{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,29]],"date-time":"2026-10-29T23:34:36Z","timestamp":1793316876814,"version":"4.5.0"},"reference-count":50,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2024,6,27]],"date-time":"2024-06-27T00:00:00Z","timestamp":1719446400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Bioeng. Biotechnol."],"abstract":"<jats:sec><jats:title>Introduction<\/jats:title><jats:p>Functional electrical stimulation (FES) is an established method of supporting neurological rehabilitation. However, particularly on the forearm, it still cannot elicit selective muscle activations that form the basis of complex hand movements. Current research approaches in the context of selective muscle activation often attempt to enable targeted stimulation by increasing the number of electrodes and combining them in electrode arrays. In order to determine the best stimulation positions and settings, manual or semi-automated algorithms are used. This approach is limited due to experimental limitations. The supportive use of simulation studies is well-established, but existing simulation models are not suitable for analyses of selective muscle activation due to missing or arbitrarily arranged innervation zones.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>This study introduces a new modeling method to design a person-specific digital twin that enables the prediction of muscle activations during FES on the forearm. The designed individual model consists of three parts: an anatomically based 3D volume conductor, a muscle-specific nerve fiber arrangement in various regions of interest (ROIs), and a standard nerve model. All processes were embedded in scripts or macros to enable automated changes to the model and the simulation setup.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The experimental evaluation of simulated strength\u2013duration diagrams showed good coincidence. The relative differences of the simulated amplitudes to the mean amplitude of the four experiments were in the same range as the inter-experimental differences, with mean values between 0.005 and 0.045. Based on these results, muscle-specific activation thresholds were determined and integrated into the simulation process. With this modification, simulated force-intensity curves showed good agreement with additionally measured curves.<\/jats:p><\/jats:sec><jats:sec><jats:title>Discussion<\/jats:title><jats:p>The results show that the model is suitable for simulating realistic muscle-specific activations. Since complex hand movements are physiologically composed of individual, selective muscle activations, it can be assumed that the model is also suitable for simulating these movements. Therefore, this study presents a new and very promising approach for developing new applications and products in the context of the rehabilitation of sensorimotor disorders.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fbioe.2024.1384617","type":"journal-article","created":{"date-parts":[[2024,6,27]],"date-time":"2024-06-27T04:53:43Z","timestamp":1719464023000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":6,"title":["Simulation of FES on the forearm with muscle-specific activation resolution"],"prefix":"10.3389","volume":"12","author":[{"given":"Johanna","family":"Baier","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sascha","family":"Selkmann","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Beate","family":"Bender","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2024,6,27]]},"reference":[{"key":"B1","volume-title":"Neuromuscular electrical stimulation: a practical guide","author":"Baker","year":"1993"},{"key":"B2","doi-asserted-by":"publisher","first-page":"e0190936","DOI":"10.1371\/journal.pone.0190936","article-title":"Electrode placement on the forearm for selective stimulation of finger extension\/flexion","volume":"13","author":"Bao","year":"2018","journal-title":"PloS one"},{"key":"B3","doi-asserted-by":"publisher","first-page":"1041","DOI":"10.1002\/(sici)1097-4598(199708)20:8<1041::aid-mus18>3.3.co;2-l","article-title":"Flexor digitorum superficialis: locations of individual muscle bellies for botulinum toxin injections","volume":"20","author":"Bickerton","year":"1997","journal-title":"Muscle & nerve"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1016\/0006-8993(66)90056-4","article-title":"Evoked action potentials and conduction velocity in human sensory nerves","volume":"3","author":"Buchthal","year":"1966","journal-title":"Brain Res."