TITLE AMPA and NMDA receptor with presynaptic short-term plasticity
COMMENT
AMPA and NMDA receptor conductance using a dual-exponential profile
presynaptic short-term plasticity based on Fuhrmann et al. 2002
Implemented by Srikanth Ramaswamy, Blue Brain Project, July 2009
Etay: changed weight to be equal for NMDA and AMPA, gmax accessible in Neuron
Tuomo: Changed the data structure so that each instance of this synapse corresponds
to a group of synapses. The previous activation time and variables Pv and u
are saved for each "sub-synapse" in this synapse group. Added function
setVec() which saves the pointer to these data.
Tuomo: In addition to the synapse-wise data, also the past and future activation
times are saved. This allows more complicated synapse activation time
distributions than stationary Poissonian activation times (e.g., oscillatory
Poissonian inputs). Added function setVec2 which sets the vector of IDs of
synapses that are activated. This way, whenever the synapse group is activated,
the program checks whose turn (with which ID) it is to fire.
ENDCOMMENT
NEURON {
POINT_PROCESS ProbUDFsyn2groupdet
RANGE tau_r, tau_d, Nsyns, Nevents, eventCounter
RANGE Use, u, Dep, Fac, u0
RANGE i, g, e, gmax
NONSPECIFIC_CURRENT i
POINTER rng
}
PARAMETER {
tau_r = 0.2 (ms) : dual-exponential conductance profile
tau_d = 1.7 (ms) : IMPORTANT: tau_r < tau_d
Use = 1.0 (1) : Utilization of synaptic efficacy (just initial values! Use, Dep and Fac are overwritten by BlueBuilder assigned values)
Dep = 100 (ms) : relaxation time constant from depression
Fac = 10 (ms) : relaxation time constant from facilitation
e = 0 (mV) : AMPA and NMDA reversal potential
gmax = .001 (uS) : weight conversion factor (from nS to uS)
u0 = 0 :initial value of u, which is the running value of Use
Nsyns = 10 : How many synapses are there actually (the size of "space" divided by three)
Nevents = 0 : How many events will there be (the size of "space2")
}
COMMENT
The Verbatim block is needed to generate random nos. from a uniform distribution between 0 and 1
for comparison with Pr to decide whether to activate the synapse or not
ENDCOMMENT
VERBATIM
#include<stdlib.h>
#include<stdio.h>
#include<math.h>
double nrn_random_pick(void* r);
void* nrn_random_arg(int argpos);
extern int ifarg(int iarg);
extern int vector_capacity(void* vv);
extern void* vector_arg(int iarg);
ENDVERBATIM
ASSIGNED {
v (mV)
i (nA)
g (uS)
factor
rng
weight_NMDA
space : A pointer to the vector containing the synapse times. Note that the underlying vector should not be touched after initialization by setVec().
space2 : A pointer to the vector containing the event IDs. Note that the underlying vector should not be touched after initialization by setVec2().
eventCounter : An index for space2 (counts the passed events)
}
STATE {
A : state variable to construct the dual-exponential profile - decays with conductance tau_r_AMPA
B : state variable to construct the dual-exponential profile - decays with conductance tau_d_AMPA
}
INITIAL{
LOCAL tp
A = 0
B = 0
tp = (tau_r*tau_d)/(tau_d-tau_r)*log(tau_d/tau_r) :time to peak of the conductance
factor = -exp(-tp/tau_r)+exp(-tp/tau_d) : Normalization factor - so that when t = tp, gsyn = gpeak
factor = 1/factor
eventCounter = 0
}
BREAKPOINT {
SOLVE state METHOD cnexp
g = gmax*(B-A) :compute time varying conductance as the difference of state variables B and A
i = g*(v-e) :compute the driving force based on the time varying conductance, membrane potential, and reversal
}
DERIVATIVE state{
A' = -A/tau_r
B' = -B/tau_d
}
NET_RECEIVE (weight, Pv, Pr, u, myInd, tsyn (ms)){
INITIAL{
Pv=1
u=u0
tsyn=t
eventCounter=0
}
:Randomize which of the synapses is activated. Note that an additional random number is generated by rand() - this may interfere with the random number order in parallel simulations.
VERBATIM
void** vv = (void**)(&space);
void** vv2 = (void**)(&space2);
double *x;
int nx = vector_instance_px(*vv, &x);
double *x2;
int nx2 = vector_instance_px(*vv2, &x2);
int myInd = 0;
if (eventCounter < nx2)
myInd = x2[(int)eventCounter];
else printf("eventCounter >= nx2! t = %lf\n",t);
eventCounter++;
_args[4] = myInd;
_args[5] = x[myInd]; //tsyn
_args[1] = x[myInd+(int)Nsyns]; //Pv
_args[3] = x[myInd+2*((int)Nsyns)]; //u
ENDVERBATIM
::printf("NET_RECEIVE_beg: Pv = %g, Pr = %g, u = %g, myInd = %g, tsyn = %g, t = %g\n", Pv, Pr, u, myInd, tsyn, t)
:printf("NET_RECEIVE_beg: myInd = %g/%g, Pv = %g, u = %g, tsyn = %g, t = %g. ", myInd, Nsyns, Pv, u, tsyn, t)
: calc u at event-
if (Fac > 0) {
u = u*exp(-(t - tsyn)/Fac) :update facilitation variable if Fac>0 Eq. 2 in Fuhrmann et al.
