title: Disturbed functional brain networks and neurocognitive function in low-grade glioma patients: a graph theoretical analysis of resting-state MEG.
abstract: BACKGROUND
  To understand neurophysiological mechanisms underlying cognitive dysfunction in low-grade glioma (LGG) patients by evaluating the spatial structure of 'resting-state' brain networks with graph theory.
  
  
  METHODS
  Standardized tests measuring 6 neurocognitive domains were administered in 17 LGG patients and 17 healthy controls. Magnetoencephalography (MEG) recordings were conducted during eyes-closed 'resting state'. The phase lag index (PLI) was computed in seven frequency bands to assess functional connectivity between brain areas. Spatial patterns were characterized with graph theoretical measures such as clustering coefficient (local connectivity), path length (global integration), network small world-ness (ratio of clustering coefficient/path length) and degree correlation (the extent to which connected nodes have similar degrees).
  
  
  RESULTS
  Compared to healthy controls, patients performed poorer on psychomotor functioning, attention, information processing, and working memory. Patients displayed higher short- and long-distance synchronization and clustering coefficient in the theta band, whereas a lower clustering coefficient and small world-ness were observed in the beta band. A lower degree correlation was found in the upper gamma band. LGG patients with higher clustering coefficient, longer path length, and lower degree correlations in delta and lower alpha band were characterized by poorer neurocognitive performance.
  
  
  CONCLUSIONS
  LGG patients display higher short- and long-distance synchronization within the theta band. Network analysis revealed changes (in particularly the theta, beta, and upper gamma band) suggesting disturbed network architecture. Moreover, correlations between network characteristics and neurocognitive performance were found, Widespread changes in the strength and spatial organization of brain networks may be responsible for cognitive dysfunction in glioma patients.
authors.affiliation: Department of Neurology, VU University Medical Center, Amsterdam, the Netherlands. i.bosma@vumc.nl.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Bosma
authors.forename: Jaap C
authors.initials: JC
authors.lastname: Reijneveld
authors.forename: Martin
authors.initials: M
authors.lastname: Klein
authors.forename: Linda
authors.initials: L
authors.lastname: Douw
authors.forename: Bob W
authors.initials: BW
authors.lastname: van Dijk
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Heimans
authors.forename: Cornelis J
authors.initials: CJ
authors.lastname: Stam
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