Why is external concentration of ca2 1mM not 2mM?

[pgleeson]

To reproduce, type ca2o in the original NEURON code. cao is 2mM.

This code: https://github.com/OpenSourceBrain/SolinasEtAl-GolgiCell/blob/master/NEURON/Golgi_template.hoc#L86 may have been meant to set ca2o to 2mM, but setup of mechanisms in Nrn is tricky.

@theiera is it ok to change ca2o to 2mM?

@RokasSt this may have been the cause of some of the discrepancy with CaLVA in NML2...

[RokasSt]

I am using 2mM in NeuroML2, as NEURON is showing. See here
https://github.com/RokasSt/SolinasEtAl-GolgiCell/blob/master/NeuroML2/TestSoma.cell.nml

ca2o is set to 2mM.

I will check whether the NeuroML2 results of running the LVA channel will change with 1 mM.

@pgleeson
@theiera

[theiera]

This code: https://github.com/OpenSourceBrain/SolinasEtAl-GolgiCell/blob/master/NEURON/Golgi_template.hoc#L86 is
cai0_ca_ion = 50e-6
and it is correct.

I guess you meant: https://github.com/OpenSourceBrain/SolinasEtAl-GolgiCell/blob/master/NEURON/Golgi_template.hoc#L92
ca2o = cao

and cao should be 2 mM by default.

[RokasSt]

@pgleeson so we should keep using 2 mM

[pgleeson]

@theiera, yes that's the line that is supposed to set ca2o, but it doesn't (my link was to the general block where concentrations are set). A correct way to set the initial value of ca2 (which is an unrecognised ion; cao defaults to 2, all other unrecognised ions default to 1) is:

ca2o0_ca2_ion = 2

This will make sure ca2o is always 2.

Note changing ca2o to 2mM will change the behaviour of all NEURON examples slightly (spikes change ~0.5%) The options now are:

a) leave the error in place, put 1mM in the NML2 for ca2o & 2mM for cao
b) fix it in the NEURON, update the tests and visually check the graphs again