TITLE Slow Ca-dependent potassium current
:
: Ca++ dependent K+ current responsible for slow AHP
NEURON {
SUFFIX kcain
USEION k READ ko, ki WRITE ik
USEION ca READ cai
RANGE gbar, po, ik
GLOBAL m_inf, tau_m
}
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
(molar) = (1/liter)
(mM) = (millimolar)
}
ASSIGNED { : parameters needed to solve DE
v (mV)
celsius (degC)
ek (mV)
cai (mM) : initial [Ca]i
ik (mA/cm2)
po
ki (mM)
ko (mM)
m_inf
tau_m (ms)
: h_inf :inactivation
: tau_h (ms)
: taumin
}
PARAMETER {
gbar = 10 (mho/cm2)
: ek (mV)
taumin = 0 (ms) :(150)
b = 0.008 (/ms) : changed oct 17, 2006 for pfc (0.3)
:b = 0.8 : value for CA1 neuron(2006)
: tau_h = 300 (ms)
}
STATE {
m
}
BREAKPOINT {
SOLVE states METHOD cnexp
ek = 25 * log(ko/ki)
po = m*m
ik = gbar*po*(v - ek) : potassium current induced by this channel
}
DERIVATIVE states {
rates(cai)
: m'=(-1/(tau_m))*(m-(m_inf))
m' = (m_inf - m) / tau_m : old equation
: h'=(h_inf - h)/tau_h
}
INITIAL {
rates(cai)
m = 0
: m = m_inf
: h = h_inf
}
PROCEDURE rates(cai(mM)) {
LOCAL a
: a=100
: m_inf=(a*cai*cai)/(a*cai*cai+b)
: tau_m=(1/(a*cai*cai+b))
:old equations
a = cai/b
m_inf = a/(a+1)
: tau_m=600
tau_m = taumin+ 1(ms)*1(mM)*b/(cai+b)
:inactivation
: h_inf= ah/(ah+1)
}