no accessed section:can't start an electrode

[GTR]

Problem again.
In a folder I had the compiled .mod files together with some session files that I had saved containing the characteristics of the neuron I want to simulate (cell builder:geometry,subsets,biophysics etc).
I made some modifications in my Na.mod and NaP.mod files -I changed the form of currents -and nrnmech.dll was built successfully again but when I doubleclicked to an existing session file within the same folder named STN I get the following message error:

nrniv: gNabar_NaP not in this property
in C:/STN/CompleteSTN.hoc near line 488
}
^
MechanismStandard[0].set"gNabar_NaP"1e-070.

I acknowledge that now I have an new .dll mechanism but I hoped that opening again the .hoc file,modified NMODL channels would have been loaded normally in the cell builder.

Nevertheless,with a new nrngui and the additional NMODL mechanisms from files loaded in the new cellbuilder I tried to build again the .ses neuron model within the same folder and to open it.
But when I tried to implement point processes and place an electrode in my neuron I got the warning:
no accessed section:can't start an electrode

Moreover I tried to simulate the resting state of my neuron with a simple RunControl and a voltage graph window but now I read from the hoc interpreter:
oc>Graph:: presently invalid expression: v(.5)

Does the last two messages come from the same source of problem?What can I do to fix it?

Regards,
George.

[ted]

That's very odd. Your hoc and ses files worked fine (reconstituted the model correctly)
before you changed the NMODL code? If so, this

nrniv: gNabar_NaP not in this property

suggests that the NaP mechanism's NEURON block no longer declares gNabar.

Does the last two messages come from the same source of problem?

Yes: there is no default section. Many GUI tools, such as the Point Process Manager,
do not work if there is no default section. The voltage axis graph comes up with v(.5) in
its plot list, and of course if there is no default section, there is no variable called v(.5).

In asking this question, I assume that you are not working with the Network Builder:
is there a check mark in the Cell Builder's Continuous Create box? If not, click on it to
turn Continuous Create on (the check mark should appear) and save a new session file,
then exit NEURON. Start again, and things should work fine.