LTP in cerebellar mossy fiber-granule cell synapses (Saftenku 2002)

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Accession:51196
We simulated synaptic transmission and modified a simple model of long-term potentiation (LTP) and long-term depression (LTD) in order to describe long-term plasticity related changes in cerebellar mossy fiber-granule cell synapses. In our model, protein autophosphorylation, leading to the maintenance of long-term plasticity, is controlled by Ca2+ entry through the NMDA receptor channels. The observed nonlinearity in the development of long-term changes of EPSP in granule cells is explained by the difference in the rate constants of two independent autocatalytic processes.
Reference:
1 . Saftenku EE (2002) A simplified model of long-term plasticity in cerebellar mossy fiber-granule cell synapses. Neurophysiology/Neirofiziologiya 34:216-218
Model Information (Click on a link to find other models with that property)
Model Type: Synapse;
Brain Region(s)/Organism:
Cell Type(s):
Channel(s):
Gap Junctions:
Receptor(s): AMPA; NMDA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Simplified Models; Long-term Synaptic Plasticity; Maintenance;
Implementer(s): Saftenku, Elena [esaft at biph.kiev.ua];
Search NeuronDB for information about:  AMPA; NMDA;
TITLE glutamate concentration and short-term plasticity
COMMENT
Author: Elena Saftenku, 2001
ENDCOMMENT
NEURON{
POINT_PROCESS GrC_Glu1
RANGE conccap,glu
RANGE taurec,taufacil,tauin, u0, usr 
}
UNITS{
(molar)=(1/liter)
(mM)=(millimolar)
}
PARAMETER {
taurec=800 (ms): time constant of recovery from depletion
tauin=3 (ms): decay constant of transmitter
taufacil=20(ms): time constant of facilitation
usr=0.1 : the use of synaptic resources by each spike
u0=0 <0,1> : initial value of the facilitated usr
 }
ASSIGNED{
tx1(ms): time of spike
conccap :release probability
conc01(mM): resting concentration at the beginning of the next spike
conc02(mM)
conc03(mM)
vspr :auxiliary variable
glu (mM): glutamate concentration
glu1 (mM): separate exponential terms of glu
glu2 (mM)
glu3 (mM)
}
INITIAL {
tx1=10000000
conc01=0
conc02=0
conc03=0

conccap=0
glu=0
}
BEFORE BREAKPOINT
{ 
if (t<tx1){
glu=0
glu1=0
glu2=0
glu3=0
}
if(t>=tx1) {
glu1= conccap*(2.88(mM)+conc01)*exp((tx1-t)/0.05(ms))
glu2=conccap*(0.2(mM)+conc02)*exp((tx1-t)/0.5(ms))
glu3=conccap*(0.04(mM)+conc03)*exp((tx1-t)/1.7(ms))
glu=glu1+glu2+glu3
}
}
NET_RECEIVE (weight,Eav,R, u,tsyn (ms))
{
INITIAL
{
R=1
Eav=0
u=u0
tsyn=t}
vspr=((1-R-Eav)/taurec+(R-1)/tauin)/(1/tauin-1/taurec)
R=1+exp((tsyn-t)/taurec)*vspr+exp((tsyn-t)/tauin)*(R-1-vspr)
Eav=Eav*exp((tsyn-t)/tauin)
if (taufacil>0){
u=u*exp((tsyn-t)/taufacil)
}else {
u=usr
}
if (taufacil>0) {
u = u+usr*(1-u)
}
Eav=Eav+R*u
conccap=(u*R/usr)*weight
R=R-u*R
tsyn=t
conc01=glu1
conc02=glu2
conc03=glu3
tx1=t 
}


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