title: Task positive and default mode networks during a parametric working memory task in obstructive sleep apnea patients and healthy controls.
abstract: BACKGROUND
  Functional magnetic resonance imaging (fMRI) studies enable the investigation of neural correlates underlying behavioral performance. We investigate the working memory (WM) function of patients with untreated obstructive sleep apnea (OSA) from the view point of task positive and default mode networks (TPN and DMN, respectively) and compare the results to those of healthy controls (HC).
  
  
  METHODS
  A parametric fMRI experiment with 4 levels of visuospatial N-back task was used to investigate the pattern of cortical activation in 17 men with untreated moderate or severe OSA and 7 age-matched HC. Categorical and parametrical analysis of the data was performed. Multiple regression analysis of fMRI data of OSA patients was performed with AHI, nocturnal desaturation time, and BMI as covariates.
  
  
  RESULTS
  OSA patients demonstrate compensatory spatial recruitment of the TPN (maximal at 3-back) and of the DMN (maximal at 2-back). HC had a different patten of spatial recruitment and deactivation of the DMN at the maximal load of task (3-back). Nocturnal desaturation had significant positive correlation with BOLD signal in bilateral frontal, temporal, and occipital regions, and negative correlations in bilateral frontal and left parietal regions; whereas BMI showed only negative correlations with BOLD signal, predominantly in the PFC. AHI was positively correlated with BOLD signal in bilateral frontal regions.
  
  
  CONCLUSIONS
  Both TPN and DMN are affected in OSA patients, with nocturnal desaturation affecting both networks; whereas BMI appears to be the major negative factor influencing the TPN and has a significant negative correlation with behavioral performance.
authors.affiliation: Stanford University Sleep Clinic and Center for Human Sleep Research, Redwood City, CA, USA. opril@stanford.edu
authors.forename: Olga
authors.initials: O
authors.lastname: Prilipko
authors.forename: Nelly
authors.initials: N
authors.lastname: Huynh
authors.forename: Sophie
authors.initials: S
authors.lastname: Schwartz
authors.forename: Visasiri
authors.initials: V
authors.lastname: Tantrakul
authors.forename: Jee Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: Ana Rita
authors.initials: AR
authors.lastname: Peralta
authors.forename: Clete
authors.initials: C
authors.lastname: Kushida
authors.forename: Teresa
authors.initials: T
authors.lastname: Paiva
authors.forename: Christian
authors.initials: C
authors.lastname: Guilleminault
mesh_terms: D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D009778:Occipital Lobe / Q000502:physiology; D017286:Polysomnography; D012891:Sleep Apnea Syndromes / Q000503:physiopathology / Q000523:psychology*; D013647:Task Performance and Analysis; D013702:Temporal Lobe / Q000502:physiology