Submyelin Potassium accumulation in Subthalamic neuron (STN) axons (Bellinger et al. 2008)

 Download zip file   Auto-launch 
Help downloading and running models
Accession:121253
"To better understand the direct effects of DBS (Deep brain stimulation) on central neurons, a computational model of a myelinated axon has been constructed which includes the effects of K+ accumulation within the peri-axonal space. Using best estimates of anatomic and electrogenic model parameters for in vivo STN axons, the model predicts a functional block along the axon due to K+ accumulation in the submyelin space. ... These results suggest that therapeutic DBS of the STN likely results in a functional block for many STN axons, although a subset of STN axons may also be activated at the stimulating frequency. "
Reference:
1 . Bellinger SC, Miyazawa G, Steinmetz PN (2008) Submyelin potassium accumulation may functionally block subsets of local axons during deep brain stimulation: a modeling study. J Neural Eng 5:263-74 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Axon;
Brain Region(s)/Organism:
Cell Type(s): Subthalamus nucleus projection neuron;
Channel(s): I Na,p; I K; I Sodium; I_Ks; Na/K pump;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Axonal Action Potentials; Action Potentials; Deep brain stimulation; Sodium pump; Depolarization block;
Implementer(s): Bellinger, Steven [Steve.Bellinger at asu.edu];
Search NeuronDB for information about:  I Na,p; I K; I Sodium; I_Ks; Na/K pump;
COMMENT
Longitudinal and radial diffusion of potassium
ENDCOMMENT

NEURON {
	SUFFIX kdifrl
	USEION k READ ik WRITE ko
	RANGE ko, Dk, sp
}

UNITS {
  	(molar) = (1/liter)
  	(mM) = (millimolar)
	(um) = (micron)
	(mA) = (milliamp)
	FARADAY = (faraday) (coulomb)
	PI = (pi) (1)
}

PARAMETER {
	Dk = 1.85 (um2/ms)
	nodalGap = 1.9 (um)
	rn = 0.95 (um)
	extracellularVolumePerLength (um2)
	crossSectionalArea (um2)
	kbathVolumePerLength = 1e15 (um2)
	radialCrosssectionalAreaPerLength (um)
	radialRateConstant (um2/ms)
	kbath = 3 (mM)
}

ASSIGNED { ik (mA/cm2) }

STATE { ko (mM) }

INITIAL {
	extracellularVolumePerLength =PI * ( (rn+nodalGap)^2 - rn^2 )
	crossSectionalArea = extracellularVolumePerLength

	radialCrosssectionalAreaPerLength = 2 * PI * ( rn + nodalGap )
	radialRateConstant = Dk * radialCrosssectionalAreaPerLength / nodalGap
}

BREAKPOINT { SOLVE conc METHOD sparse }

KINETIC conc {
	COMPARTMENT crossSectionalArea { ko }
	COMPARTMENT kbathVolumePerLength { kbath }
	LONGITUDINAL_DIFFUSION Dk*extracellularVolumePerLength { ko }
	~ ko << (ik/(FARADAY)*2*PI*rn*(1e4))
	~ ko <-> kbath (radialRateConstant,radialRateConstant)
}

Loading data, please wait...