Dendritic L-type Ca currents in motoneurons (Carlin et al 2000)

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A component of recorded currents demonstrated kinetics consistent with a current originating at a site spatially segregated from the soma. In response to step commands this component was seen as a late-onset, low amplitude persistent current whilst in response to depolarizing-repolarizing ramp commands a low voltage clockwise current hysteresis was recorded. Simulations using a neuromorphic motoneuron model could reproduce these currents only if a noninactivating calcium conductance was placed in the dendritic compartments.
1 . Carlin KP, Jones KE, Jiang Z, Jordan LM, Brownstone RM (2000) Dendritic L-type calcium currents in mouse spinal motoneurons: implications for bistability. Eur J Neurosci 12:1635-46 [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):
Channel(s): I L high threshold; I N; I Calcium;
Gap Junctions:
Simulation Environment: NEURON;
Model Concept(s): Bursting; Ion Channel Kinetics; Active Dendrites; Influence of Dendritic Geometry; Detailed Neuronal Models; Dendritic Bistability;
Implementer(s): Jones, Kelvin E [KEJones at];
Search NeuronDB for information about:  I L high threshold; I N; I Calcium;
// This file is used to assign active and passive properties to the compartments of the model.
// Values for maximum Calcium channel conductance (S/cm^2) are given in Table 1, Eur J Neurosci (2000) 12:1635-1646
// AUTHOR: Kelvin Jones
// DATE: May 6, 1999

		//								//
		//	N_Ca on dendrites			//
		//	Fig 3A						//
		//								//

	set_ra(70)	// (ohm-cm) I set this because I got worried when I
			// saw a default of 35.4 in the NEURON Main Panel
			// although all compartments had the right value
forall	{
	insert pas
	g_pas=1/11000		// memb resistance in dendrites is 11 kOhm-cm^2
	insert N_Ca
	gcabar_N_Ca = 0.002	// Table 1
soma	{
	g_pas = 1/250		// memb resistance in soma is 0.25 kOhm-cm^2
	gcabar_N_Ca = 0		// no N-type current in soma

hillock	{
	gcabar_N_Ca = 0
is	{
	gcabar_N_Ca = 0

// The dendritically located current is on third order dendrites and greater
// so the conductance elsewhere is set to zero.
forsec "o0" gcabar_N_Ca = 0
forsec "o1" gcabar_N_Ca = 0
forsec "o2" gcabar_N_Ca = 0