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

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Accession:19491
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.
Reference:
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]
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:
Receptor(s):
Gene(s):
Transmitter(s):
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 ualberta.ca];
Search NeuronDB for information about:  I L high threshold; I N; I Calcium;
// fig3A.hoc generates an approx to fig3A
// based on init.hoc whose header lines follow:
// This is the main file to call from the command line. By calling this file the
//associated files making up the component structure of the model will be loaded.
// AUTHOR: Kelvin Jones
// DATE: 980728

load_file("nrngui.hoc")		// for compatibility with Windows version
load_file("graphcopy.hoc")	// contains a proc to copy lines in graphs

xopen("morphology.hoc")		//retrieves the file with the morphological description
					//and names of the components of the model
// top left
print "top left"

// for fig3AB open all the membrane properties
// then set to zero the properties that are not desired for a particular figure

xopen("memb_N_soma.hoc")	//retrieves the file with the descriptions of the
xopen("memb_LLVA_soma.hoc")	//active and passive membrane properties of the model,
xopen("memb_LHVA_soma.hoc")	//their locations and densities

proc all_soma_ca_off() {
	soma {gcabar_N_Ca=0 gcabar_L_Ca=0 gcabar_L_HVA_Ca=0}
}

all_soma_ca_off()	//turn off all the soma Ca currents


access soma

xopen("voltage_step.ses")			// brings up the default windows

celsius = 36				// I put this here to make sure it doesn't
					// get changed by a ses file
// forall eca=60
execute("vcsteps=25",Electrode[0])
execute("vcincrement=2",Electrode[0])

// Graph[0].view(0, -300, 700, 320, 650, 320, 500, 360)
Graph[0].exec_menu("Keep Lines")
Graph[1].exec_menu("Keep Lines")
steps_per_ms = .1
dt = 10
execute("installFamily()",Electrode[0])	// switch to VClamp mode
init()

objref somaBox, g[6], vclamp_i_vec, soma_v_vec, t_vec, result_vec, outerBox

for i=0,5 {
	g[i] = new Graph(0)
}

proc addGraph() {
	$o2.intercept(1)
		graphlinecopy(Graph[0],g[$1])
	    	{g[$1].view(0, -300, 700, 320, 631, win_top, win_width, win_height)}
	$o2.intercept(0)
}

somaBox = new VBox()

all_soma_ca_off()
soma gcabar_N_Ca = 0.05	// Table 1
g[0].exec_menu("Keep Lines")
execute("varyamp(1)",Electrode[0])	// equiv to pressing "vary test level"
win_width = 350
win_height = 150
win_top = 20

	addGraph(0,somaBox)

all_soma_ca_off()
soma gcabar_L_Ca = 0.01	// Table 1
g[1].color(2)
Graph[0].exec_menu("Erase")
execute("varyamp(1)",Electrode[0])	// equiv to pressing "vary test level"

	addGraph(1,somaBox)

all_soma_ca_off()
soma gcabar_L_HVA_Ca = 0.01	// Table 1
g[2].color(3)
Graph[0].exec_menu("Erase")
execute("varyamp(1)",Electrode[0])	// equiv to pressing "vary test level"
	addGraph(2,somaBox)

somaBox.intercept(1)
        {Graph[1].view(0, -80, 700, 120, 631, win_top, win_width, win_height)}
somaBox.intercept(0)

somaBox.intercept(0)
somaBox.map("fig3aleft",20,100,-1,-1)


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