AP back-prop. explains threshold variability and rapid rise (McCormick et al. 2007, Yu et al. 2008)

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Accession:135839
This simple axon-soma model explained how the rapid rising phase in the somatic spike is derived from the propagated axon initiated spike, and how the somatic spike threshold variance is affected by spike propagation.
References:
1 . McCormick DA, Shu Y, Yu Y (2007) Neurophysiology: Hodgkin and Huxley model--still standing? Nature 445:E1-2; discussion E2-3 [PubMed]
2 . Yu Y, Shu Y, McCormick DA (2008) Cortical action potential backpropagation explains spike threshold variability and rapid-onset kinetics. J Neurosci 28:7260-72 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell; Axon;
Brain Region(s)/Organism: Neocortex;
Cell Type(s): Neocortex V1 L6 pyramidal corticothalamic cell; Neocortex V1 L2/6 pyramidal intratelencephalic cell;
Channel(s): I Na,t; I L high threshold; I T low threshold; I A; I K; I M; I h; I K,Ca; I_AHP;
Gap Junctions:
Receptor(s): GabaA; NMDA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Detailed Neuronal Models;
Implementer(s):
Search NeuronDB for information about:  Neocortex V1 L6 pyramidal corticothalamic cell; Neocortex V1 L2/6 pyramidal intratelencephalic cell; GabaA; NMDA; I Na,t; I L high threshold; I T low threshold; I A; I K; I M; I h; I K,Ca; I_AHP;
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McCormickEtAl2007YuEtAl2008
readme.txt
ca.mod *
cad.mod *
caL3d.mod *
capump.mod
gabaa5.mod *
Gfluct.mod *
ia.mod *
iahp.mod *
iahp2.mod *
ih.mod
im.mod *
kca.mod *
km.mod *
kv.mod *
na.mod *
NMDA_Mg.mod *
nmda5.mod *
release.mod *
for_plot_spike.m
mosinit.hoc
neuron_soma.dat
Rapid_rising_somatic_spike_soma_axon.hoc
                            
TITLE transient potassium current (A-current)

COMMENT
	*********************************************
	reference:	Huguenard & McCormick (1992) 
			J.Neurophysiology 68(4), 1373-1383
	found in:	thalamic relay neurons		 	
	*********************************************
	Original by Alain Destexhe
	Rewritten for MyFirstNEURON by Arthur Houweling
ENDCOMMENT

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

NEURON {
	SUFFIX iA
	USEION k READ ek WRITE ik 
        RANGE gkbar, m_inf1, tau_m, h_inf, tau_h1, ik
}

UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
}

PARAMETER {
	v		(mV)
	celsius		(degC)
	dt		(ms)
	ek		(mV)
	gkbar= 0.009	(mho/cm2)
:	gkbar= 0.00345	(mho/cm2)
}

STATE {
	m1 h1
}

ASSIGNED {
	ik		(mA/cm2)
	m_inf1
	tau_m		(ms)
	h_inf
	tau_h1		(ms)
	tadj
}

BREAKPOINT { 
	SOLVE states :METHOD euler
 	ik = gkbar * m1^4*h1 * (v-ek)
}

:DERIVATIVE states { 
:	evaluate_fct(v)
:
:	m1'= (m_inf1-m1) / tau_m
:	h1'= (h_inf-h1) / tau_h1
:}

PROCEDURE states() {
        evaluate_fct(v)

	m1= m1 + (1-exp(-dt/tau_m))*(m_inf1-m1)
	h1= h1 + (1-exp(-dt/tau_h1))*(h_inf-h1)
}

UNITSOFF
INITIAL {
:	tadj = 2.3^((celsius-23)/10)
	tadj = 3^((celsius-23.5)/10)
	evaluate_fct(v)
	m1 = m_inf1
        h1 = h_inf
}

PROCEDURE evaluate_fct(v(mV)) {  LOCAL a,b
	tau_m = 1.0/((exp((v+35.82)/19.69)+exp(-(v+79.69)/12.7))+0.37) / tadj
	m_inf1 = 1.0 / (1+exp(-(v+60)/8.5))
	a = 1.0/((exp((v+46.05)/5)+exp(-(v+238.4)/37.45))) / tadj
	if (v<-63) {
		tau_h1 = a
		}
	else {
		tau_h1 = 19.0/tadj
		}
	h_inf = 1.0/(1+exp((v+78)/6))
}
UNITSON

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