Determinants of the intracellular and extracellular waveforms in DA neurons (Lopez-Jury et al 2018)

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Accession:244599
To systematically address the contribution of AIS, dendritic and somatic compartments to shaping the two-component action potentials (APs), we modeled APs of male mouse and rat dopaminergic neurons. A parsimonious two-domain model, with high (AIS) and lower (dendro-somatic) Na+ conductance, reproduced the notch in the temporal derivatives, but not in the extracellular APs, regardless of morphology. The notch was only revealed when somatic active currents were reduced, constraining the model to three domains. Thus, an initial AIS spike is followed by an actively generated spike by the axon-bearing dendrite (ABD), in turn followed mostly passively by the soma. Larger AISs and thinner ABD (but not soma-to-AIS distance) accentuate the AIS component.
Reference:
1 . López-Jury L, Meza RC, Brown MTC, Henny P, Canavier CC (2018) Morphological and Biophysical Determinants of the Intracellular and Extracellular Waveforms in Nigral Dopaminergic Neurons: A Computational Study. J Neurosci 38:8295-8310 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Extracellular; Dendrite; Neuron or other electrically excitable cell;
Brain Region(s)/Organism: Basal ganglia;
Cell Type(s): Substantia nigra pars compacta DA cell;
Channel(s): I Calcium; I K,Ca; Na/K pump; I L high threshold; I T low threshold; I A; I N; I Na,t; I K;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Pacemaking mechanism; Temporal Pattern Generation; Oscillations; Extracellular Fields;
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; I Calcium; Na/K pump;
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DAnotch_AIS
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README.html
cabal.mod *
nabalan.mod *
newcachan.mod *
newkca.mod *
newleak.mod
pump.mod *
slowhh3.mod
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fixnseg.hoc *
iclampc.ses
initxrec.hoc
interpxyz.hoc *
morph_mouse.hoc
morph_rat.hoc
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parameters.hoc
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varstep.ses
vrecc.ses
                            
TITLE Calcium ion accumulation without diffusion and buffering
 
                 
NEURON {
	SUFFIX cabalan
	USEION ca READ cai, ica WRITE cai
	RANGE  cainit, fCa , icapump,icapumpmax,km
}

UNITS {
	(molar) = (1/liter)
	(mM) =  (millimolar)
	(um) =  (micron)
	(mA) =  (milliamp)
	FARADAY = (faraday) (coulomb) 
	PI = (pi) (1)
}

PARAMETER {
         fCa = 0.05  (1)
         cainit = 0.00002 (mM)
        dt    (ms)
        celsius = 35  (degC)
        icapumpmax  = 0.00191  (mA/cm2)
        km = 0.000500         (mM)
         }

ASSIGNED {
	diam  (um)
	ica   (mA/cm2)
          icapump (mA/cm2)
}

STATE {
	cai (mM) <1e-10>
}

BREAKPOINT {
	SOLVE state METHOD sparse
}

INITIAL{
        cai=cainit
}

KINETIC state {
        icapump = icapumpmax*(1/(1 + km/cai))
	COMPARTMENT PI*diam*diam/4 {cai}
	 ~ cai << (-fCa*(ica +icapump)*PI*diam*(1e4)/(2*FARADAY))
}

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