Entrainment of noise-induced and limit cycle oscillators under weak noise

TL;DR

This paper compares how noise-induced and limit cycle oscillators respond to external periodic forcing, revealing differences in their entrainment behaviors and the effects of noise on their synchronization properties.

Contribution

It provides a detailed analysis of the entrainment properties of noise-induced versus limit cycle oscillators under different types of external forcing.

Findings

Noise-induced oscillators show only one-to-one entrainment with additive forcing.

Limit cycle oscillators can entrain to any ratio under external forcing.

Noise blurs entrainment but clear regions exist for limit cycles with moderate noise.

Abstract

Theoretical models that describe oscillations in biological systems are often either a limit cycle oscillator, where the deterministic nonlinear dynamics gives sustained periodic oscillations, or a noise-induced oscillator, where a fixed point is linearly stable with complex eigenvalues and addition of noise gives oscillations around the fixed point with fluctuating amplitude. We investigate how each class of model behaves under the external periodic forcing, taking the well-studied van der Pol equation as an example. We find that, when the forcing is additive, the noise-induced oscillator can show only one-to-one entrainment to the external frequency, in contrast to the limit cycle oscillator which is known to entrain to any ratio. When the external forcing is multiplicative, on the other hand, the noise-induced oscillator can show entrainment to a few ratios other than one-to-one, while the limit cycle oscillator shows entrain to any ratio. The noise blurs the entrainment in general, but clear entrainment regions for limit cycles can be identified as long as the noise is not too strong.