TITLE Motoneuron HVA Ltype Calcium channels
:
: The parameters for this current come from V. Booth et al. J Neurophysiol 78:33713385, 1997
: Iterative equations
: I shifted the activation of this current to the same range as N_Ca.mod
:
NEURON {
SUFFIX L_HVA_Ca
USEION ca READ eca WRITE ica
RANGE gcabar
RANGE m_inf
}
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
}
PARAMETER {
gcabar = 0.0003 (mho/cm2) :original = 7e05
eca = 80 (mV)
: celcius = 36 (degC)
dt (ms)
tau_m = 20 (ms)
v (mV)
theta_m = 10 (mV)
kappa_m = 6 (mV) :original = 7
}
STATE {
m
}
ASSIGNED {
ica (mA/cm2)
m_inf
tadj
}
BREAKPOINT {
SOLVE states METHOD cnexp
ica = gcabar * m * (v  eca) :I have tried this as m*m also
}
DERIVATIVE states {
evaluate_fct(v)
m' = (m_inf  m) / tau_m
}
UNITSOFF
INITIAL {
:
: Q10 was assumed to be 3 for both currents
:
: tadj = 3.0 ^ ((celsius36)/ 10 )
evaluate_fct(v)
m = m_inf
}
PROCEDURE evaluate_fct(v(mV)) {
m_inf = 1 / (1 + (Exp((v  theta_m)/ kappa_m))): / tadj
}
FUNCTION vtrap(x,y) {
if (fabs(x/y) < 1e6) {
vtrap = y*(1  x/y/2)
}else{
vtrap = x/(Exp(x/y)1)
}
}
FUNCTION Exp(x) {
if (x < 100) {
Exp = 0
}else{
Exp = exp(x)
}
}
