# Izhikevich's Na_p + K (Persistent Sodium + Potassium current) model
#  see Dynamical Systems in Neuroscience, figure 6.16 and 4.14b

# Applied current
params iapp=43
# Conductances
params gl=1,gna=4,gk=4,
# Reversal potentials
params el=-78,ena=60,ek=-90
# Capacitance
params c=1
# Sodium activation parameters
params vhalf_m=-30,k_m=7
# Potassium activation parameters
params vhalf_n=-45,k_n=5

# Sodium activation function
minf(v)=1/(1+exp((vhalf_m-v)/k_m))

# Potassium activation function
ninf(v)=1/(1+exp((vhalf_n-v)/k_n))

# Potassium time constant
tau_n(v)=1

v' = (iapp-gl*(v-el)-gna*minf(v)*(v-ena)-gk*n*(v-ek))/c
n'= (ninf(v)-n)/tau_n(v)

@ TOTAL=30,DT=.05,xlo=-90,xhi=20,ylo=-.25,yhi=1.2
@ xplot=v,yplot=n
set vvst {xplot=t,yplot=v,xlo=0,xhi=100,ylo=-.6,yhi=.5,total=100 \
	dt=.5,meth=qualrk,iapp=.1}
done