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]
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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
T-type Ca channel 
ca.mod to lead to thalamic ca current inspired by destexhe and huguenrd
Uses fixed eca instead of GHK eqn
changed from (AS Oct0899)
changed for use with Ri18  (B.Kampa 2005)
ENDCOMMENT

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

NEURON {
	SUFFIX it
	USEION ca READ eca WRITE ica
	RANGE m, h, gca, gbar
	RANGE minf, hinf, mtau, htau, inactF, actF
	GLOBAL  vshift,vmin,vmax, v12m, v12h, vwm, vwh, am, ah, vm1, vm2, vh1, vh2, wm1, wm2, wh1, wh2
}

PARAMETER {
	gbar = 0.0008 (mho/cm2)	: 0.12 mho/cm2
	vshift = 0	(mV)		: voltage shift (affects all)

	cao  = 2.5	(mM)	        : external ca concentration
	cai		(mM)
						 
	v 		(mV)
	dt		(ms)
	celsius		(degC)
	vmin = -120	(mV)
	vmax = 100	(mV)

	v12m=50         	(mV)
	v12h=78         	(mV)
	vwm =7.4         	(mV)
	vwh=5.0         	(mV)
	am=3         	(mV)
	ah=85         	(mV)
	vm1=25         	(mV)
	vm2=100         	(mV)
	vh1=46         	(mV)
	vh2=405         	(mV)
	wm1=20         	(mV)
	wm2=15         	(mV)
	wh1=4         	(mV)
	wh2=50         	(mV)


}


UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
	(pS) = (picosiemens)
	(um) = (micron)
	FARADAY = (faraday) (coulomb)
	R = (k-mole) (joule/degC)
	PI	= (pi) (1)
} 

ASSIGNED {
	ica 		(mA/cm2)
	gca		(pS/um2)
	eca		(mV)
	minf 		hinf
	mtau (ms)	htau (ms)
	tadj
}
 

STATE { m h }

INITIAL { 
	trates(v+vshift)
	m = minf
	h = hinf
}

BREAKPOINT {
        SOLVE states
        gca = gbar*m*m*h
	ica = gca * (v - eca)
} 

LOCAL mexp, hexp

PROCEDURE states() {
        trates(v+vshift)      
        m = m + mexp*(minf-m)
        h = h + hexp*(hinf-h)
	VERBATIM
	return 0;
	ENDVERBATIM
}


PROCEDURE trates(v) {  
                      
        LOCAL tinc
        TABLE minf, mexp, hinf, hexp
	DEPEND dt	
	FROM vmin TO vmax WITH 199

	rates(v): not consistently executed from here if usetable == 1

        tinc = -dt 

        mexp = 1 - exp(tinc/mtau)
        hexp = 1 - exp(tinc/htau)
}


PROCEDURE rates(v_) {  
        LOCAL  a, b

	minf = 1.0 / ( 1 + exp(-(v_+v12m)/vwm) )
	hinf = 1.0 / ( 1 + exp((v_+v12h)/vwh) )

	mtau = ( am + 1.0 / ( exp((v_+vm1)/wm1) + exp(-(v_+vm2)/wm2) ) ) 
	htau = ( ah + 1.0 / ( exp((v_+vh1)/wh1) + exp(-(v_+vh2)/wh2) ) ) 
}