Medial vestibular neuron models (Quadroni and Knopfel 1994)

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Accession:53876
The structure and the parameters of the model cells were chosen to reproduce the responses of type A and type B MVNns as described in electrophysiological recordings. The emergence of oscillatory firing under these two specific experimental conditions is consistent with electrophysiological recordings not used during construction of the model. We, therefore, suggest that these models have a high predictive value.
Reference:
1 . Quadroni R, Knöpfel T (1994) Compartmental models of type A and type B guinea pig medial vestibular neurons. J Neurophysiol 72:1911-24 [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): Vestibular neuron;
Channel(s): I Na,p; I Na,t; I L high threshold; I T low threshold; I A; I K; I h;
Gap Junctions:
Receptor(s): NMDA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Oscillations; Action Potentials; Calcium dynamics;
Implementer(s): Morse, Tom [Tom.Morse at Yale.edu];
Search NeuronDB for information about:  NMDA; I Na,p; I Na,t; I L high threshold; I T low threshold; I A; I K; I h;
COMMENT
This file, ahp.mod, implements the after hyperpolarization (gAHP)  
current from Quadroni and Knopfel 1994 table 1
Note: this channel can be verified by testing if gives behavior specified in Quadroni
thesis, i.e. that channel is inactivated at cai concentration of 50 nM (5e-5 mM) and 
essentially activated at 500 nM (5e-4 mM) (at ten fold higher concentration )
ENDCOMMENT

NEURON {
	SUFFIX ahp
	USEION ca READ cai
	NONSPECIFIC_CURRENT i
	RANGE i, Erev, gbar, q, tau_q, qinf, betaq_const
}

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

PARAMETER {
	gbar = 2167e-6	(S/cm2) < 0, 1e9 >
	Erev = -82 (mV)
	cai (mM) : starts at 0.050 uM = 5e-8 (M) = 5e-5 mM
	betaq_const =  0.074	: Q+K 94
}

ASSIGNED {
	i (mA/cm2)
	v (mV)
	g (S/cm2)
	qinf
	tau_q (ms)
}

STATE {	q }

BREAKPOINT {
	SOLVE states METHOD cnexp
	g = gbar * q*q
	i = g * (v - Erev)
}

INITIAL {
	: assume that v has been constant for a long time
	q = alphaq(v)/(alphaq(v) + betaq(v))
}

DERIVATIVE states {
	rates(v)
	q' = (qinf - q)/tau_q
}

FUNCTION alphaq(Vm (mV)) (/ms) {
	UNITSOFF
	alphaq = 3.5e9 * (cai)^3
	UNITSON
}

FUNCTION betaq(Vm (mV)) (/ms) {
	UNITSOFF
	betaq = betaq_const
	UNITSON
}

FUNCTION tauq(Vm (mV)) (/ms) {
	UNITSOFF
	tauq = 1.0 / (alphaq(Vm) + betaq(Vm))
	UNITSON
}

PROCEDURE rates(Vm(mV)) {
	tau_q = tauq(Vm)
	qinf = alphaq(Vm) * tau_q      : change back to a/(a+b) if use tauq_min
}