Mode decomposition-based time-varying phase synchronization for fMRI Data

TL;DR

This paper introduces a data-driven mode decomposition method, MVMD, for analyzing time-varying phase synchronization in fMRI data, avoiding traditional frequency band selection issues.

Contribution

It compares various mode decomposition techniques and demonstrates that MVMD provides superior performance for measuring dynamic phase synchronization in brain imaging.

Findings

MVMD outperforms other mode decomposition methods in simulations.

MVMD reliably detects time-varying phase synchronization in rs-fMRI.

The approach offers a data-driven alternative to traditional bandpass filtering.

Abstract

Recently there has been significant interest in measuring time-varying functional connectivity (TVC) between different brain regions using resting-state functional magnetic resonance imaging (rs-fMRI) data. One way to assess the relationship between signals from different brain regions is to measure their phase synchronization (PS) across time. However, this requires the \textit{a priori} choice of type and cut-off frequencies for the bandpass filter needed to perform the analysis. Here we explore alternative approaches based on the use of various mode decomposition (MD) techniques that circumvent this issue. These techniques allow for the data driven decomposition of signals jointly into narrow-band components at different frequencies, thus fulfilling the requirements needed to measure PS. We explore several variants of MD, including empirical mode decomposition (EMD), bivariate EMD (BEMD), noise-assisted multivariate EMD (na-MEMD), and introduce the use of multivariate variational mode decomposition (MVMD) in the context of estimating time-varying PS. We contrast the approaches using a series of simulations and application to rs-fMRI data. Our results show that MVMD outperforms other evaluated MD approaches, and further suggests that this approach can be used as a tool to reliably investigate time-varying PS in rs-fMRI data.