title: Neural correlates of working memory performance in primary insomnia.
abstract: OBJECTIVE
  To examine neural correlates of working memory performance in patients with primary insomnia (PIs) compared with well-matched good sleepers (GSs).
  
  
  METHODS
  Twenty-five PIs and 25 GSs underwent functional MRI while performing an N-back working memory task.
  
  
  METHODS
  VA hospital sleep laboratory and University-based functional imaging center.
  
  
  METHODS
  25 PIs, 25 GSs.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  Although PIs did not differ from GSs in cognitive performance, PIs showed the expected differences from GSs in both self-reported and objective sleep measures. PIs, relative to GSs, showed reduced activation of task-related working memory regions. This manifested both as an overall reduction in activation of task-related regions and specifically as reduced modulation of right dorsolateral prefrontal cortex with increasing task difficulty. Similarly, PIs showed reduced modulation (i.e., reduced deactivation) of default mode regions with increasing task difficulty, relative to GSs. However, PIs showed intact performance.
  
  
  CONCLUSIONS
  These data establish a profile of abnormal neural function in primary insomnia, reflected both in reduced engagement of task-appropriate brain regions and an inability to modulate task-irrelevant (i.e., default mode) brain areas during working memory performance. These data have implications for better understanding the neuropathophysiology of the well established, yet little understood, discrepancy between ubiquitous subjective cognitive complaints in primary insomnia and the rarely found objective deficits during testing.
authors.affiliation: Psychology Service, VA San Diego Healthcare System, San Diego, CA 92161, USA. drummond@ucsd.edu
authors.forename: Sean P A
authors.initials: SP
authors.lastname: Drummond
authors.forename: Matthew
authors.initials: M
authors.lastname: Walker
authors.forename: Erin
authors.initials: E
authors.lastname: Almklov
authors.forename: Manuel
authors.initials: M
authors.lastname: Campos
authors.forename: Dane E
authors.initials: DE
authors.lastname: Anderson
authors.forename: Laura D
authors.initials: LD
authors.lastname: Straus
mesh_terms: D056044:Actigraphy; D000328:Adult; D001921:Brain / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009483:Neuropsychological Tests; D017286:Polysomnography; D007319:Sleep Initiation and Maintenance Disorders / Q000503:physiopathology*
keywords: Default mode; N-back; functional MRI; insomnia; sleep; working memory