Analysis of Electroencephalographic Dynamic Functional Connectivity in Alzheimer’s Disease
The aim of this study was to characterize the dynamic functional connectivity of resting-state electroencephalographic (EEG) activity in Alzheimer’s disease (AD). The magnitude squared coherence (MSCOH) of 50 patients with dementia due to AD and 28 cognitively healthy controls was computed. MSCOH was estimated in epochs of 60 s subdivided in overlapping windows of different lengths (1, 2, 3, 5 and 10 s; 50% overlap). The effect of epoch length was tested on MSCOH and it was found that MSCOH stabilized at a window length of 3 s. We tested whether the MSCOH fluctuations observed reflected actual changes in functional connectivity by means of surrogate data testing, with the standard deviation of MSCOH chosen as the test statistic. The results showed that the variability of the measure could be due to dynamic functional connectivity. Furthermore, a significant reduction in the dynamic MSCOH connectivity of AD patients compared to controls was found in the delta (0–4 Hz) and beta-1 (13–30 Hz) bands. This indicated that AD patients show lesser variation in neural connectivity during resting state. Finally, a correlation between relative power and standard deviation was found, suggesting that an increase/peak in power spectrum could be a pre-requisite for dynamic functional connectivity in a specific frequency band.
KeywordsAlzheimer’s disease Dynamic functional connectivity Electroencephalogram Neural dynamics Coherence Relative power
This study has been partially funded by projects TEC2014-53196-R of ‘Ministerio de Economía y Competitividad’ and FEDER, the project ‘Análisis y correlación entre el genoma completo y la actividad cerebral para la ayuda en el diagnóstico de la enfermedad de Alzheimer’ (Inter-regional cooperation program VA Spain-Portugal POCTEP 2014–2020) of the European Commission and FEDER, and project VA037U16 of the ‘Junta de Castilla y León and FEDER. P. Núñez and S. J. Ruiz are in receipt of predoctoral grants co-financed by the ‘Junta de Castilla y León’ and ESF.
Conflict of Interest
There are no conflicts of interest that could influence this research work.
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