: Christiane M
authors.initials: CM
authors.lastname: Thiel
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001307:Auditory Perception / Q000187:drug effects*; D001519:Behavior / Q000187:drug effects; D001931:Brain Mapping; D003216:Conditioning, Operant / Q000187:drug effects*; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D059032:Learning Curve; D007980:Levodopa / Q000008:administration & dosage / Q000494:pharmacology*; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008636:Mesencephalon / Q000187:drug effects / Q000502:physiology; D010100:Oxygen / Q000097:blood
chemical_list: D007980:Levodopa; D010100:Oxygen