TITLE AMPA receptor with presynaptic shortterm plasticity
COMMENT
AMPA receptor conductance using a dualexponential profile
Presynaptic shortterm plasticity based on Fuhrmann et al, 2002
Written by Paulo Aguiar and Mafalda Sousa, IBMC, May 2008
pauloaguiar@fc.up.pt ; mafsousa@ibmc.up.pt
ENDCOMMENT
COMMENT
for one synaptic event and zero initial conditions A=B=0,
max conductance is reached for t = tp and is equal to the
step increase of A and B divided by factor, ie weight or weight*Pv
ENDCOMMENT
NEURON {
POINT_PROCESS AMPA_DynSyn
RANGE tau_rise, tau_decay
RANGE U1, tau_rec, tau_fac, stp
RANGE i, g, e
NONSPECIFIC_CURRENT i
}
PARAMETER {
tau_rise = 0.1 (ms) : dualexponential conductance profile
tau_decay = 5.0 (ms) : IMPORTANT: tau_rise < tau_decay
U1 = 1.0 (1) : The parameter U1, tau_rec and tau_fac define _
tau_rec = 0.1 (ms) : the presynaptic shortterm plasticity _
tau_fac = 0.1 (ms) : mechanism (see Fuhrmann et al, 2002)
e = 0.0 (mV) : AMPA synapse reversal potential
stp = 1.0 (1) : boolean for synaptic plasticity
}
ASSIGNED {
v (mV)
i (nA)
g (umho)
factor
}
STATE {
A : state variable to construct the dualexponential profile
B :
}
INITIAL{
LOCAL tp
A = 0
B = 0
tp = (tau_rise*tau_decay)/(tau_decaytau_rise)*log(tau_decay/tau_rise)
factor = exp(tp/tau_rise)+exp(tp/tau_decay)
factor = 1/factor
}
BREAKPOINT {
SOLVE state METHOD cnexp
g = BA
i = g*(ve)
}
DERIVATIVE state{
A' = A/tau_rise
B' = B/tau_decay
}
NET_RECEIVE (weight, Pv, P, Use, t0 (ms)){
INITIAL{
P=1
Use=0
t0=t
}
if(stp){
Use = Use * exp((tt0)/tau_fac)
Use = Use + U1*(1Use)
P = 1(1 P) * exp((tt0)/tau_rec)
Pv = Use * P
P = P  Use * P
t0 = t
A = A + weight*factor*Pv
B = B + weight*factor*Pv
} else {
A = A + weight*factor
B = B + weight*factor
}
}
