title: EEG slow waves in traumatic brain injury: Convergent findings in mouse and man.
abstract: OBJECTIVE
  Evidence from previous studies suggests that greater sleep pressure, in the form of EEG-based slow waves, accumulates in specific brain regions that are more active during prior waking experience. We sought to quantify the number and coherence of EEG slow waves in subjects with mild traumatic brain injury (mTBI).
  
  
  METHODS
  We developed a method to automatically detect individual slow waves in each EEG channel, and validated this method using simulated EEG data. We then used this method to quantify EEG-based slow waves during sleep and wake states in both mouse and human subjects with mTBI. A modified coherence index that accounts for information from multiple channels was calculated as a measure of slow wave synchrony.
  
  
  RESULTS
  Brain-injured mice showed significantly higher theta:alpha amplitude ratios and significantly more slow waves during spontaneous wakefulness and during prolonged sleep deprivation, compared to sham-injured control mice. Human subjects with mTBI showed significantly higher theta:beta amplitude ratios and significantly more EEG slow waves while awake compared to age-matched control subjects. We then quantified the global coherence index of slow waves across several EEG channels in human subjects. Individuals with mTBI showed significantly less EEG global coherence compared to control subjects while awake, but not during sleep. EEG global coherence was significantly correlated with severity of post-concussive symptoms (as assessed by the Neurobehavioral Symptom Inventory scale).
  
  
  CONCLUSIONS
  Taken together, our data from both mouse and human studies suggest that EEG slow wave quantity and the global coherence index of slow waves may represent a sensitive marker for the diagnosis and prognosis of mTBI and post-concussive symptoms.
authors.affiliation: Brain Rehabilitation Research Center, North Florida/South Georgia Veterans Affairs Medical Center, Gainesville, FL.
authors.forename: Mo
authors.initials: M
authors.lastname: Modarres
authors.affiliation: Research Service, Veterans Affairs Portland Health Care System, Portland OR; Department of Physics, Portland State University, Portland, OR.
authors.forename: Nicholas N
authors.initials: NN
authors.lastname: Kuzma
authors.affiliation: Department of Mental Health and Behavioral Sciences, James A. Haley Veterans' Hospital, Tampa, FL.
authors.forename: Tracy
authors.initials: T
authors.lastname: Kretzmer
authors.affiliation: Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Allan I
authors.initials: AI
authors.lastname: Pack
authors.affiliation: Research Service, Veterans Affairs Portland Health Care System, Portland OR; Sleep Disorders Clinic, Division of Hospital and Specialty Medicine, Veterans Affairs Portland Health Care System, Portland OR; Departments of Medicine, Neurology and Behavioral Neuroscience, and Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR.
authors.forename: Miranda M
authors.initials: MM
authors.lastname: Lim
keywords: EEG; Traumatic brain injury; coherence; sleep; slow waves; translational