Olfactory Mitral cell: AP initiation modes (Chen et al 2002)

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The mitral cell primary dendrite plays an important role in transmitting distal olfactory nerve input from olfactory glomerulus to the soma-axon initial segment. To understand how dendritic active properties are involved in this transmission, we have combined dual soma and dendritic patch recordings with computational modeling to analyze action-potential initiation and propagation in the primary dendrite.
1 . Chen WR, Shen GY, Shepherd GM, Hines ML, Midtgaard J (2002) Multiple modes of action potential initiation and propagation in mitral cell primary dendrite. J Neurophysiol 88:2755-64 [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:
Cell Type(s): Olfactory bulb main mitral GLU cell; Myelinated neuron;
Channel(s): I Na,t; I K;
Gap Junctions:
Receptor(s): AMPA;
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Synaptic Integration; Olfaction;
Implementer(s): Hines, Michael [Michael.Hines at Yale.edu];
Search NeuronDB for information about:  Olfactory bulb main mitral GLU cell; AMPA; I Na,t; I K;
load_file(1, "fig3b.ses")

Fig 3B in the paper was constructed by:
Turning on the variable step method.
Selecting "KeepLines" in the grapher
Using Begin-End, Steps values for
Proximal 2-12, 20
Middle   2-6, 8   6-7.5, 50   7.5-12, 9
Distal   2-5, 6   5-5.8, 30   5.8-6, 20   6-6.5, 10   6.5-12, 11

for i=0, 1 {
        InhiSyn[i].gmaxampa = 0
        InhiSyn[i].gmaxnmda = 0

hoc_ac_ = .5
tuftden[1] PointProcessManager[1].move()
hoc_ac_ = .5
tuftden[0] PointProcessManager[2].move()
GluSyn[0].onset = 0
GluSyn[1].onset = 0
tstop = 12
steps_per_ms = 400

objref svec, pvec, tvec, mat, xvec, yvec
svec = new Vector()
pvec = new Vector()
tvec = new Vector()

mat = new Matrix(3,3)
func tmax() {local i, x, x1, x2, y, y1, y2
	// interpolated maximum under assumption of nonuniform t values
	i = $o1.max_ind
	if (i > 0 && i < $o1.size-1) {
		yvec = $o1.c(i-1,i+1)
		xvec = tvec.c(i-1,i+1)
		mat.setcol(0, xvec.c.mul(xvec))
		mat.setcol(1, xvec)
		mat.setcol(2, 1)
		yvec = mat.solv(yvec)
		if (yvec.x[0] <= 0) { // good, it's convex
			x = -yvec.x[1]/2/yvec.x[0]
			if (x >= xvec.x[0] && x <= xvec.x[2]) {
				// and we are in the original interval
				return x
		printf("failure in finding time of maximum around index %d\n", i)
		print "x"  xvec.printf
		print "y"  $o1.c(i-1,i+1).printf
		print "quadratic fit a*x^2 + b*x + c"  yvec.printf
	return tvec.x[i]

func spdiff() {
        GluSyn[0].gmaxampa = $1*1e-3
        GluSyn[1].gmaxampa = $1*1e-3
	GluSyn[0].gmaxnmda = $1*1e-3*.5
	GluSyn[1].gmaxnmda = $1*1e-3*.5
	return (tmax(svec) - tmax(pvec))

proc tuftlocate() {local i
	hoc_ac_ = $1
	tuftden[1] PointProcessManager[1].move()
	hoc_ac_ = $1
	tuftden[0] PointProcessManager[2].move()

xpanel("Synapse tuft location")
xradiobutton("proximal", "tuftlocate(.17)")
xradiobutton("middle", "tuftlocate(.5)", 1)
xradiobutton("distal", "tuftlocate(.83)")