{"doi":"10.1016/j.brs.2023.11.009","title":"Correlating active and resting motor thresholds for transcranial magnetic stimulation through a matching model","abstract":"Dear Editor, Transcranial magnetic stimulation (TMS) can relatively focally elicit action potentials in cortical neurons in the brain. Sufficiently strong pulses over the primary motor cortex can trigger cortico-spinal output signals leading to measurable motor-evoked potentials (MEPs) and even visually detectable muscle twitches [[1]Goetz SM, Alavi SMM, Deng ZD, and Peterchev AV. Statistical Model of Motor-Evoked Potentials. IEEE Transactions on Neural Systems and Rehabilitation Engineering 2019; 27:1539–1545.Google Scholar]. The motor threshold (i.e., expressed as a percentage of the maximum stimulator output) as an indirect indicator of the motor cortex excitability represents the lowest stimulus strength that evokes a MEP with an amplitude around 50 μV at rest (resting motor threshold, RMT) and of around 200 μV during voluntary contraction of the tested muscle (active motor threshold, AMT) [2Rossini PM, Burke D, Chen R, Cohen L, Daskalakis Z, Di Iorio R, et al. Non-invasive electrical and magnetic stimulation of the brain, spinal cord, roots and peripheral nerves: Basic principles and procedures for routine clinical and research application. An updated report from an IFCN Committee. Clinical neurophysiology 2015; 126:1071–1107.Google Scholar, 3Wang B, Peterchev AV, and Goetz SM. Three novel methods for determining motor threshold with transcranial magnetic stimulation outperform conventional procedures. Journal of Neural Engineering 2023; 20:056002.Google Scholar]. The AMT enhances both spinal and cortical excitability in the primary motor cortex through voluntary muscle contraction for higher sensitivity of the neural circuits and therefore typically leads to lower values than the RMT [[4]Lazzaro VD, Restuccia D, Oliviero A, Profice P, Ferrara L, Insola A, et al. Effects of voluntary contraction on descending volleys evoked by transcranial stimulation in conscious humans. The Journal of physiology 1998; 508:625–633.Google Scholar]. The motor threshold serves as the main metric for individualising the pulse strength in neuromodulation for both experimental brain research and clinical trails [2Rossini PM, Burke D, Chen R, Cohen L, Daskalakis Z, Di Iorio R, et al. Non-invasive electrical and magnetic stimulation of the brain, spinal cord, roots and peripheral nerves: Basic principles and procedures for routine clinical and research application. An updated report from an IFCN Committee. Clinical neurophysiology 2015; 126:1071–1107.Google Scholar, 5Pridmore S, Fernandes Filho JA, Nahas Z, Liberatos C, and George MS. Motor threshold in transcranial magnetic stimulation: a comparison of a neurophysiological method and a visualization of movement method. The journal of ECT 1998; 14:25–27.Google Scholar]. Additionally, the motor threshold is the reference pulse strength for practically all safety recommendations and limits [[6]Rossi S, Antal A, Bestmann S, Bikson M, Brewer C, Brockmöller J, et al. Safety and recommendations for TMS use in healthy subjects and patient populations, with updates on training, ethical and regulatory issues: Expert Guidelines. Clinical Neurophysiology 2021; 132:269–306.Google Scholar]. Whereas repetitive TMS with fixed pulse rhythms is typically based on the RMT, patterned pulse protocols, such as theta-burst stimulation, preferably use the lower AMT as a reference stimulation strength [[7]Turi Z, Lenz M, Paulus W, Mittner M, and Vlachos A. Selecting stimulation intensity in repetitive transcranial magnetic stimulation studies: A systematic review between 1991 and 2020. European Journal of Neuroscience 2021; 53:3404–3415.Google Scholar]. However, it was found that the outcome of theta-burst stimulation does not only depend on the TMS pulse strength but also muscle pre-activation before the neuromodulatory intervention—which obviously is an inherent part of the AMT detection procedure [8Gentner R, Wankerl K, Reinsberger C, Zeller D, and Classen J. Depression of human corticospinal excitability induced by","journal":"Brain stimulation","year":2023,"id":345332,"datarank":0.3958585994422889,"base_score":2.639057329615259,"endowment":2.639057329615259,"self_citation_contribution":0.3958585994422889,"citation_network_contribution":0.0,"self_endowment_contribution":0.3958585994422889,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":13,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9578,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2023-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1084811,"name":"Masashi Hamada","orcid":"0000-0002-2866-8067","position":1,"is_corresponding":false},{"id":106042,"name":"Vincenzo Di Lazzaro","orcid":"0000-0002-9113-5925","position":2,"is_corresponding":false},{"id":1084812,"name":"Brodie J. Hand","orcid":"0000-0002-9778-343X","position":3,"is_corresponding":false},{"id":1084813,"name":"Andrea Guerra","orcid":"0000-0001-6601-4964","position":4,"is_corresponding":false},{"id":1084814,"name":"George M. Opie","orcid":"0000-0001-7771-7569","position":5,"is_corresponding":false},{"id":1085315,"name":"Stephan M. Goetz","orcid":null,"position":6,"is_corresponding":false},{"id":1084810,"name":"Ke Ma","orcid":"0000-0002-8499-4529","position":0,"is_corresponding":true}],"reference_count":13,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T01:11:39.484741Z","pmid":"37992891","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}