},{"key":"B5","doi-asserted-by":"publisher","first-page":"967","DOI":"10.1016\/j.medengphy.2011.03.008","article-title":"The use of hydrogel as an electrode-skin interface for electrode array fes applications","volume":"33","author":"Cooper","year":"2011","journal-title":"Med. Eng. Phys."},{"key":"B6","doi-asserted-by":"publisher","first-page":"428","DOI":"10.1109\/TNSRE.2017.2703151","article-title":"A wearable multi-site system for nmes-based hand function restoration","volume":"26","author":"Crema","year":"2018","journal-title":"IEEE Trans. neural Syst. rehabilitation Eng. a Publ. IEEE Eng. Med. Biol. Soc."},{"key":"B7","doi-asserted-by":"publisher","first-page":"468","DOI":"10.1016\/j.medengphy.2010.03.004","article-title":"Effect of subcutaneous fat thickness and surface electrode configuration during neuromuscular electrical stimulation","volume":"32","author":"Doheny","year":"2010","journal-title":"Med. Eng. Phys."},{"key":"B8","volume-title":"Influence of semg electrode positioning during muscular activity tests","author":"Duarte","year":"2016"},{"key":"B9","doi-asserted-by":"publisher","first-page":"302","DOI":"10.1113\/jphysiol.1964.sp007378","article-title":"The action potential in the myelinated nerve fibre of xenopus laevis as computed on the basis of voltage clamp data","volume":"171","author":"Frankenhaeser","year":"1964","journal-title":"J. physiology"},{"key":"B10","doi-asserted-by":"publisher","first-page":"1329","DOI":"10.1108\/COMPEL-04-2013-0118","article-title":"A two-step model to optimise transcutaneous electrical stimulation of the human upper arm","volume":"33","author":"Goffredo","year":"2014","journal-title":"COMPEL - Int. J. Comput. Math. Electr. Electron. Eng."},{"key":"B11","article-title":"Influence of subcutaneous fat thickness upon the activation volume in transcutaneous electrical stimulation to a thigh simulation model","author":"Gomez-Tames","year":"2011"},{"key":"B12","first-page":"51","article-title":"Influence of fat thickness and femur location on nerve activity computation during electrical stimulation","author":"Gomez-Tames","year":""},{"key":"B13","doi-asserted-by":"publisher","first-page":"72","DOI":"10.1166\/jmihi.2013.1139","article-title":"A simulation study on the dominance of the tissues\u2019 conductivity in the muscle recruitment","volume":"3","author":"Gomez-Tames","year":"","journal-title":"J. Med. Imaging Health Inf."},{"key":"B14","first-page":"449","article-title":"Simulation of the muscle recruitment by transcutaneous electrical stimulation in a simplified semitendinosus muscle model","volume-title":"Converging clinical and engineering research on neurorehabilitation vol. 1 of biosystems & biorobotics","author":"Gomez-Tames","year":""},{"key":"B15","first-page":"3576","article-title":"A simulation study: effect of the inter-electrode distance, electrode size and shape in transcutaneous electrical stimulation","author":"Gomez-Tames","year":"2012"},{"key":"B16","first-page":"12","article-title":"Guyton and Hall textbook of medical physiology: student consult","volume-title":"Activate at studentconsult.com. Searchable full text online","author":"Hall","year":"2011"},{"key":"B17","doi-asserted-by":"publisher","first-page":"617","DOI":"10.1007\/s00276-007-0260-y","article-title":"Location of nerve entry points of flexor digitorum profundus","volume":"29","author":"Hwang","year":"2007","journal-title":"Surg. radiologic Anat. SRA"},{"key":"B18","first-page":"273","article-title":"Workshop on transcutaneous functional electrical stimulation","volume-title":"Emerging therapies in neurorehabilitation II vol. 10 of biosystems & biorobotics","author":"Imatz-Ojanguren","year":"2016"},{"key":"B19","doi-asserted-by":"publisher","first-page":"897","DOI":"10.1093\/brain\/108.4.897","article-title":"Qualitative and quantitative morphology of human sural nerve at different ages","volume":"108","author":"Jacobs","year":"1985","journal-title":"Brain a J. neurology"},{"key":"B20","doi-asserted-by":"publisher","first-page":"35","DOI":"10.2298\/JAC0802035K","article-title":"Electrodes for transcutaneous (surface) electrical stimulation","volume":"18","author":"Keller","year":"2008","journal-title":"J. Automatic Control"},{"key":"B21","article-title":"Selective finger and wrist activation using multi-channel transcutaneous electrical stimulation electrodes","author":"Keller","year":"2007"},{"key":"B22","doi-asserted-by":"publisher","first-page":"56","DOI":"10.1186\/s12984-016-0165-2","article-title":"Advances in selective activation of muscles for non-invasive motor neuroprostheses","volume":"13","author":"Koutsou","year":"2016","journal-title":"J. neuroengineering rehabilitation"},{"key":"B23","volume-title":"Modeling transcutaneous electrical stimulation","author":"Kuhn","year":"2008"},{"key":"B24","article-title":"A 3d transient model for transcutaneous functional electrical stimulation","author":"Kuhn","year":"2005"},{"key":"B25","article-title":"A selectivity measure for transcutaneous electrodes","author":"Kuhn","year":"2007"},{"key":"B26","doi-asserted-by":"publisher","first-page":"279","DOI":"10.1007\/s11517-008-0422-z","article-title":"A model for transcutaneous current stimulation: simulations and experiments","volume":"47","author":"Kuhn","year":"","journal-title":"Med. Biol. Eng. Comput."},{"key":"B27","doi-asserted-by":"publisher","first-page":"255","DOI":"10.1109\/TNSRE.2009.2039807","article-title":"The influence of electrode size on selectivity and comfort in transcutaneous electrical stimulation of the forearm","volume":"18","author":"Kuhn","year":"2010","journal-title":"IEEE Trans. neural Syst. rehabilitation Eng. a Publ. IEEE Eng. Med. Biol. Soc."},{"key":"B28","doi-asserted-by":"publisher","first-page":"945","DOI":"10.1016\/j.medengphy.2009.05.006","article-title":"Array electrode design for transcutaneous electrical stimulation: a simulation study","volume":"31","author":"Kuhn","year":"","journal-title":"Med. Eng. Phys."},{"key":"B29","doi-asserted-by":"publisher","first-page":"456","DOI":"10.1002\/(sici)1097-0185(199707)248:3<456::aid-ar19>3.3.co;2-a","article-title":"Distribution of primary motor nerve branches and terminal nerve entry points to the forearm muscles","volume":"248","author":"Liu","year":"1997","journal-title":"Anatomical Rec."},{"key":"B30","volume-title":"Novel methods in electrical stimulation with surface electrodes","author":"Loitz","year":"2019"},{"key":"B31","doi-asserted-by":"publisher","first-page":"458","DOI":"10.1515\/cdbme-2015-0110","article-title":"Impact of electrode geometry on force generation during functional electrical stimulation","volume":"1","author":"Loitz","year":"2015","journal-title":"Curr. Dir. Biomed. Eng."},{"key":"B32","doi-asserted-by":"publisher","first-page":"66","DOI":"10.1186\/1743-0003-9-66","article-title":"A multi-pad electrode based functional electrical stimulation system for restoration of grasp","volume":"9","author":"Malesevic","year":"2012","journal-title":"J. neuroengineering rehabilitation"},{"key":"B33","doi-asserted-by":"publisher","first-page":"391","DOI":"10.1016\/S1050-6411(98)00020-0","article-title":"1998 isek congress keynote lecture: motor units: how many, how large, what kind? international society of electrophysiology and kinesiology","volume":"8","author":"McComas","year":"1998","journal-title":"J. Electromyogr. Kinesiol."},{"key":"B34","doi-asserted-by":"publisher","first-page":"29","DOI":"10.1007\/s004220050455","article-title":"Sensitivity analysis of a model of mammalian neural membrane","volume":"79","author":"McIntyre","year":"1998","journal-title":"Biol. Cybern."},{"key":"B35","doi-asserted-by":"publisher","first-page":"995","DOI":"10.1152\/jn.00353.2001","article-title":"Modeling the excitability of mammalian nerve fibers: influence of afterpotentials on the recovery cycle","volume":"87","author":"McIntyre","year":"2002","journal-title":"J. neurophysiology"},{"key":"B36","doi-asserted-by":"publisher","first-page":"329","DOI":"10.1109\/TBME.1976.324593","article-title":"Analysis of a model for excitation of myelinated nerve","volume":"23","author":"McNeal","year":"1976","journal-title":"IEEE Trans. Biomed. Eng. BME"},{"key":"B37","first-page":"293","article-title":"Electrically evoked myoelectric signals","volume":"19","author":"Merletti","year":"1992","journal-title":"Crit. Rev. Biomed. Eng."},{"key":"B38","doi-asserted-by":"publisher","first-page":"116","DOI":"10.3139\/104.112327","article-title":"Digitale Zwillinge in Interaktion mit Menschmodellen","volume":"115","author":"Neumann","year":"2020","journal-title":"Z. f\u00fcr Wirtsch. Fabr."},{"key":"B39","doi-asserted-by":"publisher","first-page":"464","DOI":"10.1136\/jnnp.31.5.464","article-title":"The fibre size and content of the radial and sural nerves","volume":"31","author":"O\u2019Sullivan","year":"1968","journal-title":"J. neurology, Neurosurg. psychiatry"},{"key":"B40","doi-asserted-by":"publisher","first-page":"657","DOI":"10.1007\/BF02476917","article-title":"Considerations of quasi-stationarity in electrophysiological systems","volume":"29","author":"Plonsey","year":"1967","journal-title":"Bull. Math. biophysics"},{"key":"B41","doi-asserted-by":"publisher","first-page":"85","DOI":"10.1002\/cne.21375","article-title":"Morphometric analysis of the fiber populations of the rat sciatic nerve, its spinal roots, and its major branches","volume":"503","author":"Prodanov","year":"2007","journal-title":"J. Comp. neurology"},{"key":"B42","doi-asserted-by":"publisher","first-page":"974","DOI":"10.1109\/TBME.1986.325670","article-title":"Analysis of models for external stimulation of axons","volume":"33","author":"Rattay","year":"1986","journal-title":"IEEE Trans. bio-medical Eng."},{"key":"B43","doi-asserted-by":"crossref","DOI":"10.1007\/978-3-7091-3271-5","volume-title":"Electrical nerve stimulation","author":"Rattay","year":"1990"},{"key":"B44","doi-asserted-by":"publisher","first-page":"335","DOI":"10.1016\/S0306-4522(98)00330-3","article-title":"The basic mechanism for the electrical stimulation of the nervous system","volume":"89","author":"Rattay","year":"1999","journal-title":"Neuroscience"},{"key":"B45","doi-asserted-by":"publisher","first-page":"50","DOI":"10.1109\/TBME.2019.2907926","article-title":"Characterizing the motor points of forearm muscles for dexterous neuroprostheses","volume":"67","author":"RaviChandran","year":"","journal-title":"IEEE Trans. bio-medical Eng."},{"key":"B46","doi-asserted-by":"publisher","first-page":"1651","DOI":"10.1109\/TNSRE.2020.2994900","article-title":"Design of transcutaneous stimulation electrodes for wearable neuroprostheses","volume":"28","author":"RaviChandran","year":"","journal-title":"IEEE Trans. neural Syst. rehabilitation Eng. a Publ. IEEE Eng. Med. Biol. Soc."},{"key":"B47","doi-asserted-by":"publisher","first-page":"235","DOI":"10.1002\/(SICI)1520-6777(1996)15:3<235::AID-NAU8>3.0.CO;2-G","article-title":"Morphometric data of canine sacral nerve roots with reference to electrical sacral root stimulation","volume":"15","author":"Rijkhoff","year":"1996","journal-title":"Neurourol. Urodynamics"},{"key":"B48","doi-asserted-by":"crossref","DOI":"10.4081\/ejtm.2016.6029","article-title":"A new semi-automatic approach to find suitable virtual electrodes in arrays using an interpolation strategy","volume-title":"In ifess 2016 Hybrid approaches of FES, ed. IFESS","author":"Salchow","year":""},{"key":"B49","doi-asserted-by":"publisher","first-page":"6029","DOI":"10.4081\/ejtm.2016.6029","article-title":"A new semi-automatic approach to find suitable virtual electrodes in arrays using an interpolation strategy","volume":"26","author":"Salchow","year":"","journal-title":"Eur. J. Transl. Myology"},{"key":"B50","doi-asserted-by":"publisher","first-page":"94","DOI":"10.1109\/TNSRE.2011.2178749","article-title":"Selectivity and resolution of surface electrical stimulation for grasp and release","volume":"20","author":"Westerveld","year":"2012","journal-title":"IEEE Trans. neural Syst. rehabilitation Eng. a Publ. IEEE Eng. Med. Biol. Soc."}],"container-title":["Frontiers in Bioengineering and Biotechnology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fbioe.2024.1384617\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,6,27]],"date-time":"2024-06-27T04:53:52Z","timestamp":1719464032000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fbioe.2024.1384617\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,6,27]]},"references-count":50,"alternative-id":["10.3389\/fbioe.2024.1384617"],"URL":"https:\/\/doi.org\/10.3389\/fbioe.2024.1384617","relation":{},"ISSN":["2296-4185"],"issn-type":[{"value":"2296-4185","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,6,27]]},"article-number":"1384617"}}