NOVEL FINDINGS ON CARDIORESPIRATORY ROLE SWAPPING BY ASSESSING NONLINEAR DYNAMICAL INTERACTIONS

This paper reports the innovative results of applying nonlinear dynamical theory to heart-rate (HR) and respiratory (RP) sequences to explore Yin–Yang (passive–active) interacting phenomenon of cardiorespiratory function. Organ systems inside human body interact mutually in the manner of swapping the active–passive role, according to Yin–Yang theory in traditional Chinese medicine. Yang as an active source rules over Yin as a passive load. Nonlinear inter-driven (NLID) factor, Γ₍Y/X), based on recurrence analysis is proposed in this study. NLID factor characterizes the nonlinear interactions between two nonlinear dynamical systems, cardiac and respiratory systems. NLID factor is computed by quantifying the HR and RP recurrent plots constructed from phase trajectories based on embedding theorem and phase-space reconstruction. Heterogeneous patterns of HR and RP recurrence plots in continuous-attention task reflect highly unpredictable system dynamics. Heterogeneous HR recurrence patterns are surprisingly associated with the nearly homogeneous RP recurrence plot at resting state, indicating rather weak cardiorespiratory interaction. HR recurrence in Zen exhibits notable regularity in spite of the irregular RP recurrence behaviors. NLID factor reveals prominent Yang energy delivered by RP system that dominates over the cardiac system in Zen-meditation group. Such findings draw our attention to the possibly extraordinary self-regularity power of heart (and autonomic nervous system) in the Zen-meditation state.