Current flow during PAP in squid axon at diameter change (Joyner et al 1980)

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Accession:9853
From the paper abstract: An impulse ... sees an increased electrical load at regions of increasing diameter or at branch points with certain morphologies. We present here theoretical and experimental studies on the changes in membrane current and axial current associated with diameter changes. The theoretical studies were done with numerical solutions for cable equations that were generalized to include a varying diameter; the Hodgkin-Huxley equations were used to represent the membrane properties. ... As an action potential approaches a region of increased electrical load, the action potential amplitude and rate of rise decrease, but there is a marked increase in the magnitude of the inward sodium current. ... (See paper for more details.)
Reference:
1 . Joyner RW, Westerfield M, Moore JW (1980) Effects of cellular geometry on current flow during a propagated action potential. Biophys J 31:183-94 [PubMed]
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Model Information (Click on a link to find other models with that property)
Model Type: Axon;
Brain Region(s)/Organism:
Cell Type(s):
Channel(s): I Na,t; I K;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Influence of Dendritic Geometry; Axonal Action Potentials;
Implementer(s): Hines, Michael [Michael.Hines at Yale.edu];
Search NeuronDB for information about:  I Na,t; I K;
objectvar save_window_, rvp_
objectvar scene_vector_[8]
objectvar ocbox_, ocbox_list_, scene_, scene_list_
{ocbox_list_ = new List()  scene_list_ = new List()}
{pwman_place(0,0,0)}

//Begin CellBuild[0]
{
load_file("celbild.hoc", "CellBuild")
}
{ocbox_ = new CellBuild(1)}
{object_push(ocbox_)}
{
version(5.1)
continuous = 1
}
{object_push(topol)}
{
first = 0
slist.remove_all()
sname = "axon"
objref tobj
}
{
tobj = new CellBuildSection("soma",0, 0, tobj, 0) slist.append(tobj)
  tobj.position(0,0,45,15) tobj.lx=37.5 tobj.ly=15 tobj.i3d=0
tobj = new CellBuildSection("axon",0, 0, tobj, 0) slist.append(tobj)
tobj.parent=slist.object(0)
  tobj.position(0,0,-90,0) tobj.lx=-45 tobj.ly=0 tobj.i3d=0
all_init()
}
for i=0, slist.count-1 {slist.object(i).rdses()}
{object_pop()}
{
}
{object_push(subsets)}
{first = 0}
{consist()}
{object_pop()}
{
}
{object_push(geom)}
{
first = 0
tobj = new GeoSpec(6)
tobj.value = 500
bild.subsets.snlist.object(0).geo.append(tobj)
tobj = new GeoSpec(0)
tobj.value = 15000
bild.topol.slist.object(0).geo.append(tobj)
tobj = new GeoSpec(1)
tobj.value = 550
bild.topol.slist.object(0).geo.append(tobj)
tobj = new GeoSpec(0)
tobj.value = 15000
bild.topol.slist.object(1).geo.append(tobj)
tobj = new GeoSpec(1)
tobj.value = 100
bild.topol.slist.object(1).geo.append(tobj)
set_default()
}
{object_pop()}
{
}
{object_push(memb)}
{first=0}
{
tobj = new MechanismStandard("hh")
tobj.set("gnabar_hh", 0.12, 0)
tobj.set("gkbar_hh", 0.036, 0)
tobj.set("gl_hh", 0.0003, 0)
tobj.set("el_hh", -54.3, 0)
tobj = new MStanWrap(tobj, 1)
bild.subsets.snlist.object(0).ml.append(tobj)
}
{
tobj = new GeoSpec(0)
tobj.value = 35.4
tobj.set_default()
tobj = new MStanWrap(tobj, 0)
bild.subsets.snlist.object(0).ml.append(tobj)
}
{
tobj = new GeoSpec(1)
tobj.value = 1
tobj.set_default()
tobj = new MStanWrap(tobj, 0)
bild.subsets.snlist.object(0).ml.append(tobj)
}
{
tobj = new GeoSpec(0)
tobj.value = 80
tobj.set_default()
tobj = new MStanWrap(tobj, 0)
bild.topol.slist.object(0).ml.append(tobj)
}
{
tobj = new GeoSpec(0)
tobj.value = 80
tobj.set_default()
tobj = new MStanWrap(tobj, 0)
bild.topol.slist.object(1).ml.append(tobj)
}
{object_pop()}
{
}
{object_push(manage)}
{
first = 0
classname = "Cell"
etop=1 esub=1 egeom=1 emem=1
itop=1 isub=0 igeom=0 imem=0
bild.topol.names_off = 0
bild.topol.circles_off = 0
}
{object_pop()}
{
cexport()
}
{object_pop()}
{
save_window_=ocbox_.gtopol
save_window_.size(-200,200,-150,150)
scene_vector_[2] = save_window_
ocbox_.gtopol = save_window_
save_window_.save_name("ocbox_.gtopol")
}
{
ocbox_.map("CellBuild[0]", 396, 26, 599.4, 522)
}
objref ocbox_
//End CellBuild[0]

