title: A thalamocorticostriatal dopamine network for psychostimulant-enhanced human cognitive flexibility.
abstract: BACKGROUND
  Everyday life demands continuous flexibility in thought and behavior. We examined whether individual differences in dopamine function are related to variability in the effects of amphetamine on one aspect of flexibility: task switching.
  
  
  METHODS
  Forty healthy human participants performed a task-switching paradigm following placebo and oral amphetamine administration. [(18)F]fallypride was used to measure D2/D3 baseline receptor availability and amphetamine-stimulated dopamine release.
  
  
  RESULTS
  The majority of the participants showed amphetamine-induced benefits through reductions in switch costs. However, such benefits were variable. Individuals with higher baseline thalamic and cortical receptor availability and striatal dopamine release showed greater reductions in switch costs following amphetamine than individuals with lower levels. The relationship between dopamine receptors and stimulant-enhanced flexibility was partially mediated by striatal dopamine release.
  
  
  CONCLUSIONS
  These data indicate that the impact of the psychostimulant on cognitive flexibility is influenced by the status of dopamine within a thalamocorticostriatal network. Beyond demonstrating a link between this dopaminergic network and the enhancement in task switching, these neural measures accounted for unique variance in predicting the psychostimulant-induced cognitive enhancement. These results suggest that there may be measurable aspects of variability in the dopamine system that predispose certain individuals to benefit from and hence use psychostimulants for cognitive enhancement.
authors.affiliation: Department of Psychology, Vanderbilt University, Nashville, Tennessee; Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee 37240, USA. g.samanezlarkin@vanderbilt.edu
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Samanez-Larkin
authors.forename: Joshua W
authors.initials: JW
authors.lastname: Buckholtz
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Cowan
authors.forename: Neil D
authors.initials: ND
authors.lastname: Woodward
authors.forename: Rui
authors.initials: R
authors.lastname: Li
authors.forename: M Sib
authors.initials: MS
authors.lastname: Ansari
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Arrington
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Baldwin
authors.forename: Clarence E
authors.initials: CE
authors.lastname: Smith
authors.forename: Michael T
authors.initials: MT
authors.lastname: Treadway
authors.forename: Robert M
authors.initials: RM
authors.lastname: Kessler
authors.forename: David H
authors.initials: DH
authors.lastname: Zald
mesh_terms: D000223:Adaptation, Psychological / Q000187:drug effects*; D000293:Adolescent; D000328:Adult; D001549:Benzamides / Q000008:administration & dosage; D002540:Cerebral Cortex / Q000000981:diagnostic imaging; D003071:Cognition / Q000187:drug effects; D003342:Corpus Striatum / Q000000981:diagnostic imaging; D003913:Dextroamphetamine / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D009415:Nerve Net; D011759:Pyrrolidines / Q000008:administration & dosage; D011877:Radionuclide Imaging; D013788:Thalamus / Q000000981:diagnostic imaging; D055815:Young Adult
chemical_list: D001549:Benzamides; D018492:Dopamine Antagonists; C094948:N-((1-allyl-2-pyrrolidinyl)methyl)-5-(3-fluoropropyl)-2,3-dimethoxybenzamide; D011759:Pyrrolidines; D003913:Dextroamphetamine; D004298:Dopamine