{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T06:04:59Z","timestamp":1782281099652,"version":"3.54.5"},"posted":{"date-parts":[[2026,2,9]]},"group-title":"Neuroscience","reference-count":51,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,2,9]],"date-time":"2026-02-09T00:00:00Z","timestamp":1770595200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/www.biorxiv.org\/about\/FAQ#license"}],"funder":[{"name":"National Institutes of Health (NIH) NINDS","award":["K01NS127936"],"award-info":[{"award-number":["K01NS127936"]}]},{"name":"National Institutes of Health (NIH) NINDS","award":["T32NS126157"],"award-info":[{"award-number":["T32NS126157"]}]},{"name":"Biomedical Engineering Department, McKelvey School of Engineering, Washington University in St. Louis"},{"DOI":"10.13039\/100023940","name":"Department of Neurosurgery, School of Medicine, Washington University in St. Louis","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100023940","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,2,9]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>Transcutaneous spinal cord stimulation (tSCS) of the cervical spinal cord has been thought to modulate lumbar networks, leading to the hypothesis that leg muscle recruitment may occur via recruitment of long-range spinal connections between cervical and lumbar circuits. To directly test this hypothesis, we compared arm and leg muscle responses elicited in unimpaired participants (N = 12) by cervical tSCS with the anodes placed over the iliac crests, with the anodes placed over the clavicles, and with lumbar tSCS as a control for leg muscle recruitment via the posterior root-muscle reflex. The idea of tSCS targeting cervico-lumbar connectivity would suggest that cervical stimulation could evoke responses in leg muscles. However, in our experiments, leg responses via cervical tSCS were only observed when the anodes were placed over the iliac crests, but not over the clavicles. These leg muscle responses had shorter latencies than those with lumbar tSCS and showed minimal post-activation depression, indicating efferent rather than afferent recruitment. Therefore, changes in leg muscle excitability by cervical-iliac tSCS previously attributed to descending cervical circuits could instead be explained by direct recruitment of efferent fibers near the iliac anodes. These findings suggest that cervical tSCS alone does not engage leg muscle motoneurons via long-range spinal or bidirectional pathways. Therefore, our study highlights the need to carefully consider electrode configuration when interpreting cervical tSCS mechanisms and additional or unexpected rehabilitative effects that extend caudally from the cervical spinal cord.<\/jats:p>","DOI":"10.64898\/2026.02.06.702847","type":"posted-content","created":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T05:10:20Z","timestamp":1770700220000},"source":"Crossref","is-referenced-by-count":0,"title":["Neural mechanisms underlying leg muscle responses during cervical transcutaneous spinal cord stimulation"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-9239-2307","authenticated-orcid":false,"given":"Natalie","family":"Phelps","sequence":"first","affiliation":[{"name":"Department of Biomedical Engineering, Washington University in St. Louis"},{"name":"Division of Neurotechnology, Washington University School of Medicine in St. Louis"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1144-3942","authenticated-orcid":false,"given":"Rodolfo","family":"Keesey","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Washington University in St. Louis"},{"name":"Division of Neurotechnology, Washington University School of Medicine in St. Louis"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-1265-2945","authenticated-orcid":false,"given":"Rachel","family":"Hawthorn","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Washington University in St. Louis"},{"name":"Division of Neurotechnology, Washington University School of Medicine in St. Louis"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-5887-3472","authenticated-orcid":false,"given":"Carolyn","family":"Atkinson","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Washington University in St. Louis"},{"name":"Division of Neurotechnology, Washington University School of Medicine in St. Louis"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0068-7124","authenticated-orcid":false,"given":"Ismael","family":"Se\u00e1\u00f1ez","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Washington University in St. Louis"},{"name":"Division of Neurotechnology, Washington University School of Medicine in St. Louis"},{"name":"Department of Neurosurgery, Washington University School of Medicine in St. Louis"},{"name":"Department of Electrical and Systems Engineering, Washington University in St. Louis"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026021209250922000_2026.02.06.702847v1.1","doi-asserted-by":"crossref","first-page":"589","DOI":"10.3390\/biomedicines11020589","article-title":"Transcutaneous Cervical Spinal Cord Stimulation Combined with Robotic Exoskeleton Rehabilitation for the Upper Limbs in Subjects with Cervical SCI: Clinical Trial","volume":"11","year":"2023","journal-title":"Biomedicines"},{"key":"2026021209250922000_2026.02.06.702847v1.2","doi-asserted-by":"crossref","unstructured":"Chandrasekaran, S. et al. 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