Noise in Interacting Biological Systems

Biological systems are never isolated, usually oscillatory, and invariably subject to noise and fluctuations that may be of either internal or external origin. We present a methodological framework for studying the deterministic interactions of biological oscillatory systems, while at the same time decomposing and evaluating the noise strength. Based on dynamical Bayesian inference, the method models coupled phase oscillators in the presence of dynamical noise. We demonstrate first the potential and the precision of the method on a predefined numerical system. Then we illustrate its usefulness in detecting how the noise strengths from three human physiological systems – the heart, the lungs and the brain – are affected by general anaesthesia. The results demonstrate the potential of the method for detecting and quantifying noise from biological dynamical systems, quite generally.