Dentate gyrus granule cell: subthreshold signal processing (Schmidt-Hieber et al. 2007)

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Detailed compartmental cable models of 8 hippocampal granule cells of adult mice were obtained from dual patch-clamp whole-cell recordings and subsequent 3D reconstructions. This code allows to reproduce figures 6-8 from the paper.
1 . Schmidt-Hieber C, Jonas P, Bischofberger J (2007) Subthreshold dendritic signal processing and coincidence detection in dentate gyrus granule cells. J Neurosci 27:8430-41 [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): Dentate gyrus granule GLU cell;
Gap Junctions:
Receptor(s): AMPA; Glutamate;
Transmitter(s): Glutamate;
Simulation Environment: NEURON;
Model Concept(s): Parameter Fitting; Influence of Dendritic Geometry; Synaptic Integration;
Implementer(s): Schmidt-Hieber, Christoph [ at];
Search NeuronDB for information about:  Dentate gyrus granule GLU cell; AMPA; Glutamate; Glutamate;
/* Sets nseg in each section to an odd value
   so that its segments are no longer than 
     d_lambda x the AC length constant
   at frequency freq in that section.

   Be sure to specify your own Ra and cm before calling geom_nseg()

   To understand why this works, 
   and the advantages of using an odd value for nseg,
   see  Hines, M.L. and Carnevale, N.T.
        NEURON: a tool for neuroscientists.
        The Neuroscientist 7:123-135, 2001.

// these are reasonable values for most models
freq = 1000 //original:100     // Hz, frequency at which AC length constant will be computed
d_lambda = 0.1 //original:0.1

func lambda_f() { local i, x1, x2, d1, d2, lam
        if (n3d() < 2) {
                return 1e5*sqrt(diam/(4*PI*$1*Ra*cm))
// above was too inaccurate with large variation in 3d diameter
// so now we use all 3-d points to get a better approximate lambda
        x1 = arc3d(0)
        d1 = diam3d(0)
        lam = 0
        for i=1, n3d()-1 {
                x2 = arc3d(i)
                d2 = diam3d(i)
                lam += (x2 - x1)/sqrt(d1 + d2)
                x1 = x2   d1 = d2
        //  length of the section in units of lambda
        lam *= sqrt(2) * 1e-5*sqrt(4*PI*$1*Ra*cm)

        return L/lam

proc geom_nseg_shared() {
  area(0.5) // make sure diam reflects 3d points
  forall { 
	if (debug_mode) printf("lambda=%g\n",lambda_f(freq))
	nseg = int((L/(d_lambda*lambda_f(freq))+0.9)/2)*2 + 1