Entrainment of the Self-sustained oscillation in aPhysarum polycephalumStrand as a One-dimensionally Coupled Oscillator System

Transient behaviors in the self-sustained oscillation of a plasmodial strand inPhysarum polycephalumhave been investigated for sudden changes in temperature under an isotonic condition. When the temperature is decreased, the period of self-sustained oscillation originally becomes longer than that at steady state, and then changes to be short, while this period simply becomes shorter with an increase in temperature. We have simulated these transient behaviors on the basis of a dynamical model that the plasmodial strand is composed of one-dimensionally coupled oscillators, which are van der Pol equations. It has been made clear that the characteristic responses of the plasmoidal strand in the transient processes reflect nonlinear dynamics, that is an entrainment of the coupled oscillators with frequencies randomly distributed in the system.