Fast sodium channel gating in mossy fiber axons (Schmidt-Hieber et al. 2010)

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"... To study the mechanisms underlying AP initiation in unmyelinated hippocampal mossy fibers of adult mice, we recorded sodium currents in axonal and somatic membrane patches. We demonstrate that sodium channel density in the proximal axon is ~5 times higher than in the soma. Furthermore, sodium channel activation and inactivation are ~2 times faster. Modeling revealed that the fast activation localized the initiation site to the proximal axon even upon strong synaptic stimulation, while fast inactivation contributed to energy-efficient membrane charging during APs. ..."
1 . Schmidt-Hieber C, Bischofberger J (2010) Fast sodium channel gating supports localized and efficient axonal action potential initiation. J Neurosci 30:10233-42 [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:
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation;
Search NeuronDB for information about:  Dentate gyrus granule GLU cell;
// ----------------------------------------------------------------------------
// config.hoc
// Configuration settings
// 2007-06-28, Christoph Schmidt-Hieber, University of Freiburg
// accompanies the publication:
// Schmidt-Hieber C, Jonas P, Bischofberger J (2007)
// Subthreshold Dendritic Signal Processing and Coincidence Detection 
// in Dentate Gyrus Granule Cells. J Neurosci 27:8430-8441
// send bug reports and suggestions to
// ----------------------------------------------------------------------------

verbose    =  1     // 0: no output
                    // 1: print essential information during simulations (default)

debug_mode =  0     // 0: no debug information (default)
                    // 1: show debug information

accuracy   =  0     // 0: compromise between accuracy and simulation speed (default)
                    // 1: Obsessively high level of accuracy 
                    //    Note that some simulations may take hours to run
                    //    with this setting.

celsius    = 24     // This is to roughly account for the effects of temperature on
q10_g_pas  =  1.98  // simulations. Passive membrane parameters (Ra, cm, g_pas) 
q10_Ra     =  0.80  // have no built-in temperature dependence. Instead, they
q10_cm     =  0.96  // will be scaled when calling membrane.hoc using Q10 values
                    // according to:
                    // Trevelyan AJ, Jack JJB (2002), J Physiol 539:623-636
                    // Note that these Q10 values have been obtained for LII/III
                    // pyramidal cells, not for granule cells.
                    // defaults:
                    // celsius    = 24    (our recording temperature)
                    // q10_g_pas  =  1.98 
                    // q10_Ra     =  0.80 
                    // q10_cm     =  0.96