title: Atypical brain activation during simple & complex levels of processing in adult ADHD: an fMRI study.
abstract: OBJECTIVE
  Executive dysfunction in ADHD is well supported. However, recent studies suggest that more fundamental impairments may be contributing. We assessed brain function in adults with ADHD during simple and complex forms of processing.
  
  
  METHODS
  We used functional magnetic resonance imaging with forward and backward digit spans to investigate number repetitions and complex working memory function. If pathology is limited to higher cognitive operations, group differences should be confined to the backward condition.
  
  
  RESULTS
  During the forward digit span, ADHD participants exhibited greater activation of LH linguistic processing areas and increased activation of right frontal and parietal cortices. During the backward digit span, they exhibited greater activation of LH linguistic processing areas and failed to activate bilateral parietal regions important for the complex executive operations.
  
  
  CONCLUSIONS
  Abnormal brain function among adult ADHD participants was not limited to complex executive functions. Abnormal processing of numeric stimuli was indicated during both simple and complex cognitive operations.
authors.affiliation: Division of Child and Adolescent Psychiatry, Neuropsychiatric Institute and David Geffen School of Medicine at UCLA, Los Angeles, CA, USA. sig@ucla.edu
authors.forename: T Sigi
authors.initials: TS
authors.lastname: Hale
authors.forename: Susan
authors.initials: S
authors.lastname: Bookheimer
authors.forename: James J
authors.initials: JJ
authors.lastname: McGough
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Phillips
authors.forename: James T
authors.initials: JT
authors.lastname: McCracken
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology*; D001307:Auditory Perception / Q000502:physiology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D004292:Dominance, Cerebral / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D006179:Gyrus Cinguli / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009415:Nerve Net / Q000503:physiopathology; D010296:Parietal Lobe / Q000503:physiopathology; D017397:Prefrontal Cortex / Q000503:physiopathology; D011340:Problem Solving / Q000502:physiology*