title: Methylphenidate enhances executive function and optimizes prefrontal function in both health and cocaine addiction.
abstract: Previous studies have suggested dopamine to be involved in error monitoring/processing, possibly through impact on reinforcement learning. The current study tested whether methylphenidate (MPH), an indirect dopamine agonist, modulates brain and behavioral responses to error, and whether such modulation is more pronounced in cocaine-addicted individuals, in whom dopamine neurotransmission is disrupted. After receiving oral MPH (20 mg) or placebo (counterbalanced), 15 healthy human volunteers and 16 cocaine-addicted individuals completed a task of executive function (the Stroop color word) during functional magnetic resonance imaging (fMRI). During MPH, despite not showing differences on percent accuracy and reaction time, all subjects committed fewer total errors and slowed down more after committing errors, suggestive of more careful responding. In parallel, during MPH all subjects showed reduced dorsal anterior cingulate cortex response to the fMRI contrast error>correct. In the cocaine subjects only, MPH also reduced error>correct activity in the dorsolateral prefrontal cortex (controls instead showed lower error>correct response in this region during placebo). Taken together, MPH modulated dopaminergically innervated prefrontal cortical areas involved in error-related processing, and such modulation was accentuated in the cocaine subjects. These results are consistent with a dopaminergic contribution to error-related processing during a cognitive control task.
authors.affiliation: Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Moeller
authors.forename: Jean
authors.initials: J
authors.lastname: Honorio
authors.forename: Dardo
authors.initials: D
authors.lastname: Tomasi
authors.forename: Muhammad A
authors.initials: MA
authors.lastname: Parvaz
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Woicik
authors.forename: Nora D
authors.initials: ND
authors.lastname: Volkow
authors.forename: Rita Z
authors.initials: RZ
authors.lastname: Goldstein
mesh_terms: D000328:Adult; D001245:Association Learning / Q000187:drug effects; D000697:Central Nervous System Stimulants / Q000494:pharmacology / Q000627:therapeutic use*; D019970:Cocaine-Related Disorders / Q000150:complications*; D003072:Cognition Disorders / Q000188:drug therapy* / Q000209:etiology / Q000473:pathology; D056344:Executive Function / Q000187:drug effects*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology / Q000627:therapeutic use*; D008875:Middle Aged; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D017397:Prefrontal Cortex / Q000098:blood supply / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate; D010100:Oxygen