Temporal dynamicsdE/dt = F(E, n) = [A - (n/nb)M][1 - tanh(E - 3)]E2/2 - E,
dn/dt = H(E, n) = ε [Θ(E - 1) - n].
where A = 1.5415.
Below you can explore the model for different parameter values. To the left the phase plane of the system is shown. F(E,n) = 0 null cline is the red line and H(E,n) = 0 null cline is the green line. To the right E(t)/4 excitation (black) and n(t) recovery (blue) variables are plotted. The script makes 800 time steps dt.
dt Eo no Ymax field
The system makes an excitation cycle and goes to the stable fixed point (E=0, n=0).
 Alain Karma
Spiral Breakup in Model Equations of Action Potential Propagation in
Phys.Rev.Lett. 71, 1103 (1993)