Space clamp problems in neurons with voltage-gated conductances (Bar-Yehuda and Korngreen 2008)

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Accession:110560
" ... using numerical simulations, we show that the distortions of voltage-gated K+ and Ca2+ currents are substantial even in neurons with short dendrites. The simulations also demonstrate that passive cable theory cannot be used to justify voltage-clamping of neurons, due to significant shunting to the reversal potential of the voltage-gated conductance during channel activation. ... "
Reference:
1 . Bar-Yehuda D, Korngreen A (2008) Space-clamp problems when voltage clamping neurons expressing voltage-gated conductances. J Neurophysiol 99:1127-36 [PubMed]
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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): Neocortex V1 L6 pyramidal corticothalamic GLU cell;
Channel(s): I K; I Calcium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Ion Channel Kinetics; Influence of Dendritic Geometry; Detailed Neuronal Models;
Implementer(s): Korngreen, Alon [alon.korngreen at gmail.com];
Search NeuronDB for information about:  Neocortex V1 L6 pyramidal corticothalamic GLU cell; I K; I Calcium;
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SpaceClampDemo
cells
ReadMe.html
calcium.mod
potassium.mod
calcium.hoc
init.hoc
mosinit.hoc *
potassium.hoc
screenshot.jpg
                            
// init.hoc loads a potassium cell by default into NEURON for
// potential use by ModelView but then allows a restart with any model

create soma
access soma

membranecap = 1    /* specific membrane capacitance in uF cm^-2 */
membraneresist = 40000 /* specific membrane resistance in ohm cm^2 */
axialresist = 100     /* axial resistivity in ohm cm */
Vrest = -70               /* resting potential, mV */
EK=-90
Gbar=20
V05=-10
Z=10


objref gplot, vplot, vC,BOX

proc load_cell() {

// $s1 filename

  aspiny = 0
  forall delete_section()
  xopen($s1)
  access soma
	forall {
		nseg*=5
		insert pas
		insert Potassium
		gbar_Potassium=Gbar
		v12_Potassium=V05
		vSlope_Potassium=Z
		tau_Potassium=3
		e_pas = Vrest
		ek= EK
		g_pas=1/membraneresist 
		Ra=axialresist 
		cm=membranecap
	}
	soma  vC = new SEClamp(0.5)
	vC.amp1=-120
	vC.dur1=15400
	vC.amp2=0
	vC.dur2=1000

	vC.rs=1e-5
 }   

// default loading of potassium L5 pyr model for ModelView
// then supply choice for modeler

load_cell("cells/A0606.hoc")

xpanel("Choose K or Ca simulations")
xbutton("Potassium conductance density", "xopen(\"potassium.hoc\")")
xbutton("Calcium conductance density", "xopen(\"calcium.hoc\")")
xpanel()