Hi all
I am very new to Neuron, so apologies if I am asking a stupid question.
Does anyone know of a way to specify a finite volume of extracellular fluid?
Thanks
Rob
Specifying a finite volume of Extracellular fluid
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Re: Specifying a finite volume of Extracellular fluid
You want a model of ion accumulation in extracellular space. Doable with NMODL, for example see the implementation of Frankenhaeuser-Hodgkin space in chapter 9 of The NEURON Book. For your convenience, I reproduce kext.mod here
An aside: astute readers may notice that the METHOD is now derivimplicit rather than cnexp. derivimplicit is appropriate for ion accumulation mechanisms specified by ODEs and will work regardless of the equilibration time constant.
Code: Select all
: Extracellular potassium ion accumulation
: fhspace and kxfer are from Frankenhaeuser & Hodgkin
NEURON {
SUFFIX kext
USEION k READ ik WRITE ko
GLOBAL kbath
RANGE fhspace, txfer
}
UNITS {
(mV) = (millivolt)
(mA) = (milliamp)
FARADAY = (faraday) (coulombs)
(molar) = (1/liter)
(mM) = (millimolar)
}
PARAMETER {
kbath = 2.5 (mM)
: Frankenhaeuser-Hodgkin space parameters
fhspace = 300 (angstrom) : thickness
txfer = 50 (ms) : fhspace <-> bath transfer time
}
ASSIGNED {
ik (mA/cm2)
}
STATE {
ko (mM)
}
BREAKPOINT {
SOLVE state METHOD derivimplicit
}
DERIVATIVE state {
ko' = (1e8)*ik/(fhspace*FARADAY) + (kbath - ko)/txfer
}
Re: Specifying a finite volume of Extracellular fluid
Thanks Ted
I will have a good look at the relevant sections in the NEURON book.
Rob
I will have a good look at the relevant sections in the NEURON book.
Rob