Reassessing Global Field Synchronization as a Phase-Synchrony EEG Metric: Mathematical Review and Empirical Counterexamples With Implications for Wearable Pain Monitoring.

Authors

Seong Jin Cho, Kwang-Ho Choi, Min Ji Kim, O Sang Kwon, Suk Yun Kang, Hee Young Kim, Yeonhee Ryu

Published in

Pain research & management. Volume 2026. Issue 1. Pages e8799914.

Abstract

Integrative pain care emphasizes longitudinal monitoring to personalize multimodal treatment and reduce medication-related risk. Wearable electroencephalography (EEG) could enable scalable, real-time neurophysiological tracking but requires connectivity features that are computationally simple and mechanistically valid. Global field synchronization (GFS) is widely used and often interpreted as a global phase-synchrony index, yet its construct validity remains unclear.
To evaluate whether GFS validly represents EEG phase synchronization and discuss implications for wearable monitoring in integrative pain management.
We conducted construct validation using (i) synthetic Fourier-domain multichannel data designed to generate counterexamples and (ii) empiricalresting-state EEG data from healthy subjects (32 channels, eyes closed). Phase dispersion was quantified by circular standard deviation (CSD). Simulations assessed GFS-CSD correspondence under rotations (0°-180°) and scaling (1-5). Empirical EEG analyses computed GFS and CSD across 1-50 Hz and evaluated their relationships by frequency band.
In simulations, GFS was invariant to rotations that substantially changed CSD but varied strongly with scaling, whereas CSD changed minimally, indicating that GFS and phase dispersion can dissociate. In empirical resting-state EEG, an expected inverse relationship between GFS and CSD was not consistently observed across delta, theta, alpha, beta, or gamma bands. At a single frequency, examples showed that similar GFS values could correspond to markedly different phase patterns depending on the point cloud's location and distribution.
GFS does not generally serve as a valid proxy for EEG phase synchronization, thereby limiting its mechanistic interpretation as a wearable connectivity biomarker. For integrative pain monitoring and decision support, rigorous construct validation should precede clinical translation, and alternative phase-based indices with real-world robustness are needed.

PMID:
42773883
Bibliographic data and abstract were imported from PubMed on 23 Sep 2026.

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