title: Traumatic brain injury alters the functional brain network mediating working memory.
abstract: OBJECTIVE
  Investigation of the impact of traumatic brain injury (TBI) on the functional brain network that mediates working memory function.
  
  
  METHODS
  Functional magnetic resonance imaging (fMRI) during an n-back working memory task in nine chronic-stage patients with TBI and nine age-matched healthy controls. In addition to classical analyses investigating regional activity, the authors examined functional connectivity of the brain regions critical to working memory performance using psychophysiological interaction (PPI) analyses.
  
  
  RESULTS
  Patients with TBI made a greater percentage of errors than controls at high working memory load conditions. The fMRI data showed that the activation of the left inferior parietal gyrus (LIPG) was significantly reduced, whereas the activation of the right inferior frontal gyrus (RIFG) was significantly increased in patients compared with controls. Task performance accuracy was significantly associated with the activation of the LIPG in controls and the activation of the RIFG in patients. PPI analyses on fMRI data further suggested that the functional connectivity between the RIFG and LIPG was compromised in patients.
  
  
  CONCLUSIONS
  The abnormal functional connectivity between LIPG and RIFG may underlie the observed working memory deficits and abnormal brain activation pattern in patients.
authors.affiliation: Division of Anaesthesia, University of Cambridge, Addenbrooke’s Hospital, UK.
authors.forename: Maki
authors.initials: M
authors.lastname: Kasahara
authors.forename: David K
authors.initials: DK
authors.lastname: Menon
authors.forename: Claire H
authors.initials: CH
authors.lastname: Salmond
authors.forename: Joanne G
authors.initials: JG
authors.lastname: Outtrim
authors.forename: Joana V Taylor
authors.initials: JV
authors.lastname: Tavares
authors.forename: T Adrian
authors.initials: TA
authors.lastname: Carpenter
authors.forename: John D
authors.initials: JD
authors.lastname: Pickard
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Sahakian
authors.forename: Emmanuel A
authors.initials: EA
authors.lastname: Stamatakis
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001930:Brain Injuries / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D005625:Frontal Lobe / Q000293:injuries / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000293:injuries / Q000503:physiopathology*; D013647:Task Performance and Analysis; D055815:Young Adult