Synchronization of brain electrical activity between two hemispheres in different frequency bands

In this paper we address the problem of synchronization in electroencephalogram (EEG) recorded from two brain hemispheres, where the goal is to study if the synchrony takes place for symmetric and asymmetric channels, and to analyze synchronization characteristics for all main EEG rhythms. In our approach we use filtration to separate rhythm´s frequency content, followed by calculation of Single-Trial Phase-Locking Value (SPLV) to quantify phase synchronization. We analyzed background EEG from eight matched healthy volunteers, first comparing synchronization between symmetric/asymmetric channels and surrogate signals, and then comparing synchronization between symmetric and asymmetric channels itself. The presence of synchronization was validated by Kruskal-Wallis test to compare SPLV in symmetric vs. asymmetric channels, resulting in statistically significant distinction (p≤0.001) in all frequency bands, except gamma rhythm for which p-value was p≤0.05.