Elsevier

NeuroImage: Clinical

Volume 2, 2013, Pages 414-423
NeuroImage: Clinical

Disturbed resting state EEG synchronization in bipolar disorder: A graph-theoretic analysis

https://doi.org/10.1016/j.nicl.2013.03.007Get rights and content
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Highlights

  • Global synchronization of BD patients was reduced in the alpha-band at resting.

  • De-synchronized connectivity was localized in fronto-centro-parietal connections.

  • Global topology of BD had decreased network clustering and increased path length.

  • BD showed the less efficient network processing.

  • Network characteristics of BD patients were associated with depression severity.

Abstract

Disruption of functional connectivity may be a key feature of bipolar disorder (BD) which reflects disturbances of synchronization and oscillations within brain networks. We investigated whether the resting electroencephalogram (EEG) in patients with BD showed altered synchronization or network properties. Resting-state EEG was recorded in 57 BD type-I patients and 87 healthy control subjects. Functional connectivity between pairs of EEG channels was measured using synchronization likelihood (SL) for 5 frequency bands (δ, θ, α, β, and γ). Graph-theoretic analysis was applied to SL over the electrode array to assess network properties. BD patients showed a decrease of mean synchronization in the alpha band, and the decreases were greatest in fronto-central and centro-parietal connections. In addition, the clustering coefficient and global efficiency were decreased in BD patients, whereas the characteristic path length increased. We also found that the normalized characteristic path length and small-worldness were significantly correlated with depression scores in BD patients. These results suggest that BD patients show impaired neural synchronization at rest and a disruption of resting-state functional connectivity.

Abbreviations

b
node betweenness centrality
BD
bipolar disorder
C
clustering coefficients
DSM-IV
diagnostic and statistical manual of mental disorders, the 4th-edition
DTI
diffusion tensor imaging (image)
EEG
electroencephalogram
EOG
electrooculogram
Eg
global efficiency
El
local efficiency
FA
fractional anisotropy
FDR
false discovery rate
fMRI
functional magnetic resonance imaging
GABA
gamma-amino butyric acid
L
characteristic path length
MADRS
Montgomery–Asberg Depression Rating Scale
MEG
magnetoencephalogram
MRI
magnetic resonance imaging
NBS
network-based statistics
NC
normal healthy control
PLI
phase lag index
s
node strength
SCID
Structured Clinical Interview for DSM Disorders
SL
synchronization likelihood
WASI
Wechsler Abbreviated Scale of Intelligence
WM
white matter
YMRS
Young Mania Rating Scale
γ
normalized clustering coefficients
λ
normalized characteristic path length
σ
small-worldness

Keywords

Bipolar disorder
Electroencephalogram
Synchronization likelihood
Graph theory
Functional connectivity
Resting state

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