# Deterministic Morris-Lecar model follows Rinzel and Ermentrout's
# chapter in Koch & Segev.  Stochastic ion channel dynamics added
# using Langevin formulation 

# for stochastic excitability, oscillations, and bistability use
# iapp = 10, 12, 10 and v3 = 10, 10, 15        

v(0)=-40 
w(0)=1

wiener b

params n=100
params v1=-1,v2=15,v3=10,v4=14.5,gca=1.33,phi=.333
params vk=-70,vl=-50,iapp=10,gk=2.0,gl=.5,om=1
minf(v)=.5*(1+tanh((v-v1)/v2))
# The 0.05 is a modification needed to lift w nullcline
# so that stochastic excitability can be realized  
ninf(v)=.5*(1+tanh((v-v3)/v4))+0.05
lamn(v)= phi*cosh((v-v3)/(2*v4))
ica=gca*minf(v)*(v-100)
v'=  (iapp+gl*(vl-v)+gk*w*(vk-v)-ica)*om
w'= (lamn(v)*(ninf(v)-w))*om+sqrt(lamn(v)*((1-2*ninf(v))*w+ninf(v))/n)*b
aux I_ca=ica
@ total=500,trans=0,DT=.01,xlo=0,xhi=500,ylo=-60,yhi=50 
@ maxstore=1000000,bounds=10000
@ xplot=t,yplot=v

done