Na+ channel dependence of AP initiation in cortical pyramidal neuron (Kole et al. 2008)

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Accession:114394
In this simulation action potential initiation, action potential properties and the role of axon initial segment Na+ channels are investigated in a realistic model of a layer 5 pyramidal neuron axon initial segment. The main Na+ channel properties were constrained by experimental data and the axon initial segment was reconstructed. Model parameters were constrained by direct recordings at the axon initial segment.
Reference:
1 . Kole MH, Ilschner SU, Kampa BM, Williams SR, Ruben PC, Stuart GJ (2008) Action potential generation requires a high sodium channel density in the axon initial segment. Nat Neurosci 11:178-86 [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): Neocortex V1 pyramidal corticothalamic L6 cell;
Channel(s): I Na,t; I K; I M; I h;
Gap Junctions:
Receptor(s):
Gene(s): HCN1; HCN2;
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Active Dendrites; Axonal Action Potentials; Action Potentials;
Implementer(s): Kole, Maarten [m.kole at nin.knaw.nl];
Search NeuronDB for information about:  Neocortex V1 pyramidal corticothalamic L6 cell; I Na,t; I K; I M; I h;
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NN_kole
readme.html
h.mod
Km.mod *
kv.mod *
Kv1.mod
na.mod *
nax.mod *
A3+AIS_original.hoc
figure6a.hoc
initiate_neuron.hoc
mosinit.hoc
panels.ses
screenshot.jpg
screenshot_adjust.jpg
screenshot_morphology.jpg
                            
COMMENT

Deterministic model of kinetics and voltage-dependence of Ih-currents
in layer 5 pyramidal neuron, see Kole et al., 2006. Implemented by
Stefan Hallermann.

Predominantly HCN1 / HCN2 

ENDCOMMENT

TITLE Ih-current

UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
     (mM) = (milli/liter)

}

INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}

PARAMETER {
	dt 	   		(ms)
	v 	   		(mV)
        ehd=-47 		(mV) 				       
	ghdbar=0.00015 (mho/cm2)	
	gamma_ih	:not used
	seed		:not used
}


NEURON {
	SUFFIX ih
	NONSPECIFIC_CURRENT Iqq
	RANGE Iqq,ghdbar
}

STATE {
	qq
}

ASSIGNED {
	Iqq (mA/cm2)
}

INITIAL {
	qq=alpha(v)/(beta(v)+alpha(v))
}

BREAKPOINT {
	SOLVE state METHOD cnexp
	Iqq = ghdbar*qq*(v-ehd)
}

FUNCTION alpha(v(mV)) {

	alpha = 0.001*6.43*(v+154.9)/(exp((v+154.9)/11.9)-1)
	: parameters are estimated by direct fitting of HH model to
        : activation time constants and voltage activation curve
        : recorded at 34C

}

FUNCTION beta(v(mV)) {
	beta = 0.001*193*exp(v/33.1)			
}

DERIVATIVE state {     : exact when v held constant; integrates over dt step
	qq' = (1-qq)*alpha(v) - qq*beta(v)
}

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