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How do brain tumors alter functional
connectivity? A magnetoencephalography study
Bartolomei F, Bosma I, Klein M, Baayen JC,
Reijneveld JC, Postma TJ, Heimans JJ, van Dijk
BW, de Munck JC, de Jongh A, Cover KS, Stam
CJ
Department of Clinical Neurophysiology, Vrije Universiteit Medical
Center, Amsterdam, the Netherlands.
Objective. This study was undertaken to test the
hypothesis that brain tumors interfere with normal brain function by
disrupting functional connectivity of brain networks.
Methods. Functional
connectivity was assessed by computing the synchronization likelihood
in a broad band (0.5-60Hz) or in the gamma band (30-60Hz) between all
pairwise combinations of magnetoencephalography signals.
Magnetoencephalography recordings were made at rest in 17 brain tumor
patients and 15 healthy control subjects.
For a given threshold of synchronization likelihood values, graphs of
the suprathreshold connections between each magnetoencephalography
channel and the others channels were built.
Results. In some regions,
a variable number of channels without connectivity (missing connective
points) at this threshold was found.
The number of missing connective points was higher in patients with
brain tumors than in control subjects (p < 0.0001, broad and gamma
band) and was higher for left-sided than right-sided tumors (p =
0.008, broad band; p < 0.0001, gamma band).
Individual results analysis indicates that the majority of brain tumor
patients display several regions with missing connective point
alterations in the affected and in the contralateral hemisphere.
Interpretation. Our
findings suggest that brain tumors induce a loss of functional
connectivity that affects multiple brain regions, and that left side
brain tumors have the more severe consequences in this respect.
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