'RMT-Finder': an automated procedure to determine the Resting Motor Threshold for Transcranial Magnetic Stimulation

Details

Supervisors

Hardwick, Robert M. ; Moreno Verdu, Marcos

Faculty

Faculté de pharmacie et des sciences biomédicales

Degree label

Master [120] en sciences biomédicales, à finalité approfondie

Abstract

enBackground: Transcranial Magnetic Stimulation (TMS) experiments typically identify the Resting Motor Threshold (RMT) to calibrate stimulation intensity. This is often determined using ‘relative-frequency’ approaches; repeatedly testing a given intensity of stimulation, in % of Maximal Stimulator Output (% MSO), until it can be accepted or rejected as the RMT. However, this procedure is time-consuming and subject to considerable variability between laboratories. We aimed to develop an automated procedure for RMT determination to improve the efficiency and standardization of this critical step. Methods: We implemented a script based on a binary search algorithm which also controls the TMS device, automatically adjusting the stimulation intensity to determine the RMT. Experiment 1 compared this automated method with the conventional manual procedure in terms of reliability and equivalence. Experiment 2 developed a “Fast” automated process, reassessed it against both manual and the initial automated version, and compared the efficiency of each procedure. Results: Across both experiments the automated approach demonstrated excellent test-retest reliability and strong agreement with the manual method (Intraclass Correlation Coefficients ≥0.95), giving estimates of RMT equivalent to those of manual measurements within ±3% MSO, with the majority of comparisons within ±2% MSO. Experiment 2 optimized the procedure, allowing empirical determination of the RMT in an average of <3 minutes with only 33-34 pulses. Conclusions: The ‘RMT-Finder’ provides a reliable and time-efficient alternative to the traditional manual approach. This procedure can improve standardization and reproducibility in TMS studies and holds potential for clinical applications where rapid RMT determination is desirable.