{
  "abstract": "Background: Immediate transcranial evoked potentials (iTEPs) are ultra-early electroencephalographic responses elicited by single-pulse transcranial magnetic stimulation (TMS) of the primary motor cortical hand area (M1-HAND). Their characteristic latency, waveform, and sensitivity to short-interval intracortical inhibition suggest a close relationship to the cortical generators of indirect corticospinal volleys (I-waves). Here, we tested the hypothesis that iTEPs constitute a fundamental physiological response of human motor cortex and therefore generalize across motor representations, including the leg representation (M1-LEG). Methods: Single-pulse TMS was delivered over the motor cortical representation of the right tibialis anterior (TA) in 16 healthy volunteers. In a subset of participants (n=10), stimulus-response curves and paired-pulse short-interval intracortical inhibition (SICI) measures were obtained. Results: TMS of M1-LEG elicited reproducible iTEPs consisting of a slow positive deflection with superimposed high-frequency peaks with topographic maxima in electrodes adjacent to the stimulation site. M1-LEG iTEPs emerged close to active motor threshold and increased in prevalence and amplitude with increasing stimulation intensity. Paired-pulse stimulation produced consistent SICI of the second and third iTEP peaks. M1-LEG stimulation also evoked conventional later TEPs with latencies and polarities closely resembling those recorded after M1-HAND stimulation. Conclusions: TMS of the human M1-LEG elicits robust iTEPs that closely resemble those recorded from M1-HAND in their timing, intensity dependence, and sensitivity to intracortical inhibition. These findings indicate that iTEPs are not specific to M1-HAND but reflect a general physiological response of human motor cortex closely linked to corticospinal I-wave generation. This broadens their utility as a non-invasive probe of excitatory and inhibitory circuit dynamics throughout the human motor system.",
  "abstract_shown": true,
  "affiliations": [
    "Danish Research Centre for Magnetic Resonance, Department of Radiology and Nuclear Medicine, Copenhagen University Hospital - Amager and Hvidovre, Kettegard All"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 6,
  "authors": [
    {
      "name": "M. M. Beck"
    },
    {
      "name": "M. Nuyts"
    },
    {
      "name": "L. Sakalauskaite"
    },
    {
      "name": "J. Rothwell"
    },
    {
      "name": "H. R. Siebner"
    },
    {
      "affs": [
        0
      ],
      "name": "L. Christiansen"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bhkkfazn8pne9.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.09.30.755678",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.09.30.755678v1.full",
  "id": "bhkkfazn8pne9",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.09.30.755678v1",
  "language": null,
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "neuroscience"
    ],
    [
      "openalex",
      "2808|Transcranial Magnetic Stimulation Studies"
    ]
  ],
  "openalex": "W7220938845",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.09.30.755678v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bhkkfazn8pne9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:26:29Z",
      "native_id": "10.64898/2026.09.30.755678",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.09.30.755678v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "biorxiv:neuroscience",
      "subfield": "neuroscience"
    }
  ],
  "title": "Immediate cortical responses to transcranial magnetic stimulation of the human motor leg area",
  "title_text": "Immediate cortical responses to transcranial magnetic stimulation of the human motor leg area",
  "type": "preprint",
  "updated_at": "2026-10-30T12:26:29Z",
  "url": "https://research.draconitic.com/paper/bhkkfazn8pne9",
  "venue": "bioRxiv",
  "versions": []
}