glubes2.mod

TITLE 2D diffusion with absorbing boundary
COMMENT
Author: Elena Saftenku, 2003
ENDCOMMENT
NEURON{
POINT_PROCESS GrC_Glubes2
RANGE    glu,rPSD,rabs,nu, gluspill,gludir,Rmf
RANGE Deff,meandist,rabs 
RANGE inclugludir,inclugluspill, Popeak,alpha,Podir,Pospill,Pototal, Podir1 
RANGE tm1, td1, ts1
}
UNITS{
(molar)=(1/liter)
(mM)=(millimolar)
(um)=(micron)
(nA)=(nanoamp)
}
CONSTANT {
PI=3.1415927
}
PARAMETER { 
alpha=1 : extracellular volume fraction
Deff=0.2 (um2/ms) : effective difusion coefficient
nu=0.33(1/um2)  :   density of release sites
rabs= 4.1 (um) : radius of absorbing boundary
c0cleft = 8.769 (mM): initial [glu] in the cleft after vesicle release
rPSD=0.11 (um): radius of postsynaptic density
meandist=0.23 (um): minimal limit of spillover glutamate integration
Rmf=2.8(um) : radius of mossy fiber
Popeak=0.634 : adjusted peak open probability of AMPA receptors
inclugludir=1 : inclusion of direct component
inclugluspill=1: inclusion of spillover component
tm1= 0: 0.09 (ms), shift of experimental mEPSC
td1= 0 : 0.16(ms), shift of experimental direct EPSC
ts1= 0 : 0.16 (ms), shift of experimental spillover EPSC 
}
VERBATIM
static int i;
static double l[50000];
extern float bessj1(float);
ENDVERBATIM
ASSIGNED{
Podir
Podir1
Pospill 
Pototal
tx1(ms)
gludir (mM)
gluspill(mM)
glu (mM)
sum (um)
sum0 (um)
sum1(um2)
sum01(um2)
}
INITIAL {
tx1=10000000
glu=0 
gludir=0
gluspill=0
}
BREAKPOINT
{
at_time(tx1)
if (t<=tx1){
gludir=0
gluspill=0
glu=0
Podir=0
Podir1=0
Pospill=0
Pototal=0
}
if(t>tx1) {
VERBATIM
l[0]=0;
l[1]=2.4048;l[2]=5.5201;l[3]=8.6535;
sum=0; i=1; 
do 
{if (i>=4) 
l[i]=PI*(4*i-1)/4;
sum0=sum;
sum =sum+bessj1((l[i]/rabs)*rPSD)/((l[i]/rabs)*bessj1(l[i])*bessj1(l[i]))
* exp((l[i]/rabs)*(l[i]/rabs)*Deff*(tx1-t));
 i++; }
while (fabs(sum-sum0)>=0.01);

ENDVERBATIM
 gludir= c0cleft*2*rPSD*sum/(rabs*rabs)
if (gludir>c0cleft) {gludir=c0cleft}
:printf("sum= %f\n",sum)

VERBATIM
sum1=0; i=1;
do
{if (i>=4) 
l[i]=PI*(4*i-1)/4;
sum01=sum1;
sum1=sum1+(Rmf*bessj1((l[i]/rabs)*Rmf)-meandist 
* bessj1((l[i]/rabs) *meandist))/
((l[i]/rabs)*bessj1(l[i])*bessj1(l[i]))*exp((l[i]/rabs)*(l[i]/rabs)
*Deff*(tx1-t));
i++;}
while (fabs(sum1-sum01)>=0.0001);
ENDVERBATIM
gluspill=2*PI*nu*c0cleft*rPSD*rPSD*sum1/(rabs*rabs)
glu= inclugludir*gludir  +inclugluspill*gluspill

: Experimental waveforms
Podir=(0.94*exp((tx1-td1-t)/0.37(ms))+0.06*exp((tx1-td1-t)/2.2(ms))
  -exp((tx1-td1-t)/0.199(ms)))/0.249*(0.43/0.484)*Popeak :direct EPSC
Podir1=(0.94*exp((tx1-tm1-t)/0.3(ms))+0.06*exp((tx1-tm1-t)/3.1(ms))
  -exp((tx1-tm1-t)/0.12(ms)))/0.35*Popeak :mEPSC
Pospill=(0.39*exp((tx1-ts1-t)/2.0(ms))+0.61*exp((tx1-ts1-t)/9.1(ms))-
 exp((tx1-ts1-t)/0.44(ms)))/0.682*(0.125/0.484)*Popeak :spillover EPSC
Pototal=Podir+Pospill
 }
  }
NET_RECEIVE (weight,tsyn (ms))
{
tx1=t 
}