Extracting Robust Biomarkers From Multichannel EEG Time Series Using Nonlinear Dimensionality Reduction Applied to Ordinal Pattern Statistics and Spectral Quantities

Front Physiol. 2021 Feb 1:11:614565. doi: 10.3389/fphys.2020.614565. eCollection 2020.


In this study, ordinal pattern analysis and classical frequency-based EEG analysis methods are used to differentiate between EEGs of different age groups as well as individuals. As characteristic features, functional connectivity as well as single-channel measures in both the time and frequency domain are considered. We compare the separation power of each feature set after nonlinear dimensionality reduction using t-distributed stochastic neighbor embedding and demonstrate that ordinal pattern-based measures yield results comparable to frequency-based measures applied to preprocessed data, and outperform them if applied to raw data. Our analysis yields no significant differences in performance between single-channel features and functional connectivity features regarding the question of age group separation.

Keywords: EEG - Electroencephalogram; biomarkers; coherence; functional connectivity; mutual information; nonlinear dimensionality reduction; ordinal pattern statistics; t-SNE (t-distributed stochastic neighbor embedding).