Regulation of the firing pattern in dopamine neurons (Komendantov et al 2004)

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Accession:83547
Midbrain dopaminergic (DA) neurons in vivo exhibit two major firing patterns: single-spike firing and burst firing. The firing pattern expressed is dependent on both the intrinsic properties of the neurons and their excitatory and inhibitory synaptic inputs. Experimental data suggest that the activation of NMDA and GABAA receptors is crucial contributor to the initiation and suppression of burst firing, respectively, and that blocking calcium-activated potassium channels can facilitate burst firing. This multi-compartmental model of a DA neuron with a branching structure was developed and calibrated based on in vitro experimental data to explore the effects of different levels of activation of NMDA and GABAA receptors as well as the modulation of the SK current on the firing activity.
Reference:
1 . Komendantov AO, Komendantova OG, Johnson SW, Canavier CC (2004) A modeling study suggests complementary roles for GABAA and NMDA receptors and the SK channel in regulating the firing pattern in midbrain dopamine neurons. J Neurophysiol 91:346-57 [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; Electrogenic pump;
Brain Region(s)/Organism:
Cell Type(s): Substantia nigra pars compacta DA cell;
Channel(s): I A; I K; I K,Ca; I Sodium; I Calcium; Na/K pump;
Gap Junctions:
Receptor(s): GabaA; NMDA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Activity Patterns; Bursting; Detailed Neuronal Models; Sodium pump;
Implementer(s): Kuznetsova, Anna [anna.kuznetsova at utsa.edu];
Search NeuronDB for information about:  Substantia nigra pars compacta DA cell; GabaA; NMDA; I A; I K; I K,Ca; I Sodium; I Calcium; Na/K pump;
TITLE calcha.mod 
 
COMMENT
ENDCOMMENT
 
UNITS {
       (molar) = (1/liter)
        (S) = (siemens)
         (mA) = (milliamp)
        (mV) = (millivolt)
         F = (faraday) (coulomb)
        R = (mole k) (mV-coulomb/degC)
       (mM) =  (millimolar)

}
 
NEURON {
        SUFFIX calcha
        USEION ca READ cai WRITE ica
        RANGE gcalbar, gcanbar, gcahvabar, gcatbar,ica, ical,icat,ican,icahva,kml,kmn
        GLOBAL dlinf, dninf,  dtinf,ftinf,dhvainf,fhvainf
}
 
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
 
PARAMETER {
        v (mV)
        celsius = 35.0 (degC)
        dt (ms)
        gcatbar =  1044.0e-6 (S/cm2)
        gcanbar =  171.0e-6  (S/cm2)
        gcalbar =  216.0e-6  (S/cm2)
        gcahvabar =  0.0e-6  (S/cm2)
        kmn = 0.0001   (mM)
        kml = 0.00045  (mM)
        eca = 120 (mV)
        cao = 2.0 (mM)
        cai   (mM)

}
 
STATE {
        d_t dl dn dhva fhva ft
}
 
ASSIGNED {
        ica (mA/cm2)
        icahva (mA/cm2)
        ical (mA/cm2)
        ican (mA/cm2)
        icat (mA/cm2)
        dlinf dninf dtinf ftinf dhvainf fhvainf fninf flinf
}
 
BREAKPOINT {
        SOLVE states METHOD cnexp
        fninf = kmn/(kmn + cai)
        flinf = kml/(kml + cai)
        COMMENT
        eca = R*(celsius+273.15)/F*log(cao/cai)
        ENDCOMMENT
        icahva = gcahvabar*dhva*fhva*(v - eca)
        ical = gcalbar*dl*flinf*(v - eca)
        ican = gcanbar*dn*fninf*(v - eca)
        icat = gcatbar*d_t*ft*(v - eca)
        ica = icahva + ical + ican + icat
}
 
UNITSOFF
 
INITIAL {
        dhva = boltz(v,-10.0,10.0)
        dl = boltz(v,-50.0,3.0)
        dn = boltz(v,-45.0,7.0)
        d_t = boltz(v,-63.5,1.5)
        fhva = boltz(v,-48.0,-5.0)
        ft = boltz(v,-76.2,-3.0)
}

DERIVATIVE states {  :Computes state variables m, h, and n 
LOCAL dlinf,dninf,dtinf,ftinf,dhvainf,fhvain,dltau,dntau,dttau,fttau,dhvatau,fhvatau
        dhvainf = boltz(v,-10.0,10.0)
        dlinf = boltz(v,-50.0,3.0)
        dninf = boltz(v,-45.0,7.0)
        dtinf = boltz(v,-63.5,1.5)
        fhvainf = boltz(v,-48.0,-5.0)
        ftinf = boltz(v,-76.2,-3.0)
        dhvatau = gaussian(v,0.1,13.0,62.0,0.05)
        dltau = gaussian(v,18.0,20.0,45.0,1.50)
        dntau = gaussian(v,18.0,25.0,70.0,0.30)
        dttau = gaussian(v,65.0,6.32455,66.0,3.5)
        fhvatau = gaussian(v,0.5,18.0,55.6,0.50)
        fttau = gaussian(v,50.0,10.0,72.0,10.0)
        dhva' = (dhvainf-dhva)/dhvatau
        dl' = (dlinf-dl)/dltau
        dn' = (dninf-dn)/dntau
        d_t' = (dtinf-d_t)/dttau
        fhva' = (fhvainf-fhva)/fhvatau
        ft' = (ftinf-ft)/fttau
}
 
 
FUNCTION gaussian(v,a,b,c,d) {
        LOCAL arg
        arg= a*exp(-(c+v)*(v+c)/(b*b)) +d
        gaussian = arg
}
 
 
FUNCTION boltz(x,y,z) {
               LOCAL arg
                arg= -(x-y)/z
                if (arg > 50) {boltz = 0}
                else {if (arg < -50) {boltz = 1}
                else {boltz = 1.0/(1.0 + exp(arg))}}
}

 
UNITSON