AUTHOR=Stylianou Orestis , Racz Frigyes Samuel , Kim Keumbi , Kaposzta Zalan , Czoch Akos , Yabluchanskiy Andriy , Eke Andras , Mukli Peter TITLE=Multifractal Functional Connectivity Analysis of Electroencephalogram Reveals Reorganization of Brain Networks in a Visual Pattern Recognition Paradigm JOURNAL=Frontiers in Human Neuroscience VOLUME=15 YEAR=2021 URL=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2021.740225 DOI=10.3389/fnhum.2021.740225 ISSN=1662-5161 ABSTRACT=
The human brain consists of anatomically distant neuronal assemblies that are interconnected via a myriad of synapses. This anatomical network provides the neurophysiological wiring framework for functional connectivity (FC), which is essential for higher-order brain functions. While several studies have explored the scale-specific FC, the scale-free (i.e., multifractal) aspect of brain connectivity remains largely neglected. Here we examined the brain reorganization during a visual pattern recognition paradigm, using bivariate focus-based multifractal (BFMF) analysis. For this study, 58 young, healthy volunteers were recruited. Before the task, 3-3 min of resting EEG was recorded in eyes-closed (EC) and eyes-open (EO) states, respectively. The subsequent part of the measurement protocol consisted of 30 visual pattern recognition trials of 3 difficulty levels graded as Easy, Medium, and Hard. Multifractal FC was estimated with BFMF analysis of preprocessed EEG signals yielding two generalized Hurst exponent-based multifractal connectivity endpoint parameters,