Role of the AIS in the control of spontaneous frequency of dopaminergic neurons (Meza et al 2017)

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Accession:235320
Computational modeling showed that the size of the Axon Initial Segment (AIS), but not its position within the somatodendritic domain, is the major causal determinant of the tonic firing rate in the intact model, by virtue of the higher intrinsic frequency of the isolated AIS. Further mechanistic analysis of the relationship between neuronal morphology and firing rate showed that dopaminergic neurons function as a coupled oscillator whose frequency of discharge results from a compromise between AIS and somatodendritic oscillators.
Reference:
1 . Meza RC, López-Jury L, Canavier CC, Henny P (2018) Role of the Axon Initial Segment in the Control of Spontaneous Frequency of Nigral Dopaminergic Neurons In Vivo. J Neurosci 38:733-744 [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: Basal ganglia; Mouse;
Cell Type(s): Substantia nigra pars compacta DA cell;
Channel(s): Na/K pump; I K,Ca; I K; I L high threshold; I T low threshold; I A; I N; I Na,t;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Activity Patterns; Temporal Pattern Generation; Oscillations; Pacemaking mechanism;
Implementer(s): Lopez-Jury, Luciana [lucianalopezjury at gmail.com]; Canavier, CC;
Search NeuronDB for information about:  Substantia nigra pars compacta DA cell; I Na,t; I L high threshold; I N; I T low threshold; I A; I K; I K,Ca; Na/K pump;
TITLE Leak current including GABA_A receptor current
 

UNITS {
        (pA) = (picoamp)
        (molar) = (1/liter)
	(mV) =	(millivolt)
        (S)  =  (siemens)
	(mA) =	(milliamp)
	(mM) =	(millimolar)
         F = (faraday) (coulomb)
         R = (mole k)  (mV-coulomb/degC)
}


INDEPENDENT {v FROM -100 TO 50 WITH 50 (mV)}

NEURON {
	SUFFIX leak
	USEION ca WRITE ica
	USEION na READ nai,ena  WRITE ina
	USEION k  WRITE ik
	USEION cl WRITE icl VALENCE 1
	RANGE  gcabar,ileak,ina,ica,ik,gnabar,gkbar,nai,ggabaa
 
}

PARAMETER {
        dt      (ms)
        ena     (mV)
        nai     (mM)
        celsius = 35      (degC)
        gkbar   = 5.5e-6 (S/cm2)
        gnabar  = 2.375e-6  (S/cm2)
        gcabar  = 0.0136e-6  (S/cm2)
        ggabaa  = 0.0e-6  (S/cm2)
        eca =   120 (mV)
        ecl =  -70  (mV)
        ek  =  -90.0 (mV)
        nao =   145 (mM)
        
}

ASSIGNED { 
           ica	  (mA/cm2)
           ina	  (mA/cm2)
           ik	  (mA/cm2)
           icl	  (mA/cm2)
           ileak  (mA/cm2)
}


BREAKPOINT {
	nai = 0.81
        ena = R*(celsius+273.15)/F*log(nao/nai)
	:ena = 77.0
	ica = gcabar*(v-eca)
	ina = gnabar*(v-ena)
	icl = ggabaa*(v-ecl)
	ik = gkbar*(v-ek)
        ileak= ica + ina + ik + icl 
}

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