Here we add excitation cI(t) with period T
to the FHN system
du/dt = F(u, v) + c I(t) =
u(1 - u)(u - a) - v + cI(t),
dv/dt = H(u, v) = ε (bu - v),
I(t) ~ [cos(πt/T)]^{500},
_{-δ }∫^{ δ}I(t)dt = 1. For small T the system is not ready for the second excitation cycle.
a
b
ε
c
T

dt
Ymin
Ymax
field
Again to the left the phase plane of the system is shown.
F(u,v) = 0 null cline is the red line and
H(u,v) = 0 null cline is the green line.
To the right u(t) excitation (black) and v(t)
recovery (blue) variables are plotted. You can explore the model for
different parameter values.
Heart rhythmsupdated 3 Dec 2011