Rhythmogenesis of Deterministic Breathing Patterns

Abstract

The physiological act of breathing functionally can be conceived as being governed by separate central rhythm and pattern generators within the brainstem/spinal cord which are subject to nonlinear afferent feedback and suprapontine feedforward inputs of varying coupling strengths. This complex network sculptures the spatiotemporal configurations and movements of the diaphragm and chest wall to effect the exchange of gases between alveolar space and the environment. As is common for many intrinsically stable physiological systems, the respiratory controller is characterized by nonstationarities and transients, the presence of which may preclude the accuracy of otherwise useful ergodic techniques in the analysis of complex systems. From the geometric perspective, however, recurrence plots are robust against dynamical transients and system drifts, and they are proving to be very helpful in assessing the dynamics of breathing patterns. Their general applicability to numerous other rhythmical phenomena in the physiological realm (cardiovascular, central neural, gastrointestinal systems, etc.) is intuitive. Finally, Shannon entropy, a gauge of randomness and information, and percent recurrence are introduced as possible measures of complexity for biological systems in quasi-steady states or transition phases.