TITLE klt.mod The low threshold conductance of cochlear nucleus neurons
COMMENT
NEURON implementation of Jason Rothman's measurements of VCN conductances.
This file implements the average brain sodium current used in the Rothman model.
In the absence of direct measurements in the VCN, this is a fair assumption.
The model differs from the one used in Rothman et al, (1993) in that the steep
voltage dependence of recovery from inactivation in that model is missing. This
may affect the refractory period. To use the other model, use najsr.mod instead.
Original implementation by Paul B. Manis, April (JHU) and Sept, (UNC)1999.
File split implementaiton, April 1, 2004.
Contact: pmanis@med.unc.edu
ENDCOMMENT
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
(nA) = (nanoamp)
}
NEURON {
SUFFIX na
USEION na READ ena WRITE ina
RANGE gnabar, gna, ina
GLOBAL hinf, minf, htau, mtau
}
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
PARAMETER {
v (mV)
celsius = 22 (degC) : model is defined on measurements made at room temp in Baltimore
dt (ms)
ena (mV)
gnabar = 0.07958 (mho/cm2) <0,1e9>
}
STATE {
m h
}
ASSIGNED {
ina (mA/cm2)
gna (mho/cm2)
minf hinf
mtau (ms) htau (ms)
}
LOCAL mexp, hexp
BREAKPOINT {
SOLVE states
gna = gnabar*(m^3)*h
ina = gna*(v  ena)
}
UNITSOFF
INITIAL {
trates(v)
m = minf
h = hinf
}
PROCEDURE states() { :Computes state variables m, h, and n
trates(v) : at the current v and dt.
m = m + mexp*(minfm)
h = h + hexp*(hinfh)
VERBATIM
return 0;
ENDVERBATIM
}
LOCAL q10
PROCEDURE rates(v) { :Computes rate and other constants at current v.
:Call once from HOC to initialize inf at resting v.
q10 = 3^((celsius  22)/10) : if you don't like room temp, it can be changed!
: average sodium channel
minf = 1 / (1+exp((v + 38) / 7))
hinf = 1 / (1+exp((v + 65) / 6))
mtau = (10 / (5*exp((v+60) / 18) + 36*exp((v+60) / 25))) + 0.04
htau = (100 / (7*exp((v+60) / 11) + 10*exp((v+60) / 25))) + 0.6
}
PROCEDURE trates(v) { :Computes rate and other constants at current v.
:Call once from HOC to initialize inf at resting v.
LOCAL tinc
TABLE minf, mexp, hinf, hexp
DEPEND dt, celsius FROM 150 TO 150 WITH 300
rates(v) : not consistently executed from here if usetable_hh == 1
: so don't expect the tau values to be tracking along with
: the inf values in hoc
tinc = dt * q10
mexp = 1  exp(tinc/mtau)
hexp = 1  exp(tinc/htau)
}
FUNCTION vtrap(x,y) { :Traps for 0 in denominator of rate eqns.
if (fabs(x/y) < 1e6) {
vtrap = y*(1  x/y/2)
}else{
vtrap = x/(exp(x/y)  1)
}
}
UNITSON
