Motor unit territories in human genioglossus estimated with multichannel intramuscular electrodes
Journal article, 2018

The discharge patterns of genioglossus motor units during breathing have been well-characterized in previous studies, but their localization and territories are not known. In this study, we used two newly developed intramuscular multichannel electrodes to estimate the territories of genioglossus motor units in the anterior and posterior regions of the muscle. Seven healthy men participated. Each electrode contained fifteen bipolar channels, separated by 1 mm, and was inserted percutaneously below the chin, perpendicular to the skin, to a depth of 36 mm. Single motor unit activity was recorded with subjects awake, supine, and breathing quietly through a nasal mask for 180 s. Motor unit territories were estimated from the spike-triggered averages of the electromyographic signal from each channel. A total of 30 motor units were identified: 22 expiratory tonic, 1 expiratory phasic, 2 tonic, 3 inspiratory tonic, and 2 inspiratory phasic. Motor units appeared to be clustered based on unit type, with peak activities for expiratory units predominantly located in the anterior and superficial fibers of genioglossus and inspiratory units in the posterior region. Of these motor unit types, expiratory tonic units had the largest estimated territory, a mean 11.3 mm (SD 1.9). Estimated territories of inspiratory motor units ranged from 3 to 6 mm. In accordance with the distribution of motor unit types, the estimated territory of genioglossus motor units varied along the sagittal plane, decreasing from anterior to posterior. Our findings suggest that genioglossus motor units have large territories relative to the cross-sectional size of the muscle. NEW&NOTEWORTHY In this study, we used a new multichannel intramuscular electrode to address a fundamental property of human genioglossus motor units. We describe the territory of genioglossus motor units in the anterior and posterior regions of the muscle and show a decrease in territory size from anterior to posterior and that expiratory-related motor units have larger estimated territories than inspiratory-related motor units.

Author

Billy L. Luu

Neuroscience Research Australia (NeuRA)

Silvia Muceli

University Medical Center Göttingen

Julian P. Saboisky

Neuroscience Research Australia (NeuRA)

Dario Farina

University Medical Center Göttingen

Martin E. Héroux

Neuroscience Research Australia (NeuRA)

Lynne E. Bilston

Neuroscience Research Australia (NeuRA)

Simon C. Gandevia

Neuroscience Research Australia (NeuRA)

Jane E. Butler

Neuroscience Research Australia (NeuRA)

Journal of Applied Physiology

8750-7587 (ISSN) 1522-1601 (eISSN)

Vol. 124 3 664-671

Subject Categories

Sport and Fitness Sciences

Physiology

Public Health, Global Health, Social Medicine and Epidemiology

DOI

10.1152/japplphysiol.00889.2017

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Latest update

4/1/2021 1