TITLE Sodium transient current for RD Traub et al 2003, 2005
COMMENT
Implemented by Maciej Lazarewicz 2003 (mlazarew@seas.upenn.edu)
fastNashift init to 0 and removed from arg modification Tom Morse 3/8/2006
(for Traub et al 2005)
ENDCOMMENT
INDEPENDENT { t FROM 0 TO 1 WITH 1 (ms) }
UNITS {
(mV) = (millivolt)
(mA) = (milliamp)
}
NEURON {
SUFFIX nafTraub
USEION na READ ena WRITE ina
RANGE gbar, ina,m, h, df, minf, mtau
}
PARAMETER {
: putting as written fastNa_shift = 0: orig -3.5 (mV)
gbar = 0.0 (mho/cm2)
v (mV) ena (mV)
}
ASSIGNED {
ina (mA/cm2)
minf hinf (1)
mtau (ms) htau (ms)
df (mV)
}
STATE {
m h
}
BREAKPOINT {
SOLVE states METHOD cnexp
ina = gbar * m * m * m * h * ( v - ena )
df = v - ena
}
INITIAL {
settables( v )
m = minf
m = 0
h = hinf
}
DERIVATIVE states {
settables( v )
m' = ( minf - m ) / mtau
h' = ( hinf - h ) / htau
}
UNITSOFF
PROCEDURE settables(v1(mV)) {
TABLE minf, hinf, mtau, htau FROM -120 TO 40 WITH 641
minf = 1 / ( 1 + exp( (- v1 - 34.5 ) / 10 ) )
if( v1 < -26.5 ) {
mtau = 0.025 + 0.14 * exp( ( v1 + 26.5 ) / 10 )
} else{
mtau = 0.02 + 0.145 * exp( ( - v1 - 26.5 ) / 10 )
}
: hinf, and htau are shifted 3.5 mV comparing to the paper
hinf = 1 / ( 1 + exp( ( v1 + 59.4 ) / 10.7 ) )
htau = 0.15 + 1.15 / ( 1 + exp( ( v1 + 33.5 ) / 15 ) )
}
UNITSON