Writing fluxes between mechanisms?

[wthun]

We (@Hjorthmedh) want to link values between different mechanisms. The use case is to write fluxes, e.g. to have several reaction modules coupled to a central buffer that writes the concentration to the membrane after summating the fluxes, or write fluxes from synapses to a compartment. Our initial idea was to use nmodl:s POINTER, but this seems to not be supported by Arbour. Any other options?

[thorstenhater]

Hi @wthun and @Hjorthmedh,

sorry for the delay, Arbor was on summer break for the last two weeks enjoying the beach 🏖️
You're correct, POINTER isn't allowed by Arbor, so you need to explore other options. Here's
what I can think of right now, without further insight into the concrete problem

1. Combine all relevant processes. This is neither scalable nor flexible, but might suffice for very simple assemblies.
2. Use the diffusion support, it offers another ionic concentration (Xd) that is persistent across steps (opposed to Xi), and set a low diffusivity.

[wthun]

Thanks for the suggestions. Am I correct in reading the documentation right that multiple mechanisms can write Xd on the same location?

Also, without pointers, how could I couple the influx of X to a synaptic event?

[thorstenhater]

Yes, multiple writers are allowed, as long as the updates are order-independent.

For an example refer to this mechanism: mechanisms/default/inject.mod