COMMENT
Ca channel from Manor (Rinzel, Segev, Yarom) 1997
Channel can cause sub-threshold oscillations in interplay with the leak
B. Torben-Nielsen @ HUJI, 7-10-2010
ENDCOMMENT
NEURON {
SUFFIX ioCa
:USEION ca WRITE ica
NONSPECIFIC_CURRENT i
RANGE mMidV,gbar,g,i,minf,hinf,tauh,m,h,ecas : now i can access these variables
}
UNITS {
(S) = (siemens)
(mS) = (millisiemens)
(mV) = (millivolt)
(mA) = (milliamp)
}
PARAMETER {
ecas = 120 (mV)
gbar = 0.4 (mS/cm2)
mMidV=-61 (mV) : -61 default from mnaor. can be set to other values, e.g., to test 'windowness' of the current
}
ASSIGNED {
v (mV)
i (mA/cm2)
g (mS/cm2)
minf
hinf
tauh (ms)
}
STATE {
m
h
}
INITIAL {
rates(v)
h = hinf
m = minf
}
BREAKPOINT {
rates(v)
SOLVE states METHOD cnexp
g = gbar *minf*h
i = g * (v - ecas)*(0.001)
:ica = i
}
DERIVATIVE states {
h' = (hinf -h)/tauh
}
PROCEDURE rates(v (mV)) {
: updates formulas with earlier activation, e_r=-70, e_l=-78 (i.e., at lower amplitudes)
:hinf =1/( 1+exp( (v+100.5)/8.6 ) )
:minf = 1/( (1+exp((-75.5-v)/4.2)) *(1+exp((-75.5-v)/4.2))* (1+exp((-75.5-v)/4.2)) )
:tauh=55+30*(1/( 1+exp((v+99.0)/7.3) ))*exp((v+175.0)/30.0)
: below the original ones
UNITSOFF
hinf =1/( 1+exp( (v+85.5)/8.6 ) ) :85.5
tauh=40+30*(1/( 1+exp((v+84.0)/7.3) ))*exp((v+160.0)/30.0)
minf = 1/( (1+exp((mMidV-v)/4.2)) *(1+exp((mMidV-v)/4.2))* (1+exp((mMidV-v)/4.2)) )
m = minf
UNITSON
}