In the rat, a species widely used to study the neural mechanisms of sleep and motor control, lingual electromyographic activity (EMG) is minimal during non-rapid eye movement (non-REM) sleep and then phasic twitches gradually increase after the onset of REM sleep. To better characterize the central neural processes underlying this pattern, we quantified EMG of muscles innervated by distinct subpopulations of hypoglossal motoneurons and nuchal (N) EMG during transitions from non-REM sleep to REM sleep. In 8 chronically instrumented rats, we recorded cortical EEG, EMG at sites near the base of the tongue where genioglossal and intrinsic muscle fibers predominate (GG-I), EMG of the geniohyoid (GH) muscle, and N EMG. Sleep-wake states were identified and EMGs quantified relative to their mean levels in wakefulness in successive 10 s epochs. During non-REM sleep, the average EMG levels differed among the three muscles, with the order being N>GH>GG-I. During REM sleep, due to different magnitudes of phasic twitches, the order was reversed to GG-I>GH>N. GG-I and GH exhibited a gradual increase of twitching that peaked at 70-120 s after the onset of REM sleep and then declined if the REM sleep episode lasted longer. We propose that a common phasic excitatory generator impinges on motoneuron pools that innervate different muscles, but twitching magnitudes are different due to different levels of tonic motoneuronal hyperpolarization. We also propose that REM sleep episodes of average durations are terminated by intense activity of the central generator of phasic events, whereas long REM sleep episodes end as a result of a gradual waning of the tonic disfacilitatory and inhibitory processes.

中文翻译：

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非快速眼动睡眠期间由舌下和上脊髓运动神经元亚群支配的肌肉的 EMG 活动之间的定量差异 - REM 睡眠转换：睡眠大脑中神经过程的一个窗口。

大鼠是一种广泛用于研究睡眠和运动控制神经机制的物种，在非快速眼动 (non-REM) 睡眠期间，舌肌电活动 (EMG) 最小，然后在 REM 发作后阶段性抽搐逐渐增加睡觉。为了更好地表征这种模式背后的中枢神经过程，我们量化了在从非快速眼动睡眠过渡到快速眼动睡眠期间由不同的舌下运动神经元和颈部 (N) EMG 亚群支配的肌肉的 EMG。在 8 只长期使用仪器的大鼠中，我们记录了皮层脑电图、舌根附近以颏舌肌和内在肌纤维为主 (GG-I) 的部位的肌电图、颏舌骨 (GH) 肌的肌电图和 N 肌电图。睡眠-觉醒状态被确定，并且肌电图相对于它们在连续 10 s 时期清醒时的平均水平进行量化。在非快速眼动睡眠期间，三块肌肉的平均 EMG 水平不同，顺序为 N>GH>GG-I。在 REM 睡眠期间，由于不同程度的阶段性抽搐，顺序颠倒为 GG-I>GH>N。GG-I 和 GH 的抽搐逐渐增加，在 REM 睡眠开始后 70-120 秒达到峰值，如果 REM 睡眠持续时间更长，则下降。我们提出，一种常见的相位兴奋性发生器会撞击支配不同肌肉的运动神经元池，但由于不同程度的强直运动神经元超极化，抽搐幅度不同。我们还提出，平均持续时间的 REM 睡眠发作被阶段性事件的中央发生器的强烈活动终止，