How can plug-ins influence an ionic model?

Question

Hello, 

I was recently wondering how plug-ins can affect Ionic models and, in particular, which parts of the Ionic model plug-ins can influence. If you look at most of the plug-ins in openCARP, the most obvious answer is clear: plug-ins can modify Iion externally via something like: Iion += some_variables; These can be other equations calculating currents inside the plug-in code, constants, parameters or the transmembrane voltage. 

Is it also possible to modify other variables in a similar way, and what are the prerequisites or limitations involved?

Answer 1

In addition to Iion, various other variables can be modified externally via a plug-in. In general, any variables that can be defined as external(); nodal(); can be modified via a plug-in. These variables can be found at the end of the file imp_list.txt in the physics/limpet/models folder. Unlike the simple modification of Iion, it is important to explicitly multiply the equation by the time step used if the variable is integrated within the ODE system of the ion model. 

As an example for Ki, this might mean that we have the implementation of changes to Ki via the normal diff_Ki equation within the ion model and we would need to add Ki -= 1e-3 * some_variables; where 1e-3 is the time step.