Task-dependent neural control of regions within human genioglossus

Abstract

Anatomical and imaging evidence suggests neural control of oblique and horizontal compartments of the genioglossus differs. However, neurophysiological evidence for differential control remains elusive. This study aimed to determine whether there are differences in neural drive to the oblique and horizontal regions of the genioglossus during swallowing and tongue protrusion. Adult participants (N=63; 48M) were recruited from a sleep clinic; 41 had Obstructive Sleep Apnoea (OSA: 34M, 8F). Electromyographic (EMG) was recorded at rest (awake, supine) using 4 intramuscular fine-wire electrodes inserted percutaneously into the anterior oblique, posterior oblique, anterior horizontal and posterior horizontal genioglossus. Epiglottic pressure and nasal airflow were also measured. During swallowing, two distinct EMG patterns were observed- a monophasic response (single EMG peak) and a biphasic response (two bursts of EMG). Peak EMG and timing of the peak relative to epiglottic pressure were significantly different between patterns (linear mixed models, p<0.001). Monophasic activation was more likely in the horizontal than oblique region during swallowing (OR=6.83, CI=3.46-13.53, p<0.001). In contrast, during tongue protrusion, activation patterns and EMG magnitude were not different between regions. There were no systematic differences in EMG patterns during swallowing or tongue protrusion between OSA and non-OSA groups. These findings provide evidence for functional differences in the motoneuronal output to the oblique and horizontal compartments, enabling differential task-specific drive. Given this, it is important to identify the compartment from which EMG is acquired. We propose that the EMG patterns during swallowing may be used to identify the compartment where a recording electrode is located.

Regional associations between inspiratory tongue dilatory movement and genioglossus activity during wakefulness in people with obstructive sleep apnoea

“…Insertion and recording procedures were described in Yeung et al. ( 2022 ). We used four percutaneous fine‐wire electrodes (Teflon‐coated stainless‐steel diameter 0.08 mm, #791500 A‐M Systems Inc., Sequim, WA, USA) to target the same four tongue neuromuscular compartments defined for the imaging analysis (Fig.…”

“…EMG was recorded in awake supine participants during nasal breathing using a monopolar electrode configuration with the reference electrode placed on the forehead. Insertion and recording procedures were described in Yeung et al (2022). We used four percutaneous fine-wire electrodes (Teflon-coated stainless-steel diameter 0.08 mm, #791500 A-M Systems Inc., Sequim, WA, USA) to target the same four tongue neuromuscular compartments defined for the imaging analysis (Fig.…”

The influence of alcohol on genioglossus single motor units in men and women during wakefulness

“…Wires were inserted between 10 and 20 mm from the posteroinferior margin of the mandible, at a depth of 2–2.5 cm from the surface and ∼5 mm on each side of the midline. The variation in wire placements was performed to maximize chances of identifying unique MUs and to ensure that sufficient EP and ET units were recorded as these are typically found more superficially in the horizontal region of the genioglossus (Luu et al., 2018 ; Yeung et al., 2022 ). GG EMG signals were amplified and band‐pass filtered from 30 to 10 kHz (model P511, Grass TeleFactor; Grass Technologies, West Warwick, RI, USA).…”

Recent Progress in Long-Term Sleep Monitoring Technology

“…In 2018, Beniczky et al used wearable EMG signals to capture the evolution of TCS-related signals on the human surface for the detection of muscle rigidity and epilepsy occurring during sleep [ 66 ]. In 2022, Yeung et al completed the diagnosis of obstructive sleep through muscle electrical signals in the tongue and epiglottis to epiglottal pressure and nasal airflow and then through EMG at the level of muscle movement [ 107 ]. The diagnosis of apnea was made by Rebelo after collecting the EMG signals generated by the apical muscles of the tongue and generating electrical signals to stimulate the apical muscles of the tongue to terminate the respiratory obstruction when sleep apnea was detected [ 108 ].…”