Consider we have two sections soma and dend and connect them in the following way: connect dend(0),soma(0).
If I print the axial resistance (ri) at soma(0) and dend(0) it says 1e30. Does it mean that there is no flow of current between these points ?
Axial currents between two compartments
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Re: Axial currents between two compartments
What does the documentation of ri() say about this?shyam_u2 wrote:If I print the axial resistance (ri) at soma(0) and dend(0) it says 1e30.
What does the documentation of connect suggest? What do you discover by using a model designed to disambiguate this issue?Does it mean that there is no flow of current between these points ?
Re: Axial currents between two compartments
The documentation of 'ri' says that it returns the resistance (in megohms) between the center of the segment containing x and its parent segment. First of all, I don't understand how NEURON computes the parent segment of a section. How could the resistance at the point of connect between soma and dend could be infinite (since they are connected) ? I also found that ri at soma(0) is always infinite no matter whether I connect the 0 or 1 end of the dendrite.
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Re: Axial currents between two compartments
Consider this example:shyam_u2 wrote:I don't understand how NEURON computes the parent segment of a section.
Code: Select all
oc>create soma, dend
oc>access soma
oc>connect dend(0), soma(1)
oc>topology()
|-| soma(0-1)
`| dend(0-1)
Code: Select all
oc>forall { L = 100 diam = 1 }
oc>forall for (x) print secname(), " ", ri(x)
first instance of x
soma 1e+30
soma 22.53634
soma 22.53634
dend 22.53634
dend 22.53634
dend 22.53634
dend 22.53634
is no surprise because you realize that dend(0) refers to the same node as soma(1) and therefore its parent node is soma(0.5).
Now attach a new section to the 0 end of soma.
Code: Select all
oc>create axon
oc>connect axon(0), soma(0)
oc>topology()
|-| soma(0-1)
`| dend(0-1)
`| axon(0-1)
1
oc>axon { L = 100 diam = 1 }
oc>forall for (x) print secname(), " ", ri(x)
soma 1e+30
soma 22.53634
soma 22.53634
dend 22.53634
dend 22.53634
dend 22.53634
axon 1e+30
axon 22.53634
axon 22.53634
axon print ri(0)
returns 1e+30.
That's not the meaning of the value returned by ri(0) when the currently accessed section is axon.How could the resistance at the point of connect between soma and dend could be infinite
That's as it should be if soma is the root section.ri at soma(0) is always infinite no matter whether I connect the 0 or 1 end of the dendrite.