{"doi":"10.1016/j.brs.2021.06.012","title":"Four electric field modeling methods of Dosing Prefrontal Transcranial Magnetic Stimulation (TMS): Introducing APEX MT dosimetry","abstract":"•Electric field (E-field) TMS dosing is an emerging approach, but is not yet optimized or widely adopted.•Here we propose four methods of E-field TMS dosing, including APEX MT.•Motor threshold and fixed threshold E-field dosing had large motor vs. prefrontal E-field variances of 16.9-20.7%.•APEX MT combines motor threshold and E-field modeling to more optimally dose prefrontal TMS.•APEX MT reduced the within-subject motor vs. prefrontal E-field variance to 0%. We recently performed electric field (E-field) modeling on 38 structural magnetic resonance imaging (MRI) scans in the motor and prefrontal cortices to reexamine the widely used 120% resting motor threshold (rMT) dosing technique(1). Using the finite element method (FEM) to simulate electromagnetic currents passing through tissues with different conductivities (i.e. skin, bone, cerebrospinal fluid, grey matter, and white matter) [[2]Saturnino G.B. Puonti O. Nielsen J.D. Antonenko D. Madsen K.H. Thielscher A. SimNIBS 2.1: a comprehensive pipeline for individualized electric field modelling for transcranial brain stimulation.in: Makarov S. Horner M. Noetscher G. Brain and hum bod model 2018. Springer Copyright, Cham (CH)2019: 3-25Crossref Google Scholar], we found that TMS would need to be applied at an average of 133.5% of resting motor threshold (rMT) over the left prefrontal cortex to produce equivalent E-fields as 100% rMT stimulation over the left primary motor cortex, with large interindividual variability (range = 79.9–247.5% rMT) [[1]Caulfield K.A. Li X. George M.S. A reexamination of motor and prefrontal TMS dosing in tobacco use disorder: time for personalized electric field TMS dosing?.Clin Neurophysiol. 2021; Crossref Scopus (1) Google Scholar]. E-field dosing may be a useful method of reducing cortical E-field variations([3Caulfield K.A. Badran B.W. DeVries W.H. Summers P.M. Kofmehl E. Li X. et al.Transcranial electrical stimulation motor threshold can estimate individualized tDCS dosage from reverse-calculation electric-field modeling.Brain Stimul. 2020; 13: 961-969Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar, 4Caulfield K.A. Badran B.W. Li X. Bikson M. George M.S. Can transcranial electrical stimulation motor threshold estimate individualized tDCS doses over the prefrontal cortex? Evidence from reverse-calculation electric field modeling.Brain Stimul. 2020; 13: 1150-1152Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar, 5Caulfield K.A. Indahlastari A. Nissim N.R. Lopez J.W. Fleischmann H.H. Woods A.J. et al.Electric field strength from prefrontal transcranial direct current stimulation determines degree of working memory response: a potential application of reverse-calculation modeling?.Neuromodulation. 2020; Crossref Scopus (7) Google Scholar, 6Gomez L.J. Dannhauer M. Koponen L.M. Peterchev A.V. Conditions for numerically accurate TMS electric field simulation.Brain Stimul. 2020; 13: 157-166Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar, 7Deng Z.-D. Liston C. Gunning F.M. Dubin M.J. Fridgeirsson E.A. Lilien J. et al.Electric field modeling for transcranial magnetic stimulation and electroconvulsive therapy. Brain and hum bod model. Springer, Cham2019: 75-84Google Scholar]). However, there is currently no widely adopted E-field dosing approach or consensus on the optimal E-field dosing threshold. Here we investigate four E-field modeling methods that could be used to prospectively dose prefrontal TMS, demonstrating the benefits and drawbacks of each approach through modeling on our 38 previously acquired scans [[8]Li X. Hartwell K.J. Henderson S. Badran B.W. Brady K.T. George M.S. Two weeks of image-guided left dorsolateral prefrontal cortex repetitive transcranial magnetic stimulation improves smoking cessation: a double-blind, sham-controlled, randomized clinical trial.Brain Stimul. 2020; 13: 1271-1279Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar](Fig. 1A–D; Supplementary Sectio","journal":"Brain stimulation","year":2021,"id":163925,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":40,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9608,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":289791,"name":"Xingbao Li","orcid":"0000-0002-3284-9047","position":1,"is_corresponding":false},{"id":106043,"name":"Mark S. George","orcid":"0000-0003-1767-1815","position":2,"is_corresponding":false},{"id":289790,"name":"Kevin A. Caulfield","orcid":"0000-0001-8268-4204","position":0,"is_corresponding":true}],"reference_count":10,"raw_metadata":null,"created_at":"2026-07-18T23:45:27.031465Z","pmid":"34186248","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":[]}