title: Response inhibition and reward anticipation in medication-naïve adults with attention-deficit/hyperactivity disorder: a within-subject case-control neuroimaging study.
abstract: BACKGROUND
  Previous research suggests that ADHD patients are characterized by both reduced activity in the inferior frontal gyrus (IFG) during response inhibition tasks (such as the Go-NoGo task), and reduced activity in the ventral striatum during reward anticipation tasks (such as the Monetary-Incentive-Delay [MID] task). However, no prior research has applied either of these paradigms in medication-naïve adults with ADHD, nor have these been implemented in an intrasubject manner.
  
  
  METHODS
  The sample consisted of 19 medication-naïve adults with ADHD and 19 control subjects. Main group analyses were based on individually defined regions of interest: the IFG and the VStr for the Go-NoGo and the MID task respectively. In addition, we analyzed the correlation between the two measures, as well as between these measures and the clinical symptoms of ADHD.
  
  
  RESULTS
  We observed reduced bilateral VStr activity in adults with ADHD during reward anticipation. No differences were detected in IFG activation on the Go-NoGo paradigm. Correlation analyses suggest that the two tasks are independent at a neural level, but are related behaviorally in terms of the variability of the performance reaction time. Activity in the bilateral VStr but not in the IFG was associated negatively with symptoms of hyperactivity/impulsivity.
  
  
  CONCLUSIONS
  Results underline the implication of the reward system in ADHD adult pathophysiology and suggest that frontal abnormalities during response inhibition performance may not be such a pivotal aspect of the phenotype in adulthood. In addition, our findings point toward response variability as a core feature of the disorder.
authors.affiliation: Departament de Psiquiatria i Medicina Legal, Universitat Autònoma de Barcelona, Bellaterra, Spain. susannacarmona@gmail.com
authors.forename: Susana
authors.initials: S
authors.lastname: Carmona
authors.forename: Elseline
authors.initials: E
authors.lastname: Hoekzema
authors.forename: J Antoni
authors.initials: JA
authors.lastname: Ramos-Quiroga
authors.forename: Vanesa
authors.initials: V
authors.lastname: Richarte
authors.forename: Clara
authors.initials: C
authors.lastname: Canals
authors.forename: Rosa
authors.initials: R
authors.lastname: Bosch
authors.forename: Mariana
authors.initials: M
authors.lastname: Rovira
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Soliva
authors.forename: Antonio
authors.initials: A
authors.lastname: Bulbena
authors.forename: Adolf
authors.initials: A
authors.lastname: Tobeña
authors.forename: Miguel
authors.initials: M
authors.lastname: Casas
authors.forename: Oscar
authors.initials: O
authors.lastname: Vilarroya
mesh_terms: D000328:Adult; D059031:Anticipation, Psychological / Q000502:physiology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007175:Impulsive Behavior / Q000503:physiopathology; D007266:Inhibition, Psychological; D008279:Magnetic Resonance Imaging; D008297:Male; D012201:Reward