title: Reproducibility of changes in behaviour and fMRI activation associated with sleep deprivation in a working memory task.
abstract: OBJECTIVE
  Although the stability of inter-individual differences in vulnerability to sleep deprivation has been shown behaviourally, the neural basis for these differences has yet to be uncovered. In this study, we assessed the reproducibility of fMRI activation and performance on a working memory task before and after 24 hours of sleep deprivation (SD).
  
  
  METHODS
  All volunteers underwent 2 sessions (pairs of fMRI scans) at rested wakefulness (RW) and after SD.
  
  
  METHODS
  19 healthy, right-handed subjects (mean age = 21.37 +/- 1.54 years).
  
  
  RESULTS
  Brain activation was highly correlated across sessions in a frontoparietal network previously implicated in working memory function. The magnitude of decline in this activation after SD was preserved in bilateral parietal regions. Among several behavioural metrics investigated, the most robust marker of vulnerability to SD was the change in the intra-individual variability of reaction times. This was shown to be both stable over time and correlated with the drop in left parietal activation from RW to SD in both experimental sessions.
  
  
  CONCLUSIONS
  Because of its reproducibility, the modulation of parietal activation may provide a good physiological marker of vulnerability to SD.
authors.affiliation: Cognitive Neuroscience Laboratory, Duke-NUS Graduate Medical School, Singapore.
authors.forename: Julian
authors.initials: J
authors.lastname: Lim
authors.forename: Wei-Chieh
authors.initials: WC
authors.lastname: Choo
authors.forename: Michael W L
authors.initials: MW
authors.lastname: Chee
mesh_terms: D000328:Adult; D001143:Arousal / Q000502:physiology; D001931:Brain Mapping; D003463:Cues; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006179:Gyrus Cinguli / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009415:Nerve Net / Q000503:physiopathology; D010296:Parietal Lobe / Q000503:physiopathology*; D010364:Pattern Recognition, Visual / Q000502:physiology; D017397:Prefrontal Cortex / Q000503:physiopathology; D011340:Problem Solving / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012892:Sleep Deprivation / Q000503:physiopathology*