title: Altered neural activation in ornithine transcarbamylase deficiency during executive cognition: an fMRI study.
abstract: BACKGROUND
  Ornithine transcarbamylase deficiency (OTCD) is an X-linked urea cycle disorder characterized by hyperammonemia resulting in white matter injury and impairments in working memory and executive cognition.
  
  
  OBJECTIVE
  To test for differences in BOLD signal activation between subjects with OTCD and healthy controls during a working memory task.
  
  
  METHODS
  Nineteen subjects with OTCD and 21 healthy controls participated in a case-control, IRB-approved study at Georgetown University Medical Center.
  
  
  METHODS
  An N-back working memory task was performed in a block design using 3T functional magnetic resonance imaging.
  
  
  RESULTS
  In subjects with OTCD we observed increased BOLD signal in the right dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC) relative to healthy age matched controls.
  
  
  CONCLUSIONS
  Increased neuronal activation in OTCD subjects despite equivalent task performance points to sub-optimal activation of the working memory network in these subjects, most likely reflecting damage caused by hyperammonemic events. These increases directly relate to our previous finding of reduced frontal white matter integrity in the superior extents of the corpus callosum; key hemispheric connections for these areas. Future studies using higher cognitive load are required to further characterize these effects.
authors: Department of Neurology, Children's National Medical Center, Washington, DC 20010, USA. agropman@childrensnational.org
authors: Andrea L
authors: AL
authors: Gropman
authors: Kyle
authors: K
authors: Shattuck
authors: Morgan J
authors: MJ
authors: Prust
authors: Rebecca R
authors: RR
authors: Seltzer
authors: Andrew L
authors: AL
authors: Breeden
authors: Ayichew
authors: A
authors: Hailu
authors: Amanda
authors: A
authors: Rigas
authors: Rehan
authors: R
authors: Hussain
authors: John
authors: J
authors: VanMeter
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000098:blood supply*; D003071:Cognition / Q000502:physiology*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology; D009483:Neuropsychological Tests; D020163:Ornithine Carbamoyltransferase Deficiency Disease / Q000473:pathology* / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood
chemical_list: D010100:Oxygen