TITLE CA1NaP.mod Persistent sodium current
COMMENT
Persistent Na for CA1 pyramid
Specifications in Lipowsky et al, J.Neurophys 76:2181-2191, 1996
Half-activation voltage can be varied (is -49mV in paper)
BPG 26-5-98
ENDCOMMENT
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
}
NEURON {
SUFFIX CA1NaP
USEION na WRITE ina
RANGE gnaP, ina, ena
GLOBAL mPinf, mPexp
}
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
PARAMETER {
v (mV)
dt (ms)
gnaP = 0.00017 (mho/cm2)
ena = 65 (mV)
vhalf = -49 (mV)
}
STATE {
mP
}
ASSIGNED {
ina (mA/cm2)
mPinf mPexp
}
BREAKPOINT {
SOLVE states
ina = gnaP*mP*(v - ena)
}
UNITSOFF
INITIAL {
rates(v)
mP = mPinf
}
PROCEDURE states() { :Computes state variable mP
rates(v) : at the current v and dt.
mP = mP + mPexp*(mPinf-mP)
}
PROCEDURE rates(v) { :Computes rate and other constants at current v.
:Call once from HOC to initialize "inf" at resting v.
LOCAL alpha, beta
TABLE mPinf, mPexp DEPEND dt FROM -100 TO 50 WITH 150
:"m" sodium activation system
alpha = -1.74*(v-11)/(exp(-(v-11)/12.94)-1)
beta = 0.06*(v-5.9)/(exp((v-5.9)/4.47)-1)
mPinf = 1/(1+exp(-(v-vhalf)/5))
mPexp = 1 - exp(-dt*(alpha+beta))
}
UNITSON