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]
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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
images
README.html
cabal.mod *
nabalan.mod *
newcachan.mod *
newkca.mod *
newleak.mod
pump.mod *
slowhh3.mod
xtra.mod
anatscale.hoc *
calcrxc.hoc
cellrig.ses
field.hoc *
fixnseg.hoc *
iclampc.ses
initxrec.hoc
interpxyz.hoc *
morph_mouse.hoc
morph_rat.hoc
mosinit.hoc
msgic.hoc
parameters.hoc
rigc.ses
setpointers.hoc *
varstep.ses
vrecc.ses
                            
load_file("nrngui.hoc") 

//load_file("morph_rat.hoc")
load_file("morph_mouse.hoc")

load_file("fixnseg.hoc")

v_init = -62.6

clamp = 0                     /* switch for voltage clamp*/

tstart = 0
tstop = 500    /*time in msec*/

Dtmax = 1.0  
Dt = 1.00

dt = 5e-1 /*5e-4*/  

nainit=  4.075
vsolder=v_init
vsold=v_init

/*PARAMETERS*/
na_cond_s = 800.0e-6 		//200 for 3-domain model
na_cond_d = 800.0e-6 
kdr_cond_s = 840.0e-6  		//100 for 3-domain model
kdr_cond_d = 840.0e-6 
ca_cond = 0.3*11.196e-6
kca_cond = 0.2*59.0e-6  
a_cond_s = 570.e-6     
a_cond_d = 266e-6   


global_ra = 100     
forall Ra = global_ra
global_cm = 1.0
forall cm = global_cm
g_celsius = 37
celsius = g_celsius
forall ion_style("na_ion", 2,2,0,0,0)
access soma			/* All default references are to soma */

objectvar vc

proc init_cell() {
  forsec all { 
        {insert leak gnabar_leak = 2e-6 gkbar_leak = 3e-6}
  }
  forsec  somatic {
	{insert nabalan}
    	{insert hh3 gnabar_hh3 = na_cond_s gkhhbar_hh3 = kdr_cond_s gkabar_hh3 = a_cond_s}
    	{insert pump}
    	//{insert leak}
    	{insert cabalan}
    	{insert cachan gcalbar_cachan = ca_cond gkbar_cachan = 0.0}
    	{insert kca gkbar_kca = kca_cond}
  }

  forsec  basal {
  	{insert nabalan}
  	{insert hh3 gnabar_hh3 = na_cond_d  gkhhbar_hh3 = kdr_cond_d gkabar_hh3 = a_cond_d}
  	{insert pump}
    	//{insert leak}       
    	{insert cabalan}
    	{insert cachan gcalbar_cachan = ca_cond gkbar_cachan = 0.0 }
    	{insert kca gkbar_kca = kca_cond}
	}

  forsec excitozone {
  	{insert nabalan}
  	{insert hh3 gnabar_hh3 = 5*na_cond_d  gkhhbar_hh3 = 2*kdr_cond_d gkabar_hh3 = a_cond_d 
	shift_hh3 = 3 sshift_hh3 = 0}
	{insert pump}
    	//{insert leak}       
   	{insert cabalan}
   	{insert cachan gcalbar_cachan = ca_cond gkbar_cachan = 0.0 }
    	{insert kca gkbar_kca = kca_cond}
  }

  forsec axonal {
  	{insert nabalan}
  	{insert hh3 gnabar_hh3 = na_cond_d  gkhhbar_hh3 = kdr_cond_d gkabar_hh3 = a_cond_d}
	{insert pump}
    	//{insert leak}       
    	{insert cabalan}
    	{insert cachan gcalbar_cachan = ca_cond gkbar_cachan = 0.0 }
    	{insert kca gkbar_kca = kca_cond}
  }   

  forall cm = global_cm
  forall Ra = global_ra
  g_celsius = 35
}


tot=0
forall {tot=tot+nseg}
print "segments before ", tot
nseg=1


init_cell()


geom_nseg()
tot=0
forall {tot=tot+nseg}
print "actual segment count is ", tot

steps_per_ms = 40 
dt = 0.025 
tstop = 10