QLS Seminar Series - Hanspeter Herzel

Oscillator theory meets biological rhythms

Hanspeter Herzel, Institute for Theoretical Biology (ITB)
Tuesday March 19, 12-1pm
Zoom Link: https://mcgill.zoom.us/j/86855481591
In Person: 550 Sherbrooke, Room 189

Abstract: Oscillations in biological systems appear on many time scales from millisecond vibrations of vocal folds, via heart rhythms, to circadian rhythms with a period of 24 hours. Oscillator theory (limit cycles, Hopf bifurcation, Arnold's tongues) provides a framework to understand the emergence and interaction of biomedical rhythms. In the first part, I review oscillator theory using examples from voice production, physiological rhythms, and transcriptional feedback loops. I introduce conceptual mathematical models (Poincare oscillator, Goodwin model) illustrating the role of nonlinearities, feedbacks, and resonances. In the second part, I describe circadian clocks as a coupled oscillator system. Even single cells exhibit rhythms due to genetic feedback loops. The coupling of SCN neurons allows the adaptation to light-dark cycles and the orchestration of body clocks. Oscillator theory helps to understand the features of chronotypes and jetlag. Finally, simulations can contribute to the optimization of chronotherapy.