When you provide multiple EM-LF simulations as sources to the Neuron solver, the neuron effectively receives the sum of the extracellular fields/potentials generated by the individual simulations (assuming the same modulation pulse is used). This is expected behavior because EM-LF simulations are linear, and therefore their solutions can be superimposed.
To verify this behavior, you can use the Field Combiner tool in Sim4Life:
First, combine the EM-LF results using the Field Combiner, which applies linear superposition of the fields.
Then, use the combined field as a single source for the Neuron simulation.
If you compare this setup to a Neuron simulation where the individual EM-LF results are used as separate sources (with the same modulation pulse), the neuron response will be identical.
This confirms that, internally, the Neuron solver is operating on the sum of the fields from the different EM-LF simulations.
If additional verification is desired, the EM-LF fields can also be interpolated along the neuron spline (for each simulation individually and for the Field Combiner result) to explicitly confirm that the combined field corresponds to the pointwise sum of the individual fields.
Note: the field combiner expects the fields to be at the same frequency.
If you would like more information about a specific application, or if you would like to share your project with us to receive more targeted feedback, please do not hesitate to contact us at s4l-support@zmt.swiss.
