Setting default reversal potential for an ionic species
Posted: Sun Nov 17, 2013 4:37 pm
Hello,
I am very new to NEURON and have a basic question. Specifically, I am wondering if there is a way to specify the default reversal potential for an ionic species, for example, potassium, such that all ion channels that use this ion will have the same default reversal potential.
The one way I have found to set the reversal potential is to specify it when defining the section, as in
However, one has to do this for every section, which can be cumbersome. I notice that, if ek=-89.1 is not specified, the ek value will default to -77. Ideally, one way to accomplish what I am asking would be to change this default value, but I am not sure how to access it.
The other method I have been attempting is to specify a default value in the mod file. For example, I noticed that the Neuron example script "nrn/nrn/share/examples/nrniv/nmodl/hh1.mod" contains lines in the PARAMETER section attempting to set the default ek and ena values
However, when I ran this code, psection() returned the default value of -77 mV, and not -77.5 mV, so it seems that this segment of the code is overridden by the default (I guess perhaps there is some lower-level process for calculating the reversal potential?).
So, in short, it would be great if someone could suggest a more elegant mechanism for dealing with this. As a back up plan, I will just specify a global variable to use to hold the reversal potential.
Thank you!
I am very new to NEURON and have a basic question. Specifically, I am wondering if there is a way to specify the default reversal potential for an ionic species, for example, potassium, such that all ion channels that use this ion will have the same default reversal potential.
The one way I have found to set the reversal potential is to specify it when defining the section, as in
Code: Select all
soma {
nseg = 1
diam = 18.8
L = 18.8
Ra = 123.0
insert hh
ena = 71.5
ek = -89.1
gnabar_hh=0.25
gl_hh = .0001666
el_hh = -60.0
insert CaT
eca = 126.1
}
The other method I have been attempting is to specify a default value in the mod file. For example, I noticed that the Neuron example script "nrn/nrn/share/examples/nrniv/nmodl/hh1.mod" contains lines in the PARAMETER section attempting to set the default ek and ena values
Code: Select all
PARAMETER {
v (mV)
celsius = 6.3 (degC)
dt (ms)
gnabar = .12 (mho/cm2)
ena = 50 (mV)
gkbar = .036 (mho/cm2)
ek = -77.5 (mV)
gl = .0003 (mho/cm2)
el = -54.3 (mV)
}
So, in short, it would be great if someone could suggest a more elegant mechanism for dealing with this. As a back up plan, I will just specify a global variable to use to hold the reversal potential.
Thank you!