: A conductance
NEURON {
SUFFIX KA
USEION k WRITE ik
RANGE gbar, minf, mtau, hinf, htau, i, g, m, h
GLOBAL erev
}
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
}
PARAMETER {
erev = -85 (mV) : effective Ek
gbar = 0 (S/cm2)
vmin = -100 (mV) : for look-up table
vmax = 100 (mV)
}
ASSIGNED {
v (mV)
i (mA/cm2)
ik (mA/cm2)
g (S/cm2)
malpha (/ms)
mbeta (/ms)
minf
mtau (ms)
halpha (/ms)
hbeta (/ms)
hinf
htau (ms)
}
STATE { m h }
INITIAL {
rates(v)
m = minf
h = hinf
}
BREAKPOINT {
SOLVE states METHOD cnexp
g = gbar*m*h
ik = g*(v - erev)
i = ik
}
DERIVATIVE states {
rates(v)
m' = (minf - m)/mtau
h' = (hinf - h)/htau
}
PROCEDURE rates(v (mV)) {
TABLE minf, mtau, hinf, htau
FROM vmin TO vmax WITH 199
malpha = -0.05*(v+25)/(exp(-(v+25)/15)-1)
mbeta = 0.1*(v+15)/(exp((v+15)/8)-1)
mtau = 1/(malpha + mbeta)
minf = malpha/(malpha + mbeta)
halpha = (1.5e-4)/exp((v+13)/15)
hbeta = 0.06/(exp(-(v+68)/12)+1)
htau = 1/(halpha + hbeta)
hinf = halpha/(halpha + hbeta)
}