Axon-somatic back-propagation in a detailed model of cat spinal motoneuron (Balbi et al, 2015)

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Accession:180370
Morphologically detailed conductance-based models of cat spinal alpha motoneurons have been developed, with the aim to reproduce and clarify some aspects of the electrophysiological behavior of the antidromic axon-somatic spike propagation. Fourteen 3D morphologically detailed somata and dendrites of cat spinal alpha motoneurons have been imported from an open-access web-based database of neuronal morphologies, NeuroMorpho.org, and instantiated in neurocomputational models.
Reference:
1 . Balbi P, Martinoia S, Massobrio P (2015) Axon-somatic back-propagation in detailed models of spinal alpha motoneurons. Front Comput Neurosci 9:15 [PubMed]
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Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism: Spinal motoneuron;
Cell Type(s): Spinal cord lumbar motor neuron alpha ACh cell;
Channel(s): I Na,p; I Na,t; I K; I h; I K,Ca; I Calcium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s):
Implementer(s): Balbi, Pietro [piero.balbi at fsm.it];
Search NeuronDB for information about:  Spinal cord lumbar motor neuron alpha ACh cell; I Na,p; I Na,t; I K; I h; I K,Ca; I Calcium;
soma[0] distance(0,0)

objref secref, secref2, term, sl, secmed, box3, box4, gr3
strdef lab
strdef med_dend

proc ca_chan() {  // attribuisce i valori delle conduttanze di L_Ca e kca2 
    forsec secmed {
	        insert L_Ca
	              gcabar_L_Ca = $1
	              tau_m_L_Ca=60
	              theta_m_L_Ca = -40
            insert kca2
	              g_kca2 = $2
	              depth2_kca2 = 200
	              taur2_kca2 = 60
            
            // subroutine per ridurre le zone di PIC dendritica
            
            flag1 = 0
            loc1 = 0
            loc2 = 1
            if (distance(0)<min_d) { flag1 = 2 }
            
            for(x,0) {
            	if ((flag1==0)&&(distance(x)>max_d)) {
            		loc1=x
            		flag1=1
            	}
            	if ((flag1==2)&&(distance(x)>min_d)) {
            		loc1=x
            		flag1=3
            	}
            	if ((flag1==3)&&(distance(x)>max_d)) {
            		loc2=x
            		flag1=4
            	}
            }

            //   |  ----|----  
            if (flag1==1) { 
            	gcabar_L_Ca(0:loc1)=$1:$1
            	gcabar_L_Ca(loc1:1)=0:0
            	g_kca2(0:loc1)=$2:$2
            	g_kca2(loc1:1)=0:0
            }
            
            //   ----|----  |	
            if (flag1==3) { 
            	gcabar_L_Ca(0:loc1)=0:0
            	gcabar_L_Ca(loc1:1)=$1:$1
            	g_kca2(0:loc1)=0:0
            	g_kca2(loc1:1)=$2:$2
            }
	        
            //   --|----|--	
            if (flag1==4) {
            	gcabar_L_Ca(0:loc1)=0:0
            	gcabar_L_Ca(loc1:loc2)=$1:$1
            	gcabar_L_Ca(loc2:1)=0:0
            	g_kca2(0:loc1)=0:0
            	g_kca2(loc1:loc2)=$2:$2
            	g_kca2(loc2:1)=0:0
            }
            
            // |  --------  |

    }

	// subroutine per il calcolo del punto medio (uno) dei canali del calcio dendritici
	// med_dend stringa per nome sezione, secref2 riferimento alla sezione
	// (utilizzato dal grafico delle variabili di attivazione)
	
	med_d = (min_d + max_d)/2
	in = 0

	forsec secmed for(x,0) {
		if ((distance(x)>=(med_d-5))&&(distance(x)<=(med_d+5))&&(in==0)) {
			secref2 = new SectionRef()
			index = x
			sprint(med_dend,"%s",secname())	
			in = in + 1
		}
	}
}

proc soma_mech() {
	forsec "soma" {
		Ra=70
		cm=1
		insert pas
			g_pas=0.0044
			e_pas=-72
		insert na3rp
			gbar_na3rp=0.015 // original value 0.044
			sh_na3rp=0      // original value 5
			ar_na3rp=0.4
		insert naps
			gbar_naps=0.002  // original value 0.00044
			sh_naps=15		 // original value 0
			ar_naps=0.4
		insert kdrRL
			gMax_kdrRL=0.035  // original value 0.07
		insert gh
			ghbar_gh = 0.0001325
			half_gh=-75
		insert mAHP
			gcamax_mAHP = 8e-06
			gkcamax_mAHP = 0.01 // original value 0.0076
			taur_mAHP = 56.6666666666667
		insert extracellular xraxial=1e9 xg=1e10 xc=0
	}
}

proc dend_mech() {
	forsec "dend" {
		Ra=70
		cm=1
                
        nseg = 2*int(L/40)+1 // L/nseg max 20 micron

		insert pas
			g_pas = 7.22e-05
			e_pas = -72
		insert na3rp
			gbar_na3rp = 1.5e-4
			sh_na3rp = 0	// original value 5
			ar_na3rp = 0.4
		insert naps
			gbar_naps = 1.5e-5
			sh_naps = 15	// original value 0
			ar_naps = 0.4
		insert kdrRL
			gMax_kdrRL = 3e-4
		insert gh
			ghbar_gh = 1.325e-4
			half_gh = -75
		insert extracellular xraxial=1e9 xg=1e10 xc=0
	}
}

