A network model of the vertebrate retina (Publio et al. 2009)

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Accession:124063
In this work, we use a minimal conductance-based model of the ON rod pathways in the vertebrate retina to study the effects of electrical synaptic coupling via gap junctions among rods and among AII amacrine cells on the dynamic range of the retina. The model is also used to study the effects of the maximum conductance of rod hyperpolarization activated current Ih on the dynamic range of the retina, allowing a study of the interrelations between this intrinsic membrane parameter with those two retina connectivity characteristics.
Reference:
1 . Publio R, Oliveira RF, Roque AC (2009) A computational study on the role of gap junctions and rod Ih conductance in the enhancement of the dynamic range of the retina. PLoS One 4:e6970 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network;
Brain Region(s)/Organism:
Cell Type(s): Retina ganglion GLU cell; Retina photoreceptor cone GLU cell; Retina bipolar GLU cell;
Channel(s):
Gap Junctions: Gap junctions;
Receptor(s):
Gene(s):
Transmitter(s): Glutamate;
Simulation Environment: NEURON;
Model Concept(s): Sensory processing;
Implementer(s): Publio, Rodrigo [publio at oist.jp];
Search NeuronDB for information about:  Retina ganglion GLU cell; Retina photoreceptor cone GLU cell; Retina bipolar GLU cell; Glutamate;
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PublioEtAl2009
README.html
A2hh_k.mod
A2hh_na.mod
Bip_Ca.mod
Bip_Cad.mod
Bip_ih.mod
Bip_Ka.mod
Bip_Kv.mod
Cone_CPR.mod
Cone_ih.mod
Cone_Kv.mod
Ganglion_hh.mod *
gap.mod
IinjLT.mod
IinjLT_cone.mod
IinjLTDim.mod *
Rod_Ca.mod
Rod_Cad.mod
Rod_Clca.mod
Rod_ih.mod
Rod_Kca.mod
Rod_Kv.mod
Rod_Kx.mod
Rod_leak.mod
syn_bip_gan.mod
syn_rod_bip.mod
A2.tem
Bip.tem
Cone.tem
createcells.hoc
Ganglion.tem
gap.hoc *
init.hoc
mosinit.hoc *
netconnection.hoc
parameters.hoc
Rod.tem
screenshot1.jpg
screenshot2.jpg
session.ses
                            
TITLE decay of internal calcium concentration
:
: Internal calcium concentration due to calcium currents and pump.
: Differential equations.
:
: Simple model of ATPase pump with 3 kinetic constants (Destexhe 92)
:     Cai + P <-> CaP -> Cao + P  (k1,k2,k3)
: A Michaelis-Menten approximation is assumed, which reduces the complexity
: of the system to 2 parameters: 
:       kt = <tot enzyme concentration> * k3  -> TIME CONSTANT OF THE PUMP
:	kd = k2/k1 (dissociation constant)    -> EQUILIBRIUM CALCIUM VALUE
: The values of these parameters are chosen assuming a high affinity of 
: the pump to calcium and a low transport capacity (cfr. Blaustein, 
: TINS, 11: 438, 1988, and references therein).  
:
: Units checked using "modlunit" -> factor 10000 needed in ca entry
:
: VERSION OF PUMP + DECAY (decay can be viewed as simplified buffering)
:
: All variables are range variables
:
:
: This mechanism was published in:  Destexhe, A. Babloyantz, A. and 
: Sejnowski, TJ.  Ionic mechanisms for intrinsic slow oscillations in
: thalamic relay neurons. Biophys. J. 65: 1538-1552, 1993)
:
: Written by Alain Destexhe, Salk Institute, Nov 12, 1992
:
: This file was modified by Yiota Poirazi (poirazi@LNC.usc.edu) on April 18, 2001 to account for the sharp
: Ca++ spike repolarization observed in: Golding, N. Jung H-Y., Mickus T. and Spruston N
: "Dendritic Calcium Spike Initiation and Repolarization are controlled by distinct potassium channel
: subtypes in CA1 pyramidal neurons". J. of Neuroscience 19(20) 8789-8798, 1999.
:
:  factor 10000 is replaced by 10000/18 needed in ca entry
:  taur --rate of calcium removal-- is replaced by taur*7 (7 times faster) 

: Xiaodong Liu 2003-12-08 Calcium Dynamics for Rod inner segment

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

NEURON {
	SUFFIX Cad
	USEION Ca READ iCa, Cai WRITE Cai,Cao VALENCE 2	
        RANGE Ca, depth, Cainf, taur, entryF
}

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


PARAMETER {
	depth	= 10	(um)		: depth of shell
	taur	= 20	(ms)		: rate of calcium removal
	Cainf	= 5e-5  (mM)		: 2uM
	Cai		(mM)
	Cao     = 2     (mM)
	entryF  = 1
}

STATE {
	Ca		(mM) 
}

INITIAL {
	Ca = Cainf
	Cao=2
	
}

ASSIGNED {
	iCa		(mA/cm2)
	drive_channel	(mM/ms)
}
	
BREAKPOINT {
	SOLVE state METHOD derivimplicit
}

DERIVATIVE state { 

	drive_channel =  - (10000) * iCa / (2 * FARADAY * depth)
	if (drive_channel <= 0.) { drive_channel = 0.  }   : cannot pump inward 
         
	:ca' = drive_channel + (cainf-ca)/taur
        :Ca' = drive_channel/18 + (Cainf -Ca)/taur*7
	Ca' = entryF*drive_channel/2 + (Cainf-Ca)/taur
	
        Cai = Ca
	Cao=2 :mM
}

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