Coincident signals in Olfactory Bulb Granule Cell spines (Aghvami et al 2019)

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Accession:244687
"In the mammalian olfactory bulb, the inhibitory axonless granule cells (GCs) feature reciprocal synapses that interconnect them with the principal neurons of the bulb, mitral, and tufted cells. These synapses are located within large excitable spines that can generate local action potentials (APs) upon synaptic input (“spine spike”). Moreover, GCs can fire global APs that propagate throughout the dendrite. Strikingly, local postsynaptic Ca2+ entry summates mostly linearly with Ca2+ entry due to coincident global APs generated by glomerular stimulation, although some underlying conductances should be inactivated. We investigated this phenomenon by constructing a compartmental GC model to simulate the pairing of local and global signals as a function of their temporal separation ?t. These simulations yield strongly sublinear summation of spine Ca2+ entry for the case of perfect coincidence ?t = 0 ms. ..."
Reference:
1 . Aghvami SS, Müller M, Araabi BN, Egger V (2019) Coincidence Detection within the Excitable Rat Olfactory Bulb Granule Cell Spines. J Neurosci 39:584-595 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Dendrite; Channel/Receptor; Synapse;
Brain Region(s)/Organism: Olfactory bulb;
Cell Type(s): Olfactory bulb main interneuron granule MC GABA cell; Olfactory bulb main interneuron granule TC GABA cell;
Channel(s): Ca pump; I Calcium; I K; I Sodium;
Gap Junctions:
Receptor(s): NMDA; AMPA;
Gene(s):
Transmitter(s): Glutamate;
Simulation Environment: NEURON; Python;
Model Concept(s): Active Dendrites; Calcium dynamics; Coincidence Detection;
Implementer(s): Aghvami, S. Sara [ssa.aghvami at gmail.com];
Search NeuronDB for information about:  Olfactory bulb main interneuron granule MC GABA cell; Olfactory bulb main interneuron granule TC GABA cell; AMPA; NMDA; I K; I Sodium; I Calcium; Ca pump; Glutamate;
TITLE n-calcium channel
: n-type calcium channel


UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)

	FARADAY = 96520 (coul)
	R = 8.3134 (joule/degC)
	KTOMV = .0853 (mV/degC)
}

PARAMETER {
	v (mV)
	celsius 		(degC)
	gcanbar=.0003 (mho/cm2)
	ki=.001 (mM)
	cai=50.e-6 (mM)
	cao = 2  (mM)
	q10=5
	mmin = 0.2
	hmin = 3
	a0m =0.03
	zetam = 2
	vhalfm = -14
	gmm=0.1	
}


NEURON {
	SUFFIX canhem
	USEION ca READ cai,cao WRITE ica
        RANGE gcanbar, ica, gcan,q10,a0m       
        GLOBAL hinf,minf,taum,tauh
}

STATE {
	m h 
}

ASSIGNED {
	ica (mA/cm2)
        gcan  (mho/cm2) 
        minf
        hinf
        taum
        tauh
}

INITIAL {
        rates(v)
        m = minf
        h = hinf
}

BREAKPOINT {
	SOLVE states METHOD cnexp
	gcan = gcanbar*m*m*h*h2(cai)
	ica = gcan*ghk(v,cai,cao)

}

UNITSOFF
FUNCTION h2(cai(mM)) {
	h2 = ki/(ki+cai)
}


FUNCTION ghk(v(mV), ci(mM), co(mM)) (mV) {
        LOCAL nu,f

        f = KTF(celsius)/2
        nu = v/f
        ghk=-f*(1. - (ci/co)*exp(nu))*efun(nu)
}

FUNCTION KTF(celsius (degC)) (mV) {
        KTF = ((25./293.15)*(celsius + 273.15))
}


FUNCTION efun(z) {
	if (fabs(z) < 1e-4) {
		efun = 1 - z/2
	}else{
		efun = z/(exp(z) - 1)
	}
}

FUNCTION alph(v(mV)) {
	alph = 1.6e-4*exp(-v/48.4)
}

FUNCTION beth(v(mV)) {
	beth = 1/(exp((-v+39.0)/10.)+1.)
}

FUNCTION alpm(v(mV)) {
	alpm = 0.1967*(-1.0*v+19.88)/(exp((-1.0*v+19.88)/10.0)-1.0)
}

FUNCTION betm(v(mV)) {
	betm = 0.046*exp(-v/20.73)
}

FUNCTION alpmt(v(mV)) {
  alpmt = exp(0.0378*zetam*(v-vhalfm)) 
}

FUNCTION betmt(v(mV)) {
  betmt = exp(0.0378*zetam*gmm*(v-vhalfm)) 
}

UNITSON

DERIVATIVE states {     : exact when v held constant; integrates over dt step
        rates(v)
        m' = (minf - m)/taum
        h' = (hinf - h)/tauh
}

PROCEDURE rates(v (mV)) { :callable from hoc
        LOCAL a, b, qt
        qt=q10^((celsius-25)/10)
        a = alpm(v)
        b = 1/(a + betm(v))
        minf = a*b
	taum = betmt(v)/(qt*a0m*(1+alpmt(v)))
	if (taum<mmin/qt) {taum=mmin/qt}
        a = alph(v)
        b = 1/(a + beth(v))
        hinf = a*b
:	tauh=b/qt
	tauh= 80
	if (tauh<hmin) {tauh=hmin}
}







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