{WindowMenu[0].ses_gid(1, 0, 0, "cell")}

//Begin PointProcessManager
{
load_file("pointman.hoc")
}
{
axon ocbox_ = new PointProcessManager(0)
}
{object_push(ocbox_)}
{
mt.select("IClamp") i = mt.selected()
ms[i] = new MechanismStandard("IClamp")
ms[i].set("del", 0, 0)
ms[i].set("dur", 0.1, 0)
ms[i].set("amp", 2000, 0)
mt.select("IClamp") i = mt.selected() maction(i)
hoc_ac_ = 1
sec.sec move() d1.flip_to(0)
}
{object_pop() doNotify()}
{
ocbox_ = ocbox_.v1
ocbox_.map("PointProcessManager", 148, 526, 216.9, 262.8)
}
objref ocbox_
//End PointProcessManager

{
xpanel("RunControl", 0)
v_init = -65
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 = 6
xvalue("t","t", 2 )
tstop = 6
xvalue("Tstop","tstop", 1,"tstop_changed()", 0, 1 )
dt = 0.005
xvalue("dt","dt", 1,"setdt()", 0, 1 )
steps_per_ms = 100
xvalue("Points plotted/ms","steps_per_ms", 1,"setdt()", 0, 1 )
xcheckbox("Quiet",&stdrun_quiet,"")
realtime = 1
xvalue("Real Time","realtime", 0,"", 0, 1 )
xpanel(148,99)
}
{
xpanel("Temperature", 0)
celsius = 16
xvalue("celsius","celsius", 1,"", 0, 1 )
xpanel(372,6)
}
{
xpanel("Figures for Joyner et. al, 1980", 0)
xradiobutton("Fig 2","restart(\"fig2\")")
xradiobutton("Fig 3","restart(\"fig3\")")
xradiobutton("Fig 4","restart(\"fig4\")")
xradiobutton("Fig 5","restart(\"fig5\")")
xradiobutton("Fig 7","restart(\"fig7\")")
xpanel(2,98)
}
{
xpanel("Figures for Joyner et. al, 1980", 0)
xradiobutton("Fig 2","restart(\"fig2\")")
xradiobutton("Fig 3","restart(\"fig3\")")
xradiobutton("Fig 4","restart(\"fig4\")")
xradiobutton("Fig 5","restart(\"fig5\")")
xradiobutton("Fig 7","restart(\"fig7\")")
xpanel(3,98)
}
{
xpanel("Figures for Joyner et. al, 1980", 0)
xradiobutton("Fig 2","restart(\"fig2\")")
xradiobutton("Fig 3","restart(\"fig3\")")
xradiobutton("Fig 4","restart(\"fig4\")")
xradiobutton("Fig 5","restart(\"fig5\")")
xradiobutton("Fig 7","restart(\"fig7\")")
xpanel(4,99)
}
objectvar scene_vector_[1]
{doNotify()}