Cortical effects of bromocriptine, a D-2 dopamine receptor agonist, in human subjects, revealed by fMRI.
Studies of human subjects performing cognitive tasks on and off dopaminergic drugs have suggested a specific role of dopamine in cognitive processes, particularly in working memory and prefrontal "executive" functions. However, the cortical effects of these drugs have been poorly understood. We used functional magnetic resonance imaging (fMRI) to examine both task-specific and general changes in cortical activity associated with bromocriptine, a selective agonist for D-2 dopamine receptors. Bromocriptine resulted in task-specific modulations of task-related activity in three cognitive tasks. Across tasks, the overall effect of the drug was to reduce task-related activity. We also observed drug effects on behavior that correlated with individual differences in memory span. We argue that bromocriptine may show both task-specific modulation and task-general inhibition of neural activity due to dopaminergic neurotransmission.
Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, USA. kimberg@mail.med.upenn.edu
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D000328:Adult; D001519:Behavior / Q000187:drug effects / Q000502:physiology; D001931:Brain Mapping; D001971:Bromocriptine / Q000008:administration & dosage*; D002421:Caudate Nucleus / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism; D003071:Cognition / Q000187:drug effects* / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000008:administration & dosage*; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D011597:Psychomotor Performance / Q000187:drug effects* / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000819:agonists* / Q000378:metabolism
D018491:Dopamine Agonists; D017448:Receptors, Dopamine D2; D001971:Bromocriptine; D004298:Dopamine