A question about USEION statement

NMODL and the Channel Builder.
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doctorxue
Posts: 2
Joined: Tue Feb 27, 2018 10:54 pm

A question about USEION statement

Post by doctorxue » Mon Aug 13, 2018 11:42 am

Hello everyone:

I'm now trying to model a ion channel that is selective. The USEION statement causes some confusion. There're absolutely many kind of channels that are selective for one ion, and in every NMODL file we write USEION x READ...WRITE ix, to calculate the ion-specific current. Finally there is a diffusion mechanism to model its instant impact on extracellular concentration and this needs to READ the ion-specific current.

I would like to know that when NEURON is running and calculating for every segment, will ix of different NMODL channels override each other after every calculation? Or NEURON treat ix from different NMODL channels independently and sum them together automatically? If possible I would like to know how NEURON treat USEION statement in different NMODL files.

I appreciate your kindness if you can give any suggestion on this topic!


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Yao

ramcdougal
Posts: 138
Joined: Fri Nov 28, 2008 3:38 pm
Location: Yale School of Medicine

Re: A question about USEION statement

Post by ramcdougal » Mon Aug 13, 2018 1:06 pm

Currents of the same type from different mechanisms add.

You can test this yourself by creating two trivial mod files that generate a constant current, and measuring the current when one vs both are inserted.

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