Excitability of the soma in central nervous system neurons (Safronov et al 2000)

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Accession:62266
The ability of the soma of a spinal dorsal horn neuron, a spinal ventral horn neuron, and a hippocampal pyramidal neuron to generate action potentials was studied using experiments and computer simulations. By comparing recordings ... of a dorsal horn neuron with simulated responses, it was shown that computer models can be adequate for the study of somatic excitability. The modeled somata of both spinal neurons were unable to generate action potentials, showing only passive and local responses to current injections. ... In contrast to spinal neurons, the modeled soma of the hippocampal pyramidal neuron generated spikes with an overshoot of +9 mV. It is concluded that the somata of spinal neurons cannot generate action potentials and seem to resist their propagation from the axon to dendrites. ... See paper for more and details.
Reference:
1 . Safronov BV, Wolff M, Vogel W (2000) Excitability of the soma in central nervous system neurons. Biophys J 78:2998-3010 [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): Spinal cord lumbar motor neuron alpha ACh cell;
Channel(s): I Na,t; I A; I K;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Ion Channel Kinetics; Action Potentials;
Implementer(s): Safronov, Boris [safronov at ibmc.up.pt];
Search NeuronDB for information about:  Spinal cord lumbar motor neuron alpha ACh cell; I Na,t; I A; I K;
objectvar save_window_, rvp_
objectvar scene_vector_[5]
objectvar ocbox_, ocbox_list_, scene_, scene_list_
{ocbox_list_ = new List()  scene_list_ = new List()}

//Begin I/V Clamp Electrode
{
load_file("electrod.hoc")
}
{
ocbox_=new Electrode(0)
execute("can_locate=1 sec=\"soma\" xloc=0.5 locate(0)", ocbox_)
execute("vc.dur[0]=60 vc.amp[0]=-120", ocbox_)
execute("vc.dur[1]=50 vc.amp[1]=-10", ocbox_)
execute("vc.dur[2]=10 vc.amp[2]=-65", ocbox_)
execute("stim.del=10 stim.dur=5 stim.amp=0.02", ocbox_)
execute("vcsteps=5", ocbox_)
execute("samp=stim.amp  store_vclamp() glyph()", ocbox_)
ocbox_ = ocbox_.v1
ocbox_.map("I/V Clamp Electrode", 946, 448, 224.25, 371.25)
}
objref ocbox_
//End I/V Clamp Electrode


//Begin Insert/Remove Mechanisms
{
load_file("inserter.hoc", "Inserter")
}
{
soma ocbox_ = new Inserter(0)
}
{object_push(ocbox_)}
{
mt.select("pas") i = mt.selected()
ms[i] = new MechanismStandard("pas")
ms[i].set("g_pas", 4.5e-05, 0)
ms[i].set("e_pas", -70, 0)
mstate[i]= 1
maction(i)
mt.select("hh") i = mt.selected()
ms[i] = new MechanismStandard("hh")
ms[i].set("gnabar_hh", 0.12, 0)
ms[i].set("gkbar_hh", 0.036, 0)
ms[i].set("gl_hh", 0.0003, 0)
ms[i].set("el_hh", -54.3, 0)
mstate[i]= 0
mt.select("B_DR") i = mt.selected()
ms[i] = new MechanismStandard("B_DR")
ms[i].set("gkbar_B_DR", 0.00065, 0)
mstate[i]= 1
maction(i)
mt.select("B_A") i = mt.selected()
ms[i] = new MechanismStandard("B_A")
ms[i].set("gkbar_B_A", 0.00101, 0)
mstate[i]= 1
maction(i)
mt.select("B_Na") i = mt.selected()
ms[i] = new MechanismStandard("B_Na")
ms[i].set("gnabar_B_Na", 0.003214, 0)
mstate[i]= 1
maction(i)
}
{object_pop() doNotify()}
{
ocbox_ = ocbox_.v1
ocbox_.map("Insert/Remove Mechanisms", 14, 647, 114.75, 204.75)
}
objref ocbox_
//End Insert/Remove Mechanisms

