Thalamic interneuron multicompartment model (Zhu et al. 1999)

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Accession:116862
This is an attempt to recreate a set of simulations originally performed in 1994 under NEURON version 3 and last tested in 1999. When I ran it now it did not behave exactly the same as previously which I suspect is due to some minor mod file changes on my side rather than due to any differences among versions. After playing around with the parameters a little bit I was able to get something that looks generally like a physiological trace in J Neurophysiol, 81:702--711, 1999, fig. 8b top trace. This sad preface is simply offered in order to encourage anyone who is interested in this model to make and post fixes. I'm happy to help out. Simulation by JJ Zhu To run nrnivmodl nrngui.hoc
References:
1 . Zhu JJ, Uhlrich DJ, Lytton WW (1999) Burst firing in identified rat geniculate interneurons. Neuroscience 91:1445-60 [PubMed]
2 . Zhu JJ, Lytton WW, Xue JT, Uhlrich DJ (1999) An intrinsic oscillation in interneurons of the rat lateral geniculate nucleus. J Neurophysiol 81:702-11 [PubMed]
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):
Channel(s): I Na,t; I L high threshold; I T low threshold; I K,leak; I h; I K,Ca; I CAN;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Bursting; Oscillations;
Implementer(s): Zhu, J. Julius [jjzhu at virginia.edu];
Search NeuronDB for information about:  I Na,t; I L high threshold; I T low threshold; I K,leak; I h; I K,Ca; I CAN;
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b09jan13
readme.html
AMPA.mod
cadecay.mod
clampex.mod *
cp.mod *
cp2.mod *
GABAA.mod
GABAB.mod
HH2.mod *
Iahp.mod *
Ican.mod *
Ih.mod *
IL.mod
IL3.mod *
IT.mod *
IT2.mod *
kdr2.mod *
kleak.mod *
kmbg.mod
naf2.mod *
nap.mod *
NMDA.mod
nthh.mod *
ntIh.mod *
ntleak.mod
ntt.mod *
pregencv.mod
vecst.mod
batch_.hoc
bg_cvode.inc
misc.h
mosinit.hoc *
netcon.inc
screenshot.jpg
                            
:$Id: IT.mod,v 1.12 2004/06/08 19:32:19 billl Exp $
TITLE Low threshold calcium current
:
:   Ca++ current responsible for low threshold spikes (LTS)
:   THALAMOCORTICAL CELLS
:   Differential equations
:
:   Model based on the data of Huguenard & McCormick, J Neurophysiol
:   68: 1373-1383, 1992 and Huguenard & Prince, J Neurosci.
:   12: 3804-3817, 1992.
:
:   Features:
:
:	- kinetics described by Nernst equations using a m2h format
:	- activation considered at steady-state
:	- inactivation fit to Huguenard's data using a bi-exp function
:	- shift for screening charge, q10 of inactivation of 3
:
:   Described in:
:    Destexhe, A., Bal, T., McCormick, D.A. and Sejnowski, T.J.  Ionic 
:    mechanisms underlying synchronized oscillations and propagating waves
:    in a model of ferret thalamic slices. Journal of Neurophysiology 76:
:    2049-2070, 1996.  (see http://www.cnl.salk.edu/~alain)
:
:
:   Alain Destexhe, Salk Institute and Laval University, 1995
:

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

NEURON {
	SUFFIX ittc
	USEION ca READ cai,cao WRITE ica
	GLOBAL q10m,q10h
	RANGE g, gmax, m_inf, tau_m, h_inf, tau_h, shift, i
}

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

	FARADAY = (faraday) (coulomb)
	R = (k-mole) (joule/degC)
}

PARAMETER {
	v		(mV)
	gmax	= 0.0022 (mho/cm2)
	q10m	= 3			: Q10 of activation
	q10h	= 3			: Q10 of inactivation
        exptemp = 24    (degC)
	shift	= 2 	(mV)		: corresponds to 2mM ext Ca++
	cai	= 2.4e-4 (mM)		: adjusted for eca=120 mV
	cao	= 2	(mM)
}

STATE {
  m h
}

ASSIGNED {
	g	(mho/cm2)
	i	(mA/cm2)
	ica	(mA/cm2)
	carev	(mV)
	m_inf
	tau_m	(ms)			: dummy variable for compatibility
	h_inf
	tau_h	(ms)
	phi_m
	phi_h
        celsius
}

BREAKPOINT {
	SOLVE states METHOD cnexp
	carev = (1e3) * (R*(celsius+273.15))/(2*FARADAY) * log (cao/cai)
	g = gmax * m * m * h
	i = g * (v-carev)
        ica = i
}

DERIVATIVE states {
	mh(v)

	m' = (m_inf - m) / tau_m
	h' = (h_inf - h) / tau_h
}


UNITSOFF
INITIAL {
:
:   Transformation to 36 deg assuming Q10 of 3 for h
:   (as in Coulter et al., J Physiol 414: 587, 1989)

	phi_m = q10m ^ ((celsius-exptemp)/10)
	phi_h = q10h ^ ((celsius-exptemp)/10)

	mh(v)
	h = h_inf
	m = m_inf
}

PROCEDURE mh (v(mV)) { LOCAL Vm

	Vm = v + shift

	m_inf = 1.0 / ( 1 + exp(-(Vm+57)/6.2) )
	h_inf = 1.0 / ( 1 + exp((Vm+81)/4.0) )

:       tau_m = (0.822/(exp(-(Vm+130  )/16.7) + exp((Vm+14.8)/18.2) ) + 0.480)/phi_m
        tau_m = (1  /  (exp(-(Vm+129.6)/16.7) + exp((Vm+14.8)/18.2) ) + 0.612)/phi_m
:	tau_h = ( 8.2+(56.6+0.27*exp((Vm+113.2)/5))/(1+exp((Vm+84)/3.2)))/phi_h
        tau_h = (30.8+(211.4  +  exp((Vm+113.2)/5))/(1+exp((Vm+84)/3.2)))/phi_h
}

UNITSON

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