CA1 pyramidal neuron: functional significance of axonal Kv7 channels (Shah et al. 2008)

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Accession:112546
The model used in this paper confirmed the experimental findings suggesting that axonal Kv7 channels are critically and uniquely required for determining the inherent spontaneous firing of hippocampal CA1 pyramids, independently of alterations in synaptic activity. The model predicts that the axonal Kv7 density could be 3-5 times that at the soma.
Reference:
1 . Shah MM, Migliore M, Valencia I, Cooper EC, Brown DA (2008) Functional significance of axonal Kv7 channels in hippocampal pyramidal neurons. Proc Natl Acad Sci U S A 105(22):7869-7874 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell; Axon; Channel/Receptor;
Brain Region(s)/Organism:
Cell Type(s): Hippocampus CA1 pyramidal cell;
Channel(s): I Na,t; I T low threshold; I A; I K; I M; I Calcium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Detailed Neuronal Models; Axonal Action Potentials; Action Potentials;
Implementer(s): Migliore, Michele [Michele.Migliore at Yale.edu];
Search NeuronDB for information about:  Hippocampus CA1 pyramidal cell; I Na,t; I T low threshold; I A; I K; I M; I Calcium;
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readme.html
cacumm.mod *
cagk.mod
cal2.mod
can2.mod
cat.mod *
h.mod *
kadist.mod *
KahpM95.mod *
kaprox.mod *
kdrca1.mod *
km.mod *
na3n.mod *
naxn.mod *
fig4a.hoc
fixnseg.hoc *
geo9068802.hoc *
mosinit.hoc *
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COMMENT
	calcium accumulation into a volume of area*depth next to the
	membrane with a decay (time constant tau) to resting level
	given by the global calcium variable cai0_ca_ion
	Modified to include a resting current (irest) and peak value
	(cmax)
	i is a dummy current needed to force a BREAKPOINT
ENDCOMMENT

NEURON {
	SUFFIX cacum
	USEION ca READ ica WRITE cai
	NONSPECIFIC_CURRENT i
	RANGE depth, tau, cai0, cmax
}

UNITS {
	(mM) = (milli/liter)
	(mA) = (milliamp)
	F = (faraday) (coulombs)
}

PARAMETER {
	depth = 0.1 (um)	: assume volume = area*depth
	irest = 0  (mA/cm2)		: to be initialized in hoc	
	tau = 100 (ms)
	cai0 = 50e-6 (mM)	: Requires explicit use in INITIAL
			: block for it to take precedence over cai0_ca_ion
			: Do not forget to initialize in hoc if different
			: from this default.
}

ASSIGNED {
	ica (mA/cm2)
	cmax
	i  	 (mA/cm2)
}

STATE {
	cai (mM)
}

INITIAL {
	cai = cai0
	irest = ica
	cmax=cai
}

BREAKPOINT {
	SOLVE integrate METHOD derivimplicit
	if (cai>cmax) {cmax=cai}
	i=0
}

DERIVATIVE integrate {
	cai' = (irest-ica)/depth/F/2 * (1e4) + (cai0 - cai)/tau
}

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