Hello,
I'm a very new user of NEURON. I guess my question is very simple for you. However, I confused a little by looking at NEURON book and some available online codes
do we have to define number of segments before inserting any type of channel density or after that?
specifying nseg and channel density
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Re: specifying nseg and channel density
As a rule, it's good to get in the habit of specifying nseg first, and specifying channel density second.
If you want channel density to be uniform, it doesn't matter which you do first.
Example: try thisthen try again but this time set g_pas before setting nsegand you'll see that the final result is the same.
If you want nonuniform channel density, every time you specify a new value of nseg you should follow that by applying the rule that governs channel density.
Example: try this
If you want channel density to be uniform, it doesn't matter which you do first.
Example: try this
Code: Select all
create dend
access dend
insert pas
nseg = 3
g_pas = 1
for (x,0) print x, g_pas
Code: Select all
. . .
g_pas = 1
nseg = 3
for (x,0) print x, g_pas
If you want nonuniform channel density, every time you specify a new value of nseg you should follow that by applying the rule that governs channel density.
Example: try this
Code: Select all
create dend
access dend
insert pas
nseg = 3
// suppose you want g_pas to be a linear function of position in dend
for (x,0) g_pas(x) = 0.1*x
for (x,0) print x, g_pas(x) // three segments, so three different values of g_pas
print " "
// suppose you want g_pas to vary more smoothly along the length of dend
nseg *= 3 // make nseg 3 times larger
for (x,0) print x, g_pas(x) // 9 segments but only 3 different values of g_pas!
// no improvement of smoothness!
print " "
// you need to specify g_pas as a function of x again
for (x,0) g_pas(x) = 0.1*x
for (x,0) print x, g_pas(x) // much smoother
Re: specifying nseg and channel density
Hi Ted,
Thanks a lot for your prompt response. I really appreciate it.
Thanks a lot for your prompt response. I really appreciate it.
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- Site Admin
- Posts: 6299
- Joined: Wed May 18, 2005 4:50 pm
- Location: Yale University School of Medicine
- Contact:
Re: specifying nseg and channel density
You're welcome. Thanks for using NEURON in your research.