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Non-invasive Imaging of Single Human Motor Units

Lookup NU author(s): Matt Birkbeck, Dr Linda HeskampORCiD, Dr Ian Schofield, Professor Andrew BlamireORCiD, Professor Roger Whittaker



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract: Objective: To determine the size, shape and distribution of single human motor units in-vivo in healthy controls of different ages. Methods: A novel diffusion-weighted magnetic resonance imaging (MRI) technique was used in combination with in-scanner electrical stimulation to quantify the shape, cross-sectional area, and dimensions of individual motor units in 10 healthy subjects. Results: Thirty-one discrete motor units were studied. The majority were elliptical or crescent shaped, but occasional split motor units were observed. The mean motor unit cross sectional area was 26.7 ± 11.2 mm2, the mean maximum dimension was 10.7 ± 3.3 mm, and the mean minimum dimension was 4.5 ± 1.2 mm. Subjects aged over 40 had significantly larger maximum dimensions than those below this age (p < 0.05). Conclusions: Motor unit MRI (MUMRI) is a novel technique capable of revealing the size, shape and position of multiple motor units in human muscles. It is reproducible, non-invasive, and sufficiently sensitive to detect physiologically relevant changes in motor unit morphology with age. Significance: To our knowledge, these results provide the first imaging assessment of human motor unit morphology. The technique shows promise both as a diagnostic tool and as a biomarker in longitudinal studies of disease progression.

Publication metadata

Author(s): Birkbeck MG, Heskamp L, Schofield IS, Blamire AM, Whittaker RG

Publication type: Article

Publication status: Published

Journal: Clinical Neurophysiology

Year: 2020

Volume: 131

Issue: 6

Pages: 1399-1406

Print publication date: 01/06/2020

Online publication date: 21/02/2020

Acceptance date: 11/02/2020

Date deposited: 12/02/2020

ISSN (print): 1388-2457

ISSN (electronic): 1872-8952

Publisher: Elsevier Ireland Ltd.


DOI: 10.1016/j.clinph.2020.02.004


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Funder referenceFunder name
NIHR Newcastle Biomedical Resaerch Centre