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: Reference: Reuveni, Friedman, Amitai, and Gutnick, J.Neurosci. 1993
NEURON {
SUFFIX Ca_HVA
USEION ca READ eca WRITE ica
RANGE gbar, g, ica
}
UNITS {
(S) = (siemens)
(mV) = (millivolt)
(mA) = (milliamp)
}
PARAMETER {
gbar = 0.00001 (S/cm2)
}
ASSIGNED {
v (mV)
eca (mV)
ica (mA/cm2)
g (S/cm2)
mInf
mTau
mAlpha
mBeta
hInf
hTau
hAlpha
hBeta
}
STATE {
m
h
}
BREAKPOINT {
SOLVE states METHOD cnexp
g = gbar*m*m*h
ica = g*(v-eca)
}
DERIVATIVE states {
rates()
m' = (mInf-m)/mTau
h' = (hInf-h)/hTau
}
INITIAL{
rates()
m = mInf
h = hInf
}
PROCEDURE rates(){
UNITSOFF
: if((v == -27) ){
: v = v+0.0001
: }
:mAlpha = (0.055*(-27-v))/(exp((-27-v)/3.8) - 1)
mAlpha = 0.055 * vtrap(-27 - v, 3.8)
mBeta = (0.94*exp((-75-v)/17))
mInf = mAlpha/(mAlpha + mBeta)
mTau = 1/(mAlpha + mBeta)
hAlpha = (0.000457*exp((-13-v)/50))
hBeta = (0.0065/(exp((-v-15)/28)+1))
hInf = hAlpha/(hAlpha + hBeta)
hTau = 1/(hAlpha + hBeta)
UNITSON
}
FUNCTION vtrap(x, y) { : Traps for 0 in denominator of rate equations
UNITSOFF
if (fabs(x / y) < 1e-6) {
vtrap = y * (1 - x / y / 2)
} else {
vtrap = x / (exp(x / y) - 1)
}
UNITSON
}
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