Nonlinear dendritic processing in barrel cortex spiny stellate neurons (Lavzin et al. 2012)

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Accession:146565
This is a multi-compartmental simulation of a spiny stellate neuron which is stimulated by a thalamocortical (TC) and cortico-cortical (CC) inputs. No other cells are explicitly modeled; the presynaptic network activation is represented by the number of active synapses. Preferred and non –preferred thalamic directions thus correspond to larder/smaller number of TC synapses. This simulation revealed that randomly activated synapses can cooperatively trigger global NMDA spikes, which involve participation of most of the dendritic tree. Surprisingly, we found that although the voltage profile of the cell was uniform, the calcium influx was restricted to ‘hot spots’ which correspond to synaptic clusters or large conductance synapses
Reference:
1 . Lavzin M, Rapoport S, Polsky A, Garion L, Schiller J (2012) Nonlinear dendritic processing determines angular tuning of barrel cortex neurons in vivo. Nature 490:397-401 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network; Neuron or other electrically excitable cell; Synapse; Dendrite;
Brain Region(s)/Organism:
Cell Type(s): Neocortex spiny stellate cell;
Channel(s): I Sodium; I Potassium; Ca pump;
Gap Junctions:
Receptor(s): GabaA; AMPA; NMDA;
Gene(s):
Transmitter(s): Gaba; Glutamate;
Simulation Environment: NEURON;
Model Concept(s): Active Dendrites; Detailed Neuronal Models; Synaptic Integration; Calcium dynamics; Direction Selectivity; Whisking;
Implementer(s): Polsky, Alon [alonpol at tx.technion.ac.il];
Search NeuronDB for information about:  GabaA; AMPA; NMDA; I Sodium; I Potassium; Ca pump; Gaba; Glutamate;
COMMENT
//****************************//
// Created by Alon Polsky 	//
//    apmega@yahoo.com		//
//		2010			//
//****************************//
ENDCOMMENT

TITLE NMDA synapse with depression

NEURON {
	POINT_PROCESS glutamate_old
	NONSPECIFIC_CURRENT inmda,iampa
	RANGE del,Tspike,Nspike
	RANGE e ,gampamax,gnmdamax,local_v,inmda,iampa
	RANGE decayampa,decaynmda,dampa,dnmda
	RANGE gnmda,gampa

	GLOBAL n, gama,tau_ampa,taudampa,taudnmda
	GLOBAL tau1,tau2

	:USEION canmda WRITE icanmda VALENCE 2
	USEION ca WRITE ica
	GLOBAL icaconst
}

UNITS {
	(nA) 	= (nanoamp)
	(mV)	= (millivolt)
	(nS) 	= (nanomho)
	(mM)    = (milli/liter)
        F	= 96480 (coul)
        R       = 8.314 (volt-coul/degC)
 	PI = (pi) (1)
	(mA) = (milliamp)
	(um) = (micron)

}

PARAMETER {
	icaconst =0.1
	gnmdamax=1	(nS)
	gampamax=1	(nS)
	e= 0.0	(mV)
	tau1=50	(ms)	
	tau2=2	(ms)	
	tau_ampa=1	(ms)	
	n=0.25 	(/mM)	
	gama=0.08 	(/mV) 
	dt (ms)
	v		(mV)
	del=30	(ms)
	Tspike=10	(ms)
	Nspike=1
 	decayampa=.5
	decaynmda=.5
	taudampa=200	(ms):tau decay
	taudnmda=200	(ms):tau decay
}

ASSIGNED {
	inmda		(nA)  
	iampa		(nA)  
	gnmda		(nS)
	local_v	(mV):local voltage
	:icanmda			(nA)
	ica			(nA)

}
STATE {
	A 		(nS)
	B 		(nS)
	gampa 	(nS)
	dampa
	dnmda
}

INITIAL {
      gnmda=0 
      gampa=0 
	A=0
	B=0
	dampa=1
	dnmda=1
	:icanmda=0
}    

BREAKPOINT {  
    
	LOCAL count
	SOLVE state METHOD cnexp
	FROM count=0 TO Nspike-1 {
		IF(at_time(count*Tspike+del)){
			state_discontinuity( A, A+ gnmdamax*(dnmda))
			state_discontinuity( B, B+ gnmdamax*(dnmda))
			state_discontinuity( gampa, gampa+ gampamax*dampa)
			state_discontinuity( dampa, dampa* decayampa)
			state_discontinuity( dnmda, dnmda* decaynmda)
		}
	}

	gnmda=(A-B)/(1+n*exp(-gama*v) )
	inmda =(1e-3)* gnmda  * (v-e)
	iampa= (1e-3)*gampa* (v- e)
	local_v=v
	:icanmda=inmda/10
	ica=inmda*0.1/(PI*diam)*icaconst
	inmda=inmda*.9

}

DERIVATIVE state {
	A'=-A/tau1
	B'=-B/tau2
	gampa'=-gampa/tau_ampa
	dampa'=(1-dampa)/taudampa
	dnmda'=(1-dnmda)/taudnmda
}

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