{
xpanel("NEURON Main Panel", 0)
xcheckbox("Quiet",&stdrun_quiet,"")
realtime = 0
xvalue("Real Time","realtime", 0,"", 0, 1 )
celsius = 6.3
xvalue("celsius","celsius", 1,"", 0, 1 )
global_ra = 200
xvalue("Axial Resistivity","global_ra", 1,"set_ra()", 1, 1 )
xbutton("RunControl","nrncontrolmenu()")
xmenu("New Graph", 0)
xbutton("Voltage axis","newPlotV()")
xbutton("Current axis","newPlotI()")
xbutton("State axis","newPlotS()")
xbutton("Shape plot","newshapeplot()")
xbutton("Vector movie","newvectorplot()")
xbutton("Phase Plane","newphaseplane()")
xbutton("Grapher","load_proc(\"makegrapher\") makegrapher()")
xmenu()
xmenu("Point Processes", 0)
xmenu("Managers", 0)
xbutton("Point Manager","load_template(\"PointProcessManager\") makeppm()")
xbutton("Point Group","load_template(\"PointProcessGroupManager\") makeppgm()")
xbutton("Electrode","load_proc(\"makeelectrode\") makeelectrode()")
xmenu()
xmenu("Viewers", 0)
xmenu("PointProcesses", 0)
xbutton("IClamp","makePointBrowser(\"IClamp\")")
xbutton("AlphaSynapse","makePointBrowser(\"AlphaSynapse\")")
xbutton("SEClamp","makePointBrowser(\"SEClamp\")")
xbutton("VClamp","makePointBrowser(\"VClamp\")")
xbutton("APCount","makePointBrowser(\"APCount\")")
xmenu()
xmenu()
xmenu()
xmenu("Distributed Mechanisms", 0)
xmenu("Managers", 0)
xbutton("Inserter","load_template(\"Inserter\") makeinserter()")
xbutton("Homogeneous Spec","load_proc(\"makeshowmechanism\") makeshowmechanism()")
xmenu()
xmenu("Viewers", 0)
xbutton("Shape Name","load_template(\"MenuExplore\") makeMenuExplore()")
xbutton("Name Values","nrnallsectionmenu()")
xmenu("Mechanisms (Globals)", 0)
xbutton("na_ion","nrnglobalmechmenu(\"na_ion\")")
xbutton("k_ion","nrnglobalmechmenu(\"k_ion\")")
xbutton("hh","nrnglobalmechmenu(\"hh\")")
xmenu()
xmenu()
xmenu()
xmenu("Miscellaneous", 0)
xmenu("Clipboard", 0)
xbutton("Save to File","load_proc(\"clipboard_save\") clipboard_save()")
xbutton("Retrieve from File","load_proc(\"clipboard_retrieve\") clipboard_retrieve()")
xmenu()
xbutton("Family","load_template(\"Family\") makeFamily()")
xbutton("Parameterized Function","load_template(\"FunctionFitter\") makefitter()")
xbutton("Run Fitter","load_template(\"RunFitter\") makerunfitter()")
xmenu("Impedance", 0)
xbutton("Frequency","load_template(\"ImpedanceRatio\") makeImpRatio()")
xbutton("Path","load_template(\"Impx\") makeImpx()")
xbutton("log(A) vs x","load_template(\"LogAvsX\") makelogax()")
xbutton("Shape","load_template(\"ImpShape\") makeImpShape()")
xmenu()
xmenu()
xpanel(11,304)
}
{
xpanel("RunControl", 0)
v_init = -70
xvalue("Init","v_init", 1,"stdinit()", 1, 1 )
xbutton("Init & Run","run()")
xbutton("Stop","stoprun=1")
runStopAt = 5
xvalue("Continue til","runStopAt", 1,"{continuerun(runStopAt) stoprun=1}", 1, 1 )
runStopIn = 1
xvalue("Continue for","runStopIn", 1,"{continuerun(t + runStopIn) stoprun=1}", 1, 1 )
xbutton("Single Step","steprun()")
t = 120
xvalue("t","t", 2 )
tstop = 120
xvalue("Tstop","tstop", 1,"tstop_changed()", 0, 1 )
dt = 0.025
xvalue("dt","dt", 1,"setdt()", 0, 1 )
steps_per_ms = 20
xvalue("Points plotted/ms","steps_per_ms", 1,"setdt()", 0, 1 )
xpanel(637,511)
}
{
xpanel("soma(0 - 1) (Parameters)", 0)
xlabel("soma(0 - 1) (Parameters)")
xlabel("nseg = 1")
soma.L = 10
xvalue("L","soma.L", 1,"define_shape()", 0, 0 )
soma.diam = 10
xvalue("diam","soma.diam", 1,"", 0, 0 )
soma.cm = 1
xvalue("cm","soma.cm", 1,"", 0, 0 )
soma.gnabar_B_Na = 0.003214
xvalue("gnabar_B_Na","soma.gnabar_B_Na", 1,"", 0, 0 )
soma.ena = 53
xvalue("ena","soma.ena", 1,"", 0, 0 )
soma.gkbar_B_A = 0.00101
xvalue("gkbar_B_A","soma.gkbar_B_A", 1,"", 0, 0 )
soma.gkbar_B_DR = 0.00065
xvalue("gkbar_B_DR","soma.gkbar_B_DR", 1,"", 0, 0 )
soma.ek = -84
xvalue("ek","soma.ek", 1,"", 0, 0 )
soma.g_pas = 4.5e-05
xvalue("g_pas","soma.g_pas", 1,"", 0, 0 )
soma.e_pas = -70
xvalue("e_pas","soma.e_pas", 1,"", 0, 0 )
xpanel(296,511)
}
{
save_window_ = new Graph(0)
save_window_.size(50,80,-0.5,0.3)
scene_vector_[3] = save_window_
{save_window_.view(50, -0.5, 30, 0.8, 128, 8, 300.75, 158.5)}
graphList[1].append(save_window_)
save_window_.save_name("graphList[1].")
save_window_.xaxis(0,250,0,5,0,0,1)
save_window_.yaxis(-2,2,0,4,0,0,1)
save_window_.addvar("soma.ik_B_A( 0.5 )", 3, 1, 0.8, 0.9, 2)
save_window_.addexpr("soma.ik_B_DR( 0.5 )", 7, 1, 0.8, 0.9, 2)
save_window_.addexpr("soma.i_pas( 0.5 )", 4, 1, 0.8, 0.9, 2)
save_window_.addexpr("soma.ina_B_Na( 0.5 )", 2, 1, 0.8, 0.9, 2)
}
{
save_window_ = new Graph(0)
save_window_.size(0,120,-100,60)
scene_vector_[4] = save_window_
{save_window_.view(0, -100, 120, 160, 546, 5, 531, 268.75)}
graphList[0].append(save_window_)
save_window_.save_name("graphList[0].")
save_window_.addexpr("soma.v( 0.5 )", 1, 1, 0.8, 0.9, 2)
}
objectvar scene_vector_[1]
{doNotify()}

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