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External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures
Published on: May 7, 2017
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Single pointwise samples of electric field on a neuron model cannot predict activation threshold by brain stimulation
Biorxiv : the Preprint Server for Biology
|August 6, 2025
Summary
Computational models for transcranial magnetic stimulation (TMS) often overestimate electric field (E-field) thresholds. This study shows neural activation depends on spatial E-field integration, not single points, making microscopic perturbations negligible.
Area of Science:
- Neuroscience
- Computational Biology
- Biophysics
Background:
- Computational models of transcranial magnetic stimulation (TMS) can overestimate electric field (E-field) thresholds compared to in vivo data.
- A recent statistical method assumes E-field thresholds depend on single pointwise samples, which is unsubstantiated.
Purpose of the Study:
- To analyze neural responses to E-fields with microscopic perturbations.
- To demonstrate that neural activation relies on spatial E-field integration along neural cables, not pointwise amplitude.
- To show the negligible influence of microscopic E-field perturbations due to neural filtering.
Main Methods:
- Derivation of axial and transmembrane currents in neural cables subjected to perturbed E-fields.
- Simulation of neural activation thresholds for unmyelinated and myelinated axons under different stimulation scenarios.
- Comparison of activation thresholds with and without E-field spatial perturbations.
Main Results:
- Theoretical derivation shows perturbation terms average to zero on larger scales, not affecting neural activation thresholds.
- Simulations revealed negligible differences (<3.4%) in thresholds with E-field spatial perturbations compared to their absence.
- Microscopic E-field perturbations do not significantly alter neural activation thresholds.
Conclusions:
- Pointwise E-field samples are insufficient for predicting neural activation thresholds.
- Neural simulations are necessary to accurately determine the influence of E-field spatial perturbations.
- E-field spatial perturbations are unlikely to explain discrepancies between experimental and simulated TMS E-field thresholds.
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