COMMENT
A synaptic current with two dual exponential function conductances,
representing nonvoltagedependent AMPA and voltagedependent NMDA
components. The basic dual exponential conductance is given by:
g = 0 for t < onset and
g = gmax*((tau1*tau2)/(tau1tau2)) *
(exp((tonset)/tau1)exp((tonset)/tau2))
for t > onset (tau1 and tau2 are fast and slow time constants)
The synaptic current is:
i = (gA + gN) * (v  e) i(nanoamps), g(micromhos);
NMDA model taken from Mel, J. Neurophys. 70:10861101, 1993
BPG 11200
ENDCOMMENT
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
NEURON {
POINT_PROCESS ANSynapse
RANGE onset, gmax, e, i, g, gA, gN, tau1, tau2, Ntau1, Ntau2, eta, Mg, gamma, Nfrac
NONSPECIFIC_CURRENT i
}
UNITS {
(nA) = (nanoamp)
(mV) = (millivolt)
(umho) = (micromho)
}
PARAMETER {
onset=0 (ms)
tau1=.2 (ms) <1e3,1e6>
tau2=2 (ms) <1e3,1e6>
Nfrac=0.5
Ntau1=.66 (ms) <1e3,1e6>
Ntau2=80 (ms) <1e3,1e6>
eta=0.33 (/mM)
Mg=1 (mM)
gamma=0.06 (/mV)
gmax=0 (umho) <0,1e9>
e=0 (mV)
v (mV)
}
ASSIGNED { i (nA) g (umho) gA (umho) gN (umho) Agmax (umho) Ngmax (umho)}
INITIAL {
Agmax = (1Nfrac)*gmax
Ngmax = Nfrac*gmax
}
BREAKPOINT {
gA = Agmax*((tau1*tau2)/(tau1tau2))*duale((tonset)/tau1,(tonset)/tau2)
gN = Ngmax*((Ntau1*Ntau2)/(Ntau1Ntau2))*duale((tonset)/Ntau1,(tonset)/Ntau2)
gN = gN / (1 + (eta*Mg*exp(gamma*v)))
g = gA + gN
i = g*(v  e)
}
FUNCTION duale(x,y) {
if (x < 0  y < 0) {
duale = 0
}else{
duale = exp(x)  exp(y)
}
}
