Elsevier

NeuroImage: Clinical

Volume 20, 2018, Pages 564-571
NeuroImage: Clinical

Brain functional networks become more connected as amyotrophic lateral sclerosis progresses: a source level magnetoencephalographic study

https://doi.org/10.1016/j.nicl.2018.08.001Get rights and content
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Highlights

  • Brain networks grow more connected as amyotrophic lateral sclerosis progresses.

  • Such changes affect the brain globally, they are not focal.

  • The topology of brain networks reaches a suboptimal configuration as amyotrophic lateral sclerosis progresses.

  • Brain networks modifications involve multiple frequency bands.

  • Brain networks become more scale-free and more disassortative as disease progresses.

Abstract

This study hypothesizes that the brain shows hyper connectedness as amyotrophic lateral sclerosis (ALS) progresses. 54 patients (classified as “early stage” or “advanced stage”) and 25 controls underwent magnetoencephalography and MRI recordings. The activity of the brain areas was reconstructed, and the synchronization between them was estimated in the classical frequency bands using the phase lag index. Brain topological metrics such as the leaf fraction (number of nodes with degree of 1), the degree divergence (a measure of the scale-freeness) and the degree correlation (a measure of disassortativity) were estimated. Betweenness centrality was used to estimate the centrality of the brain areas.

In all frequency bands, it was evident that, the more advanced the disease, the more connected, scale-free and disassortative the brain networks. No differences were evident in specific brain areas. Such modified brain topology is sub-optimal as compared to controls. Within this framework, our study shows that brain networks become more connected according to disease staging in ALS patients.

Keywords

Motor neuron disease
Connectivity
Magnetic source imaging
Neuroimaging biomarker

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1

These authors contributed equally to this paper.