title: EEG characteristics in "eyes-open" versus "eyes-closed" conditions: Small-world network architecture in healthy aging and age-related brain degeneration.
abstract: OBJECTIVE
  Applying graph theory, we investigated how cortical sources small worldness (SW) of resting EEG in eyes-closed/open (EC/EO) differs in amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD) subjects with respect to normal elderly (Nold).
  
  
  METHODS
  EEG was recorded in 30 Nold, 30 aMCI, and 30 AD during EC and EO. Undirected and weighted cortical brain network was built to evaluate graph core measures. eLORETA lagged linear connectivity was used to weight the network.
  
  
  RESULTS
  In Nold, in EO condition, the brain network is characterized by more SW (higher SW) in alpha bands and less SW (lower SW) in beta2 and gamma bands. In aMCI, SW has the same trend, except for delta and theta bands where the network shows less small worldness. AD shows a similar trend of Nold, but with less fluctuations between EO/EC conditions. Furthermore, in both conditions, aMCI SW architecture presents midway properties between AD and Nold. At low frequencies (delta e theta bands) in EC, aMCI group presents network's architecture similar to Nold, while in EO aMCI, SW is superimposable to AD ones.
  
  
  CONCLUSIONS
  In resting state condition, aMCI small-world architecture presents midway topological properties between AD subjects and healthy controls, confirming the hypothesis that aMCI is an intermediate step along the disease progression.
  
  
  CONCLUSIONS
  We proposed the application of graph theory to EEG in reactivity to EO in order to find a marker of diagnosis that - in association with other techniques of neuroimaging - could be sensitive to the progression of MCI or conversion into AD.
authors.affiliation: Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy. Electronic address: fra.miraglia@gmail.com.
authors.forename: Francesca
authors.initials: F
authors.lastname: Miraglia
authors.affiliation: Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Vecchio
authors.affiliation: IRCCS Centro NeurolesiBonino-Pulejo, Messina, Italy.
authors.forename: Placido
authors.initials: P
authors.lastname: Bramanti
authors.affiliation: Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy; Institute of Neurology, Catholic University, Rome, Italy.
authors.forename: Paolo Maria
authors.initials: PM
authors.lastname: Rossini
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000473:pathology / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009415:Nerve Net / Q000473:pathology / Q000502:physiology*; D012146:Rest / Q000502:physiology*
keywords: EEG; Functional connectivity; Graph theory; Resting state; Small-world networks; eLORETA