Role of afferent-hair cell connectivity in determining spike train regularity (Holmes et al 2017)

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Accession:241240
"Vestibular bouton afferent terminals in turtle utricle can be categorized into four types depending on their location and terminal arbor structure: lateral extrastriolar (LES), striolar, juxtastriolar, and medial extrastriolar (MES). The terminal arbors of these afferents differ in surface area, total length, collecting area, number of boutons, number of bouton contacts per hair cell, and axon diameter (Huwe JA, Logan CJ, Williams B, Rowe MH, Peterson EH. J Neurophysiol 113: 2420 –2433, 2015). To understand how differences in terminal morphology and the resulting hair cell inputs might affect afferent response properties, we modeled representative afferents from each region, using reconstructed bouton afferents. ..."
Reference:
1 . Holmes WR, Huwe JA, Williams B, Rowe MH, Peterson EH (2017) Models of utricular bouton afferents: role of afferent-hair cell connectivity in determining spike train regularity. J Neurophysiol 117:1969-1986 [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; Axon;
Brain Region(s)/Organism: Turtle vestibular system;
Cell Type(s): Vestibular neuron; Turtle vestibular neuron;
Channel(s): I A; I h; I K; I K,Ca; I L high threshold; I M; I Na,t; I_KD;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potentials; Activity Patterns;
Implementer(s): Holmes, William [holmes at ohio.edu];
Search NeuronDB for information about:  I Na,t; I L high threshold; I A; I K; I M; I h; I K,Ca; I_KD;
TITLE SK channel
: SK channel following Hirschberg et al 1999 Biophys J 77:1905-1913 and Hirschberg et al 1998 J Gen Physiol 111:565-581


NEURON {
	SUFFIX 	SK
	USEION 	ca READ cai, cao, ica
	USEION	k READ ek WRITE ik
	RANGE 	gbar, g, i, inf_c, tau_c
:	GLOBAL	inf_c, tau_c
}

UNITS {
	(molar) = (1/liter)
	(mV) =	(millivolt)
	(mA) =	(milliamp)
	(mM) =	(millimolar)
	(pS)	=	(picosiemens)
	(um)	=	(micrometer)


	:FARADAY = 96520 (coul)
	:R = 8.3134 (joule/degC)
	FARADAY = (faraday) (coulomb)
	R = (k-mole) (joule/degC)
}

PARAMETER {
	gbar		= 	5 	(pS/um2)  :  Maximum conductance
	
	hill_c	=	4.64	: 2
	hill_t	=	2
	K_c		=	.00056	(mM)	: 0.56 uM
	tauA_c	=	45  	(ms)  : 50
	tau0_c	=	5	(ms)
:	shat_c	=	0.00035	(mM)
:	tauG_c	=	0.67			: left-right skew (0-1)
	diff		=	1	(1)	: diffusion factor
	cai0		=	50e-6	(mM)
	scale		=	1	(1)	: scaling for diffusion
}

ASSIGNED { 
:	celsius		(degC) : 32
	v		(mV)
	i		(mA/cm2)	
	ik		(mA/cm2)
	g		(pS/um2)
	ek		(mV)
	ica		(mA/cm2)
	cai		(mM)
	cao		(mM)
	inf_c
	tau_c		(ms)

}

STATE {
	c	: calcium dependent activation
}		

BREAKPOINT {
	SOLVE states METHOD cnexp
	g 	= 0
	g 	= gbar  * c
	i 	= g * (v - ek)*(1e-4)
	ik 	= i
}

INITIAL {
	cai=cai0
	rates( cai0)
	c = inf_c
}

DERIVATIVE states {
	rates(cai0+scale*(cai-cai0)) 
	c' = ( inf_c - c) / tau_c
}

PROCEDURE rates ( cai ( mM)) {
	inf_c = 1/(1 + (K_c/cai)^hill_c)
 	tau_c = tau0_c + tauA_c/(1 + (cai/K_c)^hill_t)
:	tau_c = tau0_c + 4*sqrt(tauG_c*(1-tauG_c))*tauA_c/(exp(tauG_c*(cai - K_c)/shat_c)+exp(-(1-tauG_c)*(cai-K_c)/shat_c))
}