title: Default mode network abnormalities during state switching in attention deficit hyperactivity disorder.
abstract: BACKGROUND
  Individuals with attention deficit hyperactivity disorder (ADHD) display excess levels of default mode network (DMN) activity during goal-directed tasks, which are associated with attentional disturbances and performance decrements. One hypothesis is that this is due to attenuated down-regulation of this network during rest-to-task switching. A second related hypothesis is that it may be associated with right anterior insula (rAI) dysfunction - a region thought to control the actual state-switching process.
  
  
  METHODS
  These hypotheses were tested in the current fMRI study in which 19 adults with ADHD and 21 typically developing controls undertook a novel state-to-state switching paradigm. Advance cues signalled upcoming switches between rest and task periods and switch-related anticipatory modulation of DMN and rAI was measured. To examine whether rest-to-task switching impairments may be a specific example of a more general state regulation deficit, activity upon task-to-rest cues was also analysed.
  
  
  RESULTS
  Against our hypotheses, we found that the process of down-regulating the DMN when preparing to switch from rest to task was unimpaired in ADHD and that there was no switch-specific deficit in rAI modulation. However, individuals with ADHD showed difficulties up-regulating the DMN when switching from task to rest.
  
  
  CONCLUSIONS
  Rest-to-task DMN attenuation seems to be intact in adults with ADHD and thus appears unrelated to excess DMN activity observed during tasks. Instead, individuals with ADHD exhibit attenuated up-regulation of the DMN, hence suggesting disturbed re-initiation of a rest state.
authors.affiliation: Department of Experimental-Clinical and Health Psychology,Ghent University,Ghent,Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Sidlauskaite
authors.affiliation: Department of Experimental-Clinical and Health Psychology,Ghent University,Ghent,Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Sonuga-Barke
authors.affiliation: Department of Experimental-Clinical and Health Psychology,Ghent University,Ghent,Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Roeyers
authors.affiliation: Department of Experimental-Clinical and Health Psychology,Ghent University,Ghent,Belgium.
authors.forename: J R
authors.initials: JR
authors.lastname: Wiersema
mesh_terms: D000293:Adolescent; D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D003463:Cues; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012146:Rest / Q000502:physiology*; D013647:Task Performance and Analysis; D015854:Up-Regulation; D055815:Young Adult
keywords: Attention deficit hyperactivity disorder; default mode network; insula; state switching