On the behavior of mRIC--a simple model of living pacemakers driven by periodic pulse trains.

The main feature separating a living pacemaker from other oscillators is the fact that the former has not only the oscillatory property but also slow and fast changes of the membrane potential corresponding to the sub- and suprathreshold regions. We propose a simple mathematical model called mRIC and show that the model exhibited the essential feature of pacemakers generating spikes at constant time intervals. The behavior of the model driven by periodic pulse trains is analysed using the phase transition curve.