Ribbon Synapse (Sikora et al 2005)

 Download zip file   Auto-launch 
Help downloading and running models
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;
TITLE decay of submembrane calcium concentration
:
: 2. Simple first-order decay or buffering:
:
:       Cai + B <-> ...
:
:   which can be written as:
:
:       dCai/dt = (cainf - Cai) / taur
:
:   where cainf is the equilibrium intracellular calcium value (usually
:   in the range of 200-300 nM) and taur is the time constant of calcium 
:   removal.  The dynamics of submembranal calcium is usually thought to
:   be relatively fast, in the 1-10 millisecond range (see Blaustein, 
:   TINS, 11: 438, 1988).
:
: All variables are range variables
:
: Written by Alain Destexhe, Salk Institute, Nov 12, 1992
: Modified by TJ Velte, Univ of Minnesota, May 6, 1995

INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}

NEURON {
	SUFFIX cas
	USEION ca READ ica, cai WRITE cai
	RANGE kd,cainf,taur
}

UNITS {
	(molar) = (1/liter)			: moles do not appear in units
	(mM)	= (millimolar)
	(um)	= (micron)
	(mA)	= (milliamp)
	(msM)	= (ms mM)
}

CONSTANT {
	FARADAY = 96489		(coul)		: moles do not appear in units
}

PARAMETER {
	diam (micron)
	taur	= 1.5	(ms)		: remove first-order decay
	cainf	= 0.0001 (mM)
	kd	= 0.0011	(mM)
}

STATE {
	cai		(mM) 
}

INITIAL {
	cai = kd
}

ASSIGNED {
	ica		(mA/cm2)
	drive_channel	(mM/ms)
}
	
BREAKPOINT {
	SOLVE state METHOD derivimplicit
					: printf("diam=%g\n", diam)
}

DERIVATIVE state { 

	drive_channel = - ( (2 * ica) / (FARADAY * diam) ) 

	if (drive_channel <= 0.) { drive_channel = 0. }	: cannot pump inward

	cai' = drive_channel - ( (cai - cainf) /  taur )
}


Loading data, please wait...