FitzHugh-Nagumo Excitability
Excitable cell model — action potentials, phase portraits, and spiral waves
FitzHugh-Nagumo
1D Cell
2D Grid
Stimulus I:
0.5
Recovery a:
0.7
Time scale ε:
0.08
Coupling D (2D):
0.5
Stimulate cell
Reset grid
Init spiral wave
dv/dt
= v − v³/3 − w + I
dw/dt
= ε(v + a − bw)
v: fast membrane potential
w: slow recovery variable
Near threshold: small stimuli decay; above threshold: full action potential fires. Spiral waves emerge in 2D excitable media (like cardiac tissue).