title: Increasing task difficulty facilitates the cerebral compensatory response to total sleep deprivation.
abstract: OBJECTIVE
  To test the role of task difficulty in the cerebral compensatory response after total sleep deprivation (TSD).
  
  
  METHODS
  Subjects performed a modified version of Baddeley's logical reasoning task while undergoing functional magnetic resonance imaging twice: once after normal sleep and once following 35 hours of TSD. The task was modified to parametrically manipulate task difficulty.
  
  
  METHODS
  Inpatient General Clinical Research Center and outpatient functional magnetic resonance imaging center.
  
  
  METHODS
  16 young adults (7 women; mean age, 27.6 +/- 6.1 years; education, 15.4 +/- 1.8 years) were included in the final analyses.
  
  
  METHODS
  None.
  
  
  RESULTS
  Behaviorally, subjects performed the same after TSD as while well rested. Neuroimaging data revealed a linear increase in cerebral response with a linear increase in task demands in several brain regions after normal sleep. Even stronger linear responses were found after TSD in several brain regions, including bilateral inferior parietal lobes, bilateral temporal cortex, and left inferior and dorsolateral prefrontal cortex.
  
  
  CONCLUSIONS
  Task difficulty facilitates the cerebral compensatory response observed following TSD. Compensation manifests as both new regions that did not show significant responses to task demands in the well-rested condition, as well as stronger responses within regions typically underlying task performance. The possible significance of these 2 types of responses should be explored further, as should the importance of the parietal lobes for cognitive performance after TSD.
authors.affiliation: Department of Psychiatry, University of California San Diego, 92161, USA. drummond@ucsd.edu
authors.forename: Sean P A
authors.initials: SP
authors.lastname: Drummond
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Brown
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Salamat
authors.forename: J Christian
authors.initials: JC
authors.lastname: Gillin
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology / Q000098:blood supply / Q000503:physiopathology*; D003071:Cognition / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012892:Sleep Deprivation / Q000503:physiopathology*