CN bushy, stellate neurons (Rothman, Manis 2003)

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Accession:37857
Using kinetic data from three different K+ currents in acutely isolated neurons, a single electrical compartment model representing the soma of a ventral cochlear nucleus (VCN) neuron was created. The K+ currents include a fast transient current (IA), a slow-inactivating low-threshold current (ILT), and a noninactivating high-threshold current (IHT). The model also includes a fast-inactivating Na+ current, a hyperpolarization-activated cation current (Ih), and 1-50 auditory nerve synapses. With this model, the role IA, ILT, and IHT play in shaping the discharge patterns of VCN cells is explored. Simulation results indicate these currents have specific roles in shaping the firing patterns of stellate and bushy CN cells. (see readme.txt and the papers, esp 2003c, for details). Any questions regarding these implementations should be directed to: pmanis@med.unc.edu 2 April 2004 Paul B Manis, Ph.D.
References:
1 . Rothman JS, Manis PB (2003) The roles potassium currents play in regulating the electrical activity of ventral cochlear nucleus neurons. J Neurophysiol 89:3097-113 [PubMed]
2 . Rothman JS, Manis PB (2003) Kinetic analyses of three distinct potassium conductances in ventral cochlear nucleus neurons. J Neurophysiol 89:3083-96 [PubMed]
3 . Rothman JS, Manis PB (2003) Differential expression of three distinct potassium currents in the ventral cochlear nucleus. J Neurophysiol 89:3070-82 [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:
Cell Type(s): Cochlear nucleus bushy GLU cell; CN stellate cell;
Channel(s): I Na,p; I Na,t; I L high threshold; I A; I K; I K,leak; I Sodium; I Potassium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Temporal Pattern Generation; Action Potentials; Audition;
Implementer(s): Manis, Paul B [PManis at med.unc.edu];
Search NeuronDB for information about:  Cochlear nucleus bushy GLU cell; I Na,p; I Na,t; I L high threshold; I A; I K; I K,leak; I Sodium; I Potassium;
TITLE jsr.mod  VCN conductances

COMMENT
Ih for VCN neurons - average from several studies in auditory neurons


Implementation by Paul B. Manis, April (JHU) and Sept, (UNC)1999.
revised 2/28/04 pbm

pmanis@med.unc.edu

ENDCOMMENT

UNITS {
        (mA) = (milliamp)
        (mV) = (millivolt)
        (nA) = (nanoamp)
}

NEURON {
        SUFFIX ih
        NONSPECIFIC_CURRENT i
        RANGE ghbar, gh, ih
        GLOBAL rinf, rtau
}

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

PARAMETER {
        v (mV)
        celsius = 22 (degC)
        dt (ms)
        ghbar = 0.00318 (mho/cm2) <0,1e9>
        eh = -43 (mV)
}

STATE {
        r
}

ASSIGNED {
	gh (mho/cm2)
	i (mA/cm2)
	rinf
    rtau (ms)
}

LOCAL rexp

BREAKPOINT {
	SOLVE states
    
	gh = ghbar*r
    i = gh*(v - eh)
    }

UNITSOFF

INITIAL {
    trates(v)
    r = rinf
}

PROCEDURE states() {  :Computes state variables m, h, and n
	trates(v)      :             at the current v and dt.
	r = r + rexp*(rinf-r)
VERBATIM
	return 0;
ENDVERBATIM
}

LOCAL q10
PROCEDURE rates(v) {  :Computes rate and other constants at current v.
                      :Call once from HOC to initialize inf at resting v.

	q10 = 3^((celsius - 22)/10)
    rinf = 1 / (1+exp((v + 76) / 7))
    rtau = (100000 / (237*exp((v+60) / 12) + 17*exp(-(v+60) / 14))) + 25

}

PROCEDURE trates(v) {  :Computes rate and other constants at current v.
                      :Call once from HOC to initialize inf at resting v.
	LOCAL tinc
	TABLE rinf, rexp
	DEPEND dt, celsius FROM -200 TO 150 WITH 350

    rates(v)    : not consistently executed from here if usetable_hh == 1
        : so don't expect the tau values to be tracking along with
        : the inf values in hoc

	tinc = -dt * q10
	rexp = 1 - exp(tinc/rtau)
}

FUNCTION vtrap(x,y) {  :Traps for 0 in denominator of rate eqns.
        if (fabs(x/y) < 1e-6) {
                vtrap = y*(1 - x/y/2)
        }else{
                vtrap = x/(exp(x/y) - 1)
        }
}

UNITSON

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