### Axial currents at branch points

Posted:

**Thu May 06, 2021 5:52 am**Hello,

I've been going through NEURON documentation and source code but the handling of axial current and the notion of breakpoint at branch points (mentionned in post "recording axial current") still remain really confusing for me.

Is there any difference between the handling of the axial current flowing between the segments of a single section and the one flowing between segments of two differents sections ?

Since in the Mathematical Basis of neuron it is said that in the particular case of a section with segments of equal size, the equation for axial current corresponds to the difference of potential with neighbors segments multiplied by the coefficient d/(4*ra*dx²) -> (in units of S/cm² if multiplied by 10^4) , I thought that it might be the equation used for currents between segments in a section. However when looking in the source code it looks like all coefficients for axial currents are based the on the calculation of Ri,j and the area of parent/child node (to convert in density of current).

I've been going through NEURON documentation and source code but the handling of axial current and the notion of breakpoint at branch points (mentionned in post "recording axial current") still remain really confusing for me.

Is there any difference between the handling of the axial current flowing between the segments of a single section and the one flowing between segments of two differents sections ?

Since in the Mathematical Basis of neuron it is said that in the particular case of a section with segments of equal size, the equation for axial current corresponds to the difference of potential with neighbors segments multiplied by the coefficient d/(4*ra*dx²) -> (in units of S/cm² if multiplied by 10^4) , I thought that it might be the equation used for currents between segments in a section. However when looking in the source code it looks like all coefficients for axial currents are based the on the calculation of Ri,j and the area of parent/child node (to convert in density of current).