JAW-OPENING REFLEX AND MOTOR EXCITABILITY IN PRIMATE QUIET SLEEP
Jaw-Opening Reflex and Corticobulbar Motor Excitability Changes During Quiet Sleep in Non-Human Primates
Dongyuan Yao, MD, PhD1,2; Gilles J. Lavigne, DMD, PhD, FRCD3,4; Jye-Chang Lee, PhD2; Kazunori Adachi, DDS, PhD5; Barry J. Sessle, MDS, PhD2
1Centre for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark; 2Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada; 3Faculty of Dental Medicine, Université de Montréal, Québec, Canada; 4Sleep Research Center and Surgery Department, Hôpital du Sacré-Cœur de Montréal, Québec, Canada; 5Department of Pharmacology, Nihon University School of Dentistry, Tokyo, Japan
To test the hypothesis that the reflex and corticobulbar motor excitability of jaw muscles is reduced during sleep.
Polysomnographic recordings in the electrophysiological study.
University sleep research laboratories.
Participants and Interventions:
The reflex and corticobulbar motor excitability of jaw muscles was determined during the quiet awake state (QW) and quiet sleep (QS) in monkeys (n = 4).
Measurements and Results:
During QS sleep, compared to QW periods, both tongue stimulation-evoked jaw-opening reflex peak and root mean square amplitudes were significantly decreased with stimulations at 2-3.5 × thresholds (P < 0.001). The jaw-opening reflex latency during sleep was also significantly longer than during QW. Intracortical microstimulation (ICMS) within the cortical masticatory area induced rhythmic jaw movements at a stable threshold (≤ 60 μA) during QW; but during QS, ICMS failed to induce any rhythmic jaw movements at the maximum ICMS intensity used, although sustained jaw-opening movements were evoked at significantly increased threshold (P < 0.001) in one of the monkeys. Similarly, during QW, ICMS within face primary motor cortex induced orofacial twitches at a stable threshold (≤ 35 μA), but the ICMS thresholds were elevated during QS. Soon after the animal awoke, rhythmic jaw movements and orofacial twitches could be evoked at thresholds similar to those before QS.
The results suggest that the excitability of reflex and corticobulbar-evoked activity in the jaw motor system is depressed during QS.
Yao D; Lavigne GJ; Lee JC; Adachi K; Sessle BJ. Jaw-opening reflex and corticobulbar motor excitability changes during quiet sleep in non-human primates. SLEEP 2013;36(2):269-280.