TITLE Ih-current
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
(mM) = (milli/liter)
}
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
PARAMETER {
dt (ms)
v (mV)
eh = -47 (mV) :ih-reversal potential by Berger
gbar = 0.00015 (mho/cm2) :density on dendrite assuming 150pA current and 150mV driving force (=200pS/um2)
}
NEURON {
SUFFIX ih
NONSPECIFIC_CURRENT Ih
RANGE Ih,gbar
}
STATE {
h
}
ASSIGNED {
Ih (mA/cm2)
}
INITIAL {
h=alpha(v)/(beta(v)+alpha(v))
}
BREAKPOINT {
SOLVE state METHOD cnexp
Ih = gbar*h*(v-eh)
}
FUNCTION alpha(v(mV)) {
alpha = 0.001*6.43*(v+154.9)/(exp((v+154.9)/11.9)-1) :parameters are estimated by direct fitting of HH model to activation time constants and voltage actication curve recorded at 34C by M. Kole
}
FUNCTION beta(v(mV)) {
beta = 0.001*193*exp(v/33.1)
}
DERIVATIVE state { : exact when v held constant; integrates over dt step
h' = (1-h)*alpha(v) - h*beta(v)
}