# Simplified 2D HH model
# formatted for use with XPPAUT

# Parameters as in the model of Figure 8, Lundstrom et al, J Comp Neurosci
# Note: the z variable introduces stimulus noise and must be removed for bifurcation analysis

wiener nz
v' = -(Gl*(v - El) + Gk*n^4*(v - Ek) + Gna*minf^3*h*(v - Ena))/cm + i/cm + z
n' = (ninf - n) / ntau  
z'=-z/tau + nsig*sqrt(2/tau)*nz
par tau=1

par i=0, mVh=-40,mk=7,nVh=-45,nk=15, Gna=50,Gk=36,Gl=5,Ena=50,Ek=-77,El=-54,cm=1
par nsig=0

par Cbase=3,Camp=50,Vmax=-50,sig=1

ntau = Cbase + Camp*exp(-(Vmax - V)^2/sig^2)
ninf = 1.0 / (1+exp( (nVh - v)/nk) )
minf = 1.0 / (1+exp( (mVh - v)/mk) )
h = .89 - 1.1*n

init v=-65,n=0.3

@ meth=euler,total=20ee0,dt=.005,nout=50