} else {
u = Use
}
if(Fac > 0){
u = u + Use*(1-u) :update facilitation variable if Fac>0 Eq. 2 in Fuhrmann et al.
}
Pv = 1 - (1-Pv) * exp(-(t-tsyn)/Dep) :Probability Pv for a vesicle to be available for release, analogous to the pool of synaptic
:resources available for release in the deterministic model. Eq. 3 in Fuhrmann et al.
Pr = u * Pv :Pr is calculated as Pv * u (running value of Use)
Pv = Pv - u * Pv :update Pv as per Eq. 3 in Fuhrmann et al.
:printf("Pv = %g\n", Pv)
:printf("Pr = %g\n", Pr)
tsyn = t
if (erand() < Pr){
A = A + weight*factor
B = B + weight*factor
:::printf("Inh Released! Pr = %g, Pv = %g, u = %g, myInd = %g, tsyn = %g\n", Pr, Pv, u, myInd, tsyn)
::printf("Inh Released!\n")
:printf ( "R! Pr = %g\n" , Pr )
} else {
:::printf("Inh Not released! Pr = %g, Pv = %g, u = %g, myInd = %g, tsyn = %g\n", Pr, Pv, u, myInd, tsyn)
::printf("Inh Not released! value = %g, Pr = %g\n", erand(), Pr )
:printf ( "NR! Pr = %g\n" , Pr )
}
VERBATIM
x[myInd] = t;
x[myInd+(int)Nsyns] = _args[1];
x[myInd+2*((int)Nsyns)] = _args[3];
ENDVERBATIM
}
PROCEDURE setRNG() {
VERBATIM
{
/**
* This function takes a NEURON Random object declared in hoc and makes it usable by this mod file.
* Note that this method is taken from Brett paper as used by netstim.hoc and netstim.mod
* which points out that the Random must be in negexp(1) mode
*/
void** pv = (void**)(&_p_rng);
if( ifarg(1)) {
*pv = nrn_random_arg(1);
} else {
*pv = (void*)0;
}
}
ENDVERBATIM
}
FUNCTION erand() {
VERBATIM
//FILE *fi;
double value;
if (_p_rng) {
/*
:Supports separate independent but reproducible streams for
: each instance. However, the corresponding hoc Random
: distribution MUST be set to Random.negexp(1)
*/
value = nrn_random_pick(_p_rng);
//fi = fopen("RandomStreamMCellRan4.txt", "w");
//fprintf(fi,"random stream for this simulation = %lf\n",value);
//printf("random stream for this simulation = %lf\n",value);
return value;
}else{
ENDVERBATIM
: the old standby. Cannot use if reproducible parallel sim
: independent of nhost or which host this instance is on
: is desired, since each instance on this cpu draws from
: the same stream
erand = exprand(1)
VERBATIM
}
ENDVERBATIM
:erand = value :This line must have been a mistake in Hay et al.'s code, it would basically set the return value to a non-initialized double value.
:The reason it sometimes works could be that the memory allocated for the non-initialized happened to contain the random value
:previously generated. However, here we commented this line out.
}
PROCEDURE setVec() { : Sets the times of firing of each synapse. This should be done only once for each ProbAMPANMDA2group,
: before the running of the simulation, and the underlying vector should be untouched after that.
VERBATIM
void** vv;
vv = (void**)(&space);
*vv = (void*)0;
if (ifarg(1)) {
*vv = vector_arg(1);
Nsyns = vector_capacity(*vv)/3;
}
ENDVERBATIM
}
PROCEDURE printVec() { : Prints the previous times of firing of each synapse.
VERBATIM
void** vv = (void**)(&space);
double *x;
int nx = vector_instance_px(*vv, &x);
int i1;
for (i1=0;i1<Nsyns;i1++) {
printf("tsyns[%i] = %g, Pv[%i] = %g, u[%i] = %g\n", i1, x[i1], i1, x[i1+(nx/3)], i1, x[i1+2*(nx/3)]);
}
ENDVERBATIM
}
PROCEDURE setVec2() { : Sets the IDs of the synapses to fire
VERBATIM
void** vv;
vv = (void**)(&space2);
*vv = (void*)0;
if (ifarg(1)) {
*vv = vector_arg(1);
Nevents = vector_capacity(*vv);
}
ENDVERBATIM
}
PROCEDURE printVec2() { : Prints the previous times of firing of each synapse.
VERBATIM
void** vv = (void**)(&space2);
double *x;
int nx = vector_instance_px(*vv, &x);
int i1;
for (i1=0;i1<Nevents;i1++) {
printf("%g ", x[i1]);
if (i1%100==99)
printf("\n");
}
ENDVERBATIM
}