Functional connectivity in mild cognitive impairment during a memory task

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Publication Details

Subtitle: Implications for the disconnection hypothesis
Author list: Pereda E
Publisher: IOS Press
Publication year: 2010
Volume number: 22
Issue number: 1
Start page: 183
End page: 193
Number of pages: 11
ISSN: 1387-2877
Languages: English-Great Britain (EN-GB)


Mild cognitive impairment (MCI) has been considered an intermediate
state between healthy aging and dementia. The early damage in anatomical
connectivity and progressive loss of synapses that characterize early
Alzheimer's disease suggest that MCI could also be a disconnection
syndrome. Here, we compare the degree of synchronization of brain
signals recorded with magnetoencephalography from patients (22) with MCI
with that of healthy controls (19) during a memory task.
Synchronization Likelihood, an index based on the theory of nonlinear
dynamical systems, was used to measure functional connectivity. During
the memory task patients showed higher interhemispheric synchronization
than healthy controls between left and right -anterior temporo-frontal
regions (in all studied frequency bands) and in posterior regions in the
γ band. On the other hand, the connectivity pattern from healthy
controls indicated two clusters of higher synchronization, one among
left temporal sensors and another one among central channels. Both of
them were found in all frequency bands. In the γ band, controls showed
higher Synchronization Likelihood values than MCI patients between
central-posterior and frontal-posterior channels and a high
synchronization in posterior regions. The inter-hemispheric increased
synchronization values could reflect a compensatory mechanism for the
lack of efficiency of the memory networks in MCI patients. Therefore,
these connectivity profiles support only partially the idea of MCI as a
disconnection syndrome, as patients showed increased long distance
inter-hemispheric connections but a decrease in antero-posterior
functional connectivity.


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Last updated on 2019-13-08 at 00:45