Synchronization in biological systems

Abstract

Synchronization, the adjustment of rhythms via coupling, is an essentially nonlinear effect in coupled dynamical systems. Synchronization is observed in many systems, for example the moon's periods of rotation and revolution, in pendulums suspended from a common support, in swarms of fireflies that flash in unison, and in biological circadian rhythms. Circadian rhythms are periodic fluctuations in multiple physiological systems that have evolved as a consequence of the daily rotation of the earth. These rhythms have been observed in organisms ranging from cyanobacteria to man. In this thesis we will present a conceptually simple model of circadian rhythms to yield insight into the activity patterns of mice in light and food restriction experiments. The model consists of two coupled van der Pol oscillators that are driven by an external periodic influence representing food availability. The results of the model are compared to circadian data of mice collected by Dr. Abel Bult-Ito (Institute of Artic Biology).