Abstract
Study Objective:
To test the hypothesis that the reflex and corticobulbar motor excitability of jaw muscles is reduced during sleep.
Design:
Polysomnographic recordings in the electrophysiological study.
Setting:
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.
Conclusions:
The results suggest that the excitability of reflex and corticobulbar-evoked activity in the jaw motor system is depressed during QS.
To test the hypothesis that the reflex and corticobulbar motor excitability of jaw muscles is reduced during sleep.
Design:
Polysomnographic recordings in the electrophysiological study.
Setting:
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.
Conclusions:
The results suggest that the excitability of reflex and corticobulbar-evoked activity in the jaw motor system is depressed during QS.
| Original language | English |
|---|---|
| Journal | Sleep |
| Volume | 36 |
| Issue number | 2 |
| Pages (from-to) | 269-280 |
| ISSN | 0161-8105 |
| DOIs | |
| Publication status | Published - 2013 |