Prediction of neural excitation during magnetic stimulation using passive cable models

A method for predicting neural excitation during magnetic stimulation using passive cable models has been developed. This method uses the information of the threshold capacitor voltage for magnetic stimulation coils to determ ine the equivalent excitation thresholds for the passive transient (PT) and passive steady-state (PSS) cable models as well as for the activating func tion. The threshold values for the PT, PSS models, and the activating funct ion vary only with the pulsewidth of the stimulus for a variety of coils at different locations and orientations, Furthermore, the excitation threshol d for the PSS model is also independent of axon diameter and best fitted to a simple mathematical Function, By comparing the transmembrane potential o f the PSS model with the corresponding threshold, the prediction of excitat ion during magnetic stimulation can be made, Similarly, it is also possible to predict excitation using the PT model and the activating function,vith the corresponding thresholds provided. By taking advantage of the weighted pulsewidth, this method can even predict the excitation for stimuli with va rious waveforms, greatly simplifying the determination of neural excitation for magnetic stimulation.