proc prim_mech() {
	sl=new SectionList() // variabile lista dei tronchi dendritici primari
	soma[0] sl.children() // memorizza i tronchi dendritici primari (più soma[1])
	forsec sl {
		ifsec "soma" {
			sl.remove()  // elimina soma[1] dalla lista dei dendriti primari
		
			print "tronchi dendritici primari: sl"
			sl.printnames()  // flag per debugging
			print ""
		}
	}
		
	forsec sl { // valori particolari per i tronchi dendritici primari, poi modificati
			gbar_na3rp = 0.015  // valore originario 0.044
			gbar_naps = 0.002   // valore originario 0.00044
			gMax_kdrRL = 0.035    // valore originario 0.07
		insert mAHP
			gcamax_mAHP = 8e-06
			gkcamax_mAHP = 0.01  // original value 0.0076
			taur_mAHP = 56.6666666666667

	}
	
	term=new Vector() //  vettore per le distanze dal soma dei rami terminali
	
	forsec "dend" {
		secref=new SectionRef()
		if (secref.nchild==0) {  // ramificazioni terminali, prive di children
	
			term.append(distance(1))
		}
	}

	// subroutine per limitare la distribuzione dei canali ionici sui dendriti primari
	// (simile a soma) al 10% della lunghezza media dei dendriti
	
	print "\nRiduzione dendriti primari: "
	
	forsec sl {
		ind = 0
		for(x,0) {
			if ((distance(x)>=(term.mean()*0.1))&&(ind==0)) {
				gbar_na3rp(0:x) = 0.015:0.015		//
				gbar_na3rp(x:1) = 1.5e-4:1.5e-4
				gbar_naps(0:x) = 0.002:0.002  	//
				gbar_naps(x:1) = 1.5e-5:1.5e-5
				gMax_kdrRL(0:x) = 0.035:0.035	//
				gMax_kdrRL(x:1) = 3e-4:3e-4
				gcamax_mAHP(0:x) = 8e-6:8e-6
				gcamax_mAHP(x:1) = 0:0
				gkcamax_mAHP(0:x) = 0.01:0.01		//
				gkcamax_mAHP(x:1) = 0:0
				ind = 1
				print secname(), "(", x, ")"
			}
		}
	}
	
}

// routine per l'inserimento dei canali del calcio nei dendriti medi

proc med_mech() {
	min_d=$1*term.mean()
	max_d=$2*term.mean()
	print "\nmin L_Ca dist.= ", min_d  // distanza minima da soma dei rami 'medi'
	print "max L_Ca dist.= ", max_d  // distanza massima da soma dei rami 'medi'
	print ""

	secmed=new SectionList()
	forsec "dend" {
	       flag = 0
	       for(x) if((flag==0)&&((distance(x)>=min_d)&&(distance(x)<=max_d))) {
	              flag = flag + 1
                  secmed.append
                  }
    }

    ca_chan(2.8e-4,1.6e-4)
}

// display graphics

proc disp1() {

	box3 = new VBox()
	box3.intercept(1)
	gr1 = new Graph()
	gr1.size(0,300,-80,40)
	gr1.addvar("soma.v(.5)")
	graphList[0].append(gr1)
	gr2 = new Graph()
	gr2.size(0,300,-80,40)
	sprint(lab,"%s.v(%g)",med_dend,index)
	gr2.label(.5,1)
	gr2.addvar(lab,"secref2.sec.v(index)",3,1)
	graphList[0].append(gr2)
	box3.intercept(0)
	box3.map("Voltage",850,25,350,600)

	box4 = new VBox()
	box4.intercept(1)
	gr3 = new Graph()
	gr3.size(0,300,0,1)
	sprint(lab,"%s.m_L_Ca(%g)",med_dend,index)
	gr3.label(.5,1)
	gr3.addvar(lab,"secref2.sec.m_L_Ca(index)",3,1)
	sprint(lab,"%s.n_kca2(%g)",med_dend,index)
	gr3.addvar(lab,"secref2.sec.n_kca2(index)",1,1)
	graphList[0].append(gr3)
	box4.intercept(0)
	box4.map("States",500,400,350,300)
}

soma_mech()          // inserisce meccanismi in soma
dend_mech()          // inserisce meccanismi nei dendriti
prim_mech()          // meccanismi nei dendriti primari
med_mech(0.30,0.60)  // conduttanza dei canali del calcio dendritici a distanza media da soma

// disp1()              // grafici di base

print "\nca_chan() varia le conduttanze di L_Ca ($1) e kca2 ($2)"
print " valori di base: 2.8e-4 e 1.6e-4\n"

// parametri vari per files .mod

tmin_kdrRL = 0.8
taumax_kdrRL = 20
qinf_na3rp = 4.8
thinf_na3rp = -50.5
Rd_na3rp = 0.06
qd_na3rp = 1.3
qg_na3rp = 1.3
thi1_na3rp = -35
thi2_na3rp = -35
vslope_naps = 5
V0 = -3.88888888888889