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(30):10233-10242 [PubMed]
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 cell;
Gap Junctions:
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation;
Search NeuronDB for information about:  Dentate gyrus granule cell;
This code accompanies the publication:

Schmidt-Hieber C, Bischofberger J. (2010)
Fast sodium channel gating supports localized and efficient 
axonal action potential initiation.
J Neurosci 30:10233-42

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1. Install the required Python modules:
NumPy (
SciPy (
Matplotlib (

Installation instructions can be found on the respective web sites.

2. NEURON and Python
Install NEURON with Python support. At the time of writing,
the binary distribution won't do and you'll have to compile
NEURON from source.

for instructions.

3. Optional
To solve kinetic gating schemes without NEURON, you'll need pyqmatrix:


1. Compile the mechanism files in the mod directory:
$ nrnivmodl mod

2. Run the example simulations:

# Simple current-clamp simulation
$ python

# Voltage-clamp simulation comparing Q-Matrix and NEURON results:
$ python


na8st-1.1 (1.1)

  * Pointing out discrepancies in \bar{g}_{Na} computations.
    Thanks to Steffen Platschek for pointing this out.

 -- Christoph Schmidt-Hieber <>  Sun, 20 Oct 2011 13:41:23 +0000

20150903 a patch (contributed by Arnd Roth and emailed by Christoph
Schmidt-Hieber) that adds temperature dependence was applied to

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