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Human brain networks in physiological aging: a graph theoretical analysis of cortical connectivity from EEG data.

Authors
  • Vecchio, Fabrizio1
  • Miraglia, Francesca1
  • Bramanti, Placido2
  • Rossini, Paolo Maria3
  • 1 Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy. , (Italy)
  • 2 IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy. , (Italy)
  • 3 Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy Institute of Neurology, Catholic University, Rome, Italy. , (Italy)
Type
Published Article
Journal
Journal of Alzheimer s Disease
Publisher
IOS Press
Publication Date
Jan 01, 2014
Volume
41
Issue
4
Pages
1239–1249
Identifiers
DOI: 10.3233/JAD-140090
PMID: 24820018
Source
Medline
Keywords
License
Unknown

Abstract

Modern analysis of electroencephalographic (EEG) rhythms provides information on dynamic brain connectivity. To test the hypothesis that aging processes modulate the brain connectivity network, EEG recording was conducted on 113 healthy volunteers. They were divided into three groups in accordance with their ages: 36 Young (15-45 years), 46 Adult (50-70 years), and 31 Elderly (>70 years). To evaluate the stability of the investigated parameters, a subgroup of 10 subjects underwent a second EEG recording two weeks later. Graph theory functions were applied to the undirected and weighted networks obtained by the lagged linear coherence evaluated by eLORETA on cortical sources. EEG frequency bands of interest were: delta (2-4 Hz), theta (4-8 Hz), alpha1 (8-10.5 Hz), alpha2 (10.5-13 Hz), beta1 (13-20 Hz), beta2 (20-30 Hz), and gamma (30-40 Hz). The spectral connectivity analysis of cortical sources showed that the normalized Characteristic Path Length (λ) presented the pattern Young > Adult>Elderly in the higher alpha band. Elderly also showed a greater increase in delta and theta bands than Young. The correlation between age and λ showed that higher ages corresponded to higher λ in delta and theta and lower in the alpha2 band; this pattern reflects the age-related modulation of higher (alpha) and decreased (delta) connectivity. The Normalized Clustering coefficient (γ) and small-world network modeling (σ) showed non-significant age-modulation. Evidence from the present study suggests that graph theory can aid in the analysis of connectivity patterns estimated from EEG and can facilitate the study of the physiological and pathological brain aging features of functional connectivity networks.

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