Unraveling the Mysteries of Cognitive-Impaired Alzheimer’s through Brain Connectivity and Complexity

Published on June 6, 2022

Imagine the brain as a bustling city, with its numerous pathways and connections. In a groundbreaking study, scientists delved into the intricate dynamics of the brain by investigating the interplay between functional connectivity and complexity. Using a mathematical model, they analyzed how different regions of the brain communicate and discovered fascinating insights about mild cognitive-impaired Alzheimer’s disease (MCI-AD). Real electroencephalogram (EEG) signals from patients with MCI-AD showed reduced functional connectivity and complexity in specific brain regions. This finding was further validated through simulation studies with lesion-induced control groups. The simulations revealed that decreased connectivity led to a decrease in EEG complexity. The study highlights a direct relationship between functional connectivity and complexity in MCI-AD, providing new avenues for understanding this complex neurological condition.

BackgroundFunctional connectivity and complexity analysis has been discretely studied to understand intricate brain dynamics. The current study investigates the interplay between functional connectivity and complexity using the Kuramoto mean-field model.MethodFunctional connectivity matrices are estimated using the weighted phase lag index and complexity measures through popularly used complexity estimators such as Lempel-Ziv complexity (LZC), Higuchi’s fractal dimension (HFD), and fluctuation-based dispersion entropy (FDispEn). Complexity measures are estimated on real and simulated electroencephalogram (EEG) signals of patients with mild cognitive-impaired Alzheimer’s disease (MCI-AD) and controls. Complexity measures are further applied to simulated signals generated from lesion-induced connectivity matrix and studied its impact. It is a novel attempt to study the relation between functional connectivity and complexity using a neurocomputational model.ResultsReal EEG signals from patients with MCI-AD exhibited reduced functional connectivity and complexity in anterior and central regions. A simulation study has also displayed significantly reduced regional complexity in the patient group with respect to control. A similar reduction in complexity was further evident in simulation studies with lesion-induced control groups compared with non-lesion-induced control groups.ConclusionTaken together, simulation studies demonstrate a positive influence of reduced connectivity in the model imparting a reduced complexity in the EEG signal. The study revealed the presence of a direct relation between functional connectivity and complexity with reduced connectivity, yielding a decreased EEG complexity.

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