title: Minimum number of trials required for within- and between-session reliability of TMS measures of corticospinal excitability.
abstract: Transcranial magnetic stimulation (TMS)-elicited motor-evoked potentials (MEPs) exhibit considerable trial-to-trial variability, potentially reducing the sensitivity and reproducibility of this measure. While increasing the number of trials will improve accuracy, prolonged recording blocks are not always feasible. In this study, we investigated the minimum number of trials required to provide a measure of human corticospinal excitability that is stable both within and between sessions. Single-pulse TMS was applied to the left primary motor cortex, and MEPs were recorded from the right first dorsal interosseous muscle. Approximately 20-30 trials were required to provide a stable measure of MEP amplitude with high within- and between-session reliability. Extending the number of trials beyond 30 provided no additional benefit. Collecting 30 trials may be optimal for reliably estimating corticospinal excitability using TMS. These findings may have significant implications for using TMS to measure corticospinal excitability in both basic and clinical research settings.
authors.affiliation: Robinson Research Institute, School of Medicine, University of Adelaide, Adelaide 5005, Australia. Electronic address: mitchell.goldsworthy@adelaide.edu.au.
authors.forename: M R
authors.initials: MR
authors.lastname: Goldsworthy
authors.affiliation: Robinson Research Institute, School of Medicine, University of Adelaide, Adelaide 5005, Australia.
authors.forename: B
authors.initials: B
authors.lastname: Hordacre
authors.affiliation: Robinson Research Institute, School of Medicine, University of Adelaide, Adelaide 5005, Australia.
authors.forename: M C
authors.initials: MC
authors.lastname: Ridding
mesh_terms: D000293:Adolescent; D000328:Adult; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011712:Pyramidal Tracts; D015203:Reproducibility of Results; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: between-session reliability; motor-evoked potential; primary motor cortex; transcranial magnetic stimulation; within-session reliability