/
nmdaca.mod
76 lines (66 loc) · 1.26 KB
/
nmdaca.mod
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: "Standard" NMDA model
: Dual exponential, with voltage-dependent max conductance
: A fraction of the current is carried by calcium
: BPG 22-8-11
TITLE nmda synapse
NEURON {
POINT_PROCESS NMDAca
NONSPECIFIC_CURRENT i
USEION ca READ eca WRITE ica
RANGE g,a,b,gNMDAmax,tcon,tcoff,enmda, mgconc, eta, gamma
RANGE fCa,i,ica
}
UNITS {
(uS) = (microsiemens)
(nA) = (nanoamp)
(mV) = (millivolt)
}
PARAMETER {
fCa = 1.0 : fraction of current is calcium (BPG)
tcon = 3 (ms)
tcoff = 150 (ms)
enmda = 0 (mV)
gNMDAmax = 1 (uS)
mgconc = 1 (mM) : magnesium concentration
eta = 0.33 (/mM)
gamma = 0.06 (/mV)
}
ASSIGNED {
eca (mV)
v (mV)
i (nA)
ica (nA)
g (uS)
factor
}
INITIAL {
LOCAL tp
a=0
b=0
: factor=tcon*tcoff/(tcoff-tcon)
tp = (tcon*tcoff)/(tcoff - tcon) * log(tcoff/tcon)
factor = -exp(-tp/tcon) + exp(-tp/tcoff)
factor = 1/factor
}
STATE {
a
b
}
BREAKPOINT {
LOCAL s
SOLVE states METHOD derivimplicit
s = 1.0/(1+eta*mgconc*exp(-gamma*v))
g = b-a
i = (1-fCa)*gNMDAmax*g*s*(v-enmda)
ica = fCa*gNMDAmax*g*s*(v-enmda)
}
DERIVATIVE states {
a' = -a/tcon
b' = -b/tcoff
}
NET_RECEIVE(wgt) {
LOCAL x
x=wgt*factor
state_discontinuity(a,a+x)
state_discontinuity(b,b+x)
}