title: Atypical coupling between posterior regions of the default mode network in attention-deficit/hyperactivity disorder: a pharmaco-magnetoencephalography study.
abstract: BACKGROUND
  Dysfunction in the default mode network (DMN), a group of cortical areas more active during the resting state, has been linked to attentional deficits and symptoms associated with attention-deficit/hyperactivity disorder (ADHD). Prior imaging studies have shown decreased functional connectivity between DMN nodes in patients with ADHD, primarily between anterior and posterior regions. Using magnetoencephalography (MEG), we evaluated phase coherence (i.e., functional connectivity) among regions of the DMN in healthy controls and adults with ADHD before and after stimulant therapy.
  
  
  METHODS
  We obtained a resting-state MEG recording for all participants. Magnetoencephalography data were transformed into a ~30 node regional source model using inverse spatial filtering, including regions corresponding to the DMN. We computed the zero-lag phase coherence between these regions pairwise for 5 distinct frequency bands, and we assessed group and medication effects.
  
  
  RESULTS
  Twelve adults with and 13 without ADHD participated in our study. Functional connectivity was stronger between particular node pairs and showed frequency-specific effects. Unmedicated patients showed reduced phase locking between posterior cingulate/precuneus regions (PCC) and right inferior parietal cortices (RIPL), and between medial prefrontal regions (MPFC) and the left inferior parietal region (LIPL) and the PCC. Unmedicated patients had increased phase locking between the RIPL and LIPL regions compared with controls. Administration of stimulants improved phase locking abnormalities along the MPFC-PCC and LIPL-RIPL pathways in patients with ADHD.
  
  
  CONCLUSIONS
  Modest sample size and lack of duration of patient treatment history may limit the generalizability of our findings.
  
  
  CONCLUSIONS
  Adults with ADHD exhibit hyper- and hypoconnectivity between regions of the DMN during rest, which were suppressed after stimulant medication administration.
authors.affiliation: Department of Psychiatry, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Franzen
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Heinrichs-Graham
authors.forename: Matthew L
authors.initials: ML
authors.lastname: White
authors.forename: Martin W
authors.initials: MW
authors.lastname: Wetzel
authors.forename: Nichole L
authors.initials: NL
authors.lastname: Knott
authors.forename: Tony W
authors.initials: TW
authors.lastname: Wilson
mesh_terms: D000328:Adult; D000662:Amphetamines / Q000494:pharmacology / Q000627:therapeutic use; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy / Q000503:physiopathology*; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000187:drug effects / Q000503:physiopathology*; D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000503:physiopathology; D012146:Rest / Q000502:physiology
chemical_list: D000662:Amphetamines; C449521:SLI381