Spontaneous sarcomere dynamics

TL;DR

This paper models the spontaneous oscillations of sarcomeres, revealing complex bifurcation behaviors that could explain muscle dynamics beyond neural control.

Contribution

It introduces a force-dependent detachment model for sarcomere dynamics and analyzes its bifurcation structure, highlighting novel oscillatory behaviors.

Findings

Identification of Hopf bifurcations in sarcomere oscillations

Discovery of canard explosions and gluing bifurcations

Implications for understanding muscle behavior without neural signals

Abstract

Sarcomeres are the basic force generating units of striated muscles and consist of an interdigitating arrangement of actin and myosin filaments. While muscle contraction is usually triggered by neural signals, which eventually set myosin motors into motion, isolated sarcomeres can oscillate spontaneously between a contracted and a relaxed state. We analyze a model for sarcomere dynamics, which is based on a force-dependent detachment rate of myosin from actin. Our numerical bifurcation analysis of the spontaneous sarcomere dynamics reveals notably Hopf bifurcations, canard explosions, and gluing bifurcations. We discuss possible implications for experiments.