Closed-form expressions for the directions of maximum modulation depth in temporal interference electrical brain stimulation.

The preprint operates within the dominant paradigm of bioelectromagnetism, specifically focusing on the use of electric fields for neuromodulation. It uses established methodologies of computational bioelectromagnetism to analyze and model electric fields interaction with neural tissue.

The preprint primarily contributes to "normal science" by refining existing models and mathematical tools within the established paradigm of temporal interference electrical brain stimulation (TI EBS). It provides a novel closed-form analytical expression for the orientation of maximum modulation depth, which is a valuable contribution to the existing theory, but it not challenging or introducing any new fundamental concepts to the field.

However, the findings related to the secondary maximum modulation depth and its potential comparable strength to the primary maximum, especially when electric field vectors are misaligned, could potentially lead to a “model drift”. This highlights a previously unnoticed aspect of TI stimulation that could have implications for optimizing and interpreting the results of TI EBS. It suggests a possible refinement or adjustment of the existing models to account for this secondary maximum and its influence on neuromodulation outcomes. While not a "model crisis" yet, this finding warrants further investigation and could lead to adjustments in current practices or assumptions about TI EBS.

Given the above, classifying this preprint as purely “normal science” or “model drift” is difficult. The work is refining current models and providing new tools which fits "normal science" but these refinements also bring to light previously unknown implications, pointing towards "model drift."
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