title: A functional magnetic resonance imaging study of the effects of pergolide, a dopamine receptor agonist, on component processes of working memory.
abstract: Working memory is an important cognitive process dependent on a network of prefrontal and posterior cortical regions. In this study we tested the effects of the mixed D1-D2 dopamine receptor agonist pergolide on component processes of human working memory using functional magnetic resonance imaging (fMRI). An event-related trial design allowed separation of the effects on encoding, maintenance, and retrieval processes. Subjects were tested with spatial and object memoranda to investigate modality-specific effects of dopaminergic stimulation. We also measured baseline working memory capacity as previous studies have shown that effects of dopamine agonists vary with working memory span. Pergolide improved reaction time for high-span subjects and impaired reaction time for low-span subjects. This span-dependent change in behavior was accompanied by span-dependent changes in delay-related activity in the premotor cortex. We also found evidence for modality-specific effects of pergolide only during the response period. Pergolide increased activity for spatial memoranda and decreased activity for object memoranda in task-related regions including the prefrontal and parietal cortices.
authors.affiliation: Henry H. Wheeler Jr. Brain Imaging Center, Helen Wills Neuroscience Institute and Department of Psychology, University of California, Berkeley, 132 Barker Hall, Berkeley, CA 94720-1650, USA. sebgibbs@berkeley.edu
authors.forename: S E B
authors.initials: SE
authors.lastname: Gibbs
authors.forename: M
authors.initials: M
authors.lastname: D'Esposito
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects / Q000502:physiology*; D009483:Neuropsychological Tests; D015588:Observer Variation; D010296:Parietal Lobe / Q000187:drug effects / Q000378:metabolism; D010364:Pattern Recognition, Visual / Q000187:drug effects / Q000502:physiology; D010479:Pergolide / Q000494:pharmacology*; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism*; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D011954:Receptors, Dopamine / Q000187:drug effects / Q000378:metabolism*; D013028:Space Perception / Q000187:drug effects / Q000502:physiology
chemical_list: D018491:Dopamine Agonists; D011954:Receptors, Dopamine; D010479:Pergolide; D004298:Dopamine