Ribbon Synapse (Sikora et al 2005)

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Accession:50997
A model of the ribbon synapse was developed to replicate both pre- and postsynaptic functions of this glutamatergic juncture. The presynaptic portion of the model is rich in anatomical and physiological detail and includes multiple release sites for each ribbon based on anatomical studies of presynaptic terminals, presynaptic voltage at the terminal, the activation of voltage-gated calcium channels and a calcium-dependent release mechanism whose rate varies as a function of the calcium concentration that is monitored at two different sites which control both an ultrafast, docked pool of vesicles and a release ready pool of tethered vesicles. See paper for more and details.
Reference:
1 . Sikora MA, Gottesman J, Miller RF (2005) A computational model of the ribbon synapse. J Neurosci Methods 145:47-61 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Synapse;
Brain Region(s)/Organism:
Cell Type(s): Retina ganglion GLU cell; Retina bipolar GLU cell;
Channel(s): I L high threshold;
Gap Junctions:
Receptor(s): AMPA; NMDA;
Gene(s):
Transmitter(s): Glutamate;
Simulation Environment: NEURON;
Model Concept(s): Intrinsic plasticity; Calcium dynamics;
Implementer(s): Sikora, Michael [Sikora at umn.edu];
Search NeuronDB for information about:  Retina ganglion GLU cell; Retina bipolar GLU cell; AMPA; NMDA; I L high threshold; Glutamate;
load_file("nrngui.hoc")
load_proc ("nrnmainmenu")
create soma, bp, bp2
soma {L=25 diam=25 nseg=2}
bp {L=10 diam=10 nseg=1}
bp2 {L=10 diam=10 nseg=1}
// Pre synaptic mechanisms (L channel and Voltage Clamp)
access bp
insert cad
insert gfbp

access bp2
insert cad
insert gfbp



objectvar synapse[50]
access soma
insert spike
gcabar_spike =  0.0015
gkbar_spike =   0.018
gabar_spike =   0.054
gkcbar_spike =  0.000065
gnabar_spike =  0.10 
insert cas
for i=0, 49{
synapse[i] = new ribbon_ca(0.5)
setpointer synapse[i].preCA1,bp.cai(0.5)
setpointer synapse[i].preCA2,bp2.cai(0.5)
}
objectvar somaclamp
somaclamp=new VClamp(0.5)


soma{ 
mod_modulator = 0
ena=35
ek=-75 
cao=1.8
cai=.0001
insert pas
g_pas= 1/70000
Ra=110
global_ra=110
e_pas=-65
}
// Pre synaptic mechanisms (L channel and Voltage Clamp)
access bp // Full RRP
insert pas
g_pas= 1/70000
Ra=110
global_ra=110
e_pas=-65
depth_cad = 0.025
taur_cad=0.8
gcabar_gfbp =  0.0012
objectvar bpclamp
bpclamp = new VClamp2(0.5)

access bp2 // Less than Full RRP
insert pas
g_pas= 1/70000
Ra=110
global_ra=110
e_pas=-65
depth_cad = 0.05
taur_cad=0.18
gcabar_gfbp =  0.0012
objectvar bpclamp2
bpclamp2 = new VClamp2(0.5)

RIN = 0.125
TR = 0.8
TR2 = 0.18
MAXRVP=5
GCABP = 0.0016
GCABP2 = 0.0016
dcad1 = 0.025
dcad2 = 0.050
// RS = 2.84985

proc set_stim(){
for i = 0, 49 {
synapse[i].rate_constantIN = RIN
synapse[i].Max_RVP = MAXRVP
// synapse[i].S = RS
}
bp.taur_cad = TR
bp2.taur_cad = TR2
bp.gcabar_gfbp = GCABP
bp2.gcabar_gfbp = GCABP2
bp.depth_cad = dcad1
bp2.depth_cad = dcad2
}

objectvar vbox,vbox3, tempobj3

proc rate_panel(){
        vbox3 = new VBox()
        vbox3.intercept(1)

        xpanel("")
        xvalue("RC IN","RIN",1, "set_stim()")
        xvalue("Taur BP","TR",1, "set_stim()")
        xvalue("Taur BP-2","TR2",1, "set_stim()")
        xvalue("MAX RVP","MAXRVP",1, "set_stim()")
        xvalue("gcabar bp","GCABP",1, "set_stim()")
        xvalue("gcabar bp2","GCABP2",1, "set_stim()")
        xvalue("depth_cad bp","dcad1",1, "set_stim()")
        xvalue("depth_cad bp2","dcad2",1, "set_stim()")
//        xvalue("R&S rateout","RS",1, "set_stim()")

        xpanel()
        vbox3.intercept(0)
        vbox3.map
}


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