RT Journal Article
SR Electronic
T1 Data-driven spectral analysis for coordinative structures in periodic systems with unknown and redundant dynamics
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 511642
DO 10.1101/511642
A1 Keisuke Fujii
A1 Naoya Takeishi
A1 Benio Kibushi
A1 Motoki Kouzaki
A1 Yoshinobu Kawahara
YR 2019
UL http://biorxiv.org/content/early/2019/01/04/511642.abstract
AB Living organisms dynamically and flexibly operate a great number of components. As one of such redundant control mechanisms, low-dimensional coordinative structures among multiple components have been investigated. However, structures extracted from the conventional statistical dimensionality reduction methods do not reflect dynamical properties in principle. Here we regard coordinative structures in biological periodic systems with unknown and redundant dynamics as a nonlinear limit-cycle oscillation, and apply a data-driven operator-theoretic spectral analysis, which obtains dynamical properties of coordinative structures such as frequency and phase from the estimated eigenvalues and eigenfunctions of a composition operator. First, from intersegmental angles during human walking, we extracted the speed-independent harmonics of gait frequency. Second, we discovered the speed-dependent time-evolving behaviors of the phase on the conventional low-dimensional structures by estimating the eigenfunctions. Our approach contributes to the understanding of biological periodic phenomena with unknown and redundant dynamics from the perspective of nonlinear dynamical systems.