The subcellular distribution of T-type Ca2+ channels in LGN interneurons (Allken et al. 2014)

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Accession:156039
" ...To study the relationship between the (Ca2+ channel) T-distribution and several (LGN interneuron) IN response properties, we here run a series of simulations where we vary the T-distribution in a multicompartmental IN model with a realistic morphology. We find that the somatic response to somatic current injection is facilitated by a high T-channel density in the soma-region. Conversely, a high T-channel density in the distal dendritic region is found to facilitate dendritic signalling in both the outward direction (increases the response in distal dendrites to somatic input) and the inward direction (the soma responds stronger to distal synaptic input). ..."
Reference:
1 . Allken V, Chepkoech JL, Einevoll GT, Halnes G (2014) The subcellular distribution of T-type Ca2+ channels in interneurons of the lateral geniculate nucleus. PLoS One 9:e107780 [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: Thalamus;
Cell Type(s): Thalamus lateral geniculate nucleus interneuron;
Channel(s): I L high threshold; I T low threshold; I h; I K,Ca; I CAN; I_AHP;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Dendritic Action Potentials; Active Dendrites; Conductance distributions;
Implementer(s): Allken, Vaneeda [vaneeda at gmail.com];
Search NeuronDB for information about:  I L high threshold; I T low threshold; I h; I K,Ca; I CAN; I_AHP; 
TITLE Medium duration Ca-dependent potassium current
:
:   Ca++ dependent K+ current IC responsible for medium duration AHP
:
:   Original file written by Alain Destexhe, Salk Institute, Nov 3, 1992
:   Modified by Geir Halnes, Norwegian University of Life Sciences, Mar 13, 2011


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

NEURON {
	SUFFIX iahp
	USEION k READ ek WRITE ik VALENCE 1
	USEION Ca READ Cai VALENCE 2
      RANGE gkbar, g, minf, taum
	GLOBAL beta, cac, m_inf, tau_m, x
}


UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
	(molar) = (1/liter)
	(mM) = (millimolar)
}


PARAMETER {
	v (mV)
	ek = -90 (mV)
	celsius = 36 (degC)
	Cai 	= 5e-5 (mM)			: Initial [Ca]i = 50 nM (Cai is simulated by separate mod-file)
	gkbar	= 1.3e-4	(mho/cm2)	: Conductance (modified from hoc-file)
	beta	= 0.02	(1/ms)	: Backward rate constant
	cac	= 4.3478e-4(mM)		: Middle point of m_inf fcn
	taumin	= 1	(ms)		: Minimal value of the time cst
      x       = 2				: Binding cites
}




STATE {
	m
}


ASSIGNED {
	ik 	(mA/cm2)
	g       (mho/cm2)
	m_inf
	tau_m	(ms)
	minf
      taum
	tadj
}


BREAKPOINT { 
	SOLVE states METHOD cnexp
        minf = m_inf
        taum = tau_m
	  g = gkbar*m*m
	  ik = g * (v - ek)
}

DERIVATIVE states { 
	evaluate_fct(v,Cai)
	m' = (m_inf - m) / tau_m
}


UNITSOFF
INITIAL {
:  activation kinetics are assumed to be at 22 deg. C
:  Q10 is assumed to be 3

	VERBATIM
	Cai = _ion_Cai;
	ENDVERBATIM

	tadj = 3 ^ ((celsius-22.0)/10)
	evaluate_fct(v,Cai)
	m = m_inf
      minf = m_inf
      taum = tau_m
}

PROCEDURE evaluate_fct(v(mV),Cai(mM)) {  LOCAL car, tcar
	car = (Cai/cac)^x
	m_inf = car / ( 1 + car )
	tau_m = 1 / beta / (1 + car) / tadj
      if(tau_m < taumin) { tau_m = taumin } 	: min value of time cst
}

UNITSON