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

 Download zip file   Auto-launch 
Help downloading and running models
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(3):1127-33 [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): Neocortex V1 L6 pyramidal corticothalamic 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 cell; I K; I Calcium;
/
SpaceClampDemo
cells
ReadMe.html
calcium.mod
potassium.mod
calcium.hoc
init.hoc
mosinit.hoc *
potassium.hoc
screenshot.jpg
                            
COMMENT

gBoltzT.mod

ENDCOMMENT

INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}

NEURON {
	SUFFIX Potassium
	USEION k READ ek WRITE ik
	RANGE n, gk, gbar, ninf, nexp
	GLOBAL v12, vSlope, tau
}

UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
	(pS) = (picosiemens)
	(um) = (micron)
} 

PARAMETER {
	gbar = 150   	(pS/um2)	: 0.03 mho/cm2
	v 		(mV)
								
	v12 = -17.3	(mV)
	vSlope = 11.3	(mV)
	tau = 3
} 


ASSIGNED {
	ik 		(mA/cm2)
	gk		(pS/um2)
	ek		(mV)
	ninf
	nexp
}
 

STATE { n }

INITIAL { 
	states()
	
}

BREAKPOINT {
        SOLVE states
	gk = gbar*n
	ik = (1e-4) * gk * (v - ek)
} 

PROCEDURE states() {   : Computes state variable n 

	nexp = 1-exp(-dt/tau)
	ninf = 1/(1+exp(-(v-v12)/vSlope))
	n = n + nexp*(ninf-n)
}

Loading data, please wait...