Yuza J
Department of Otorhinolaryngology and Physiology, School of Medicine, Chiba University.
Nihon Jibiinkoka Gakkai Kaiho. 1993 Jun;96(6):891-902. doi: 10.3950/jibiinkoka.96.891.
Laryngeal motoneurons (LMNs) innervating the intrinsic laryngeal muscles also control glottal movements such as swallowing, respiration and phonation. The present study was performed on decerebrate cats to clarify the laryngeal control mechanisms during respiration and phonation using extracellular single unit recordings from the nucleus ambiguus. First, functional differences among LMNs during the respiratory phases were investigated by analysis of the activity of LMNs innervating laryngeal adductor (TA-LCA: thyroarytenoid-lateral cricoarytenoid) or abductor (PCA: posterior cricoarytenoid) muscles; Second, laryngeal control mechanisms during phonation were investigated by the analysis of neural activity of TA-LCA motoneurons during vocal fold vibration elicited by a constant air flow through the glottis. In both cases, motoneuronal excitability changes were expressed by measuring fluctuation of peak latencies of action potentials antidromically elicited by selective stimulation of the recurrent nerve or its peripheral branch. In 14 out of 24 TA-LCA motoneurons, neuronal excitability was increased during the expiratory phase, whereas in the remaining 10, it was increased during the later half of the inspiratory and the early half of the expiratory phase. On the other hand, 9 out of 13 PCA motoneurons showed increased neuronal excitability during the end of the expiratory and the beginning of the inspiratory phase, while the remaining 4 showed increased excitability during the inspiratory phase. These results suggest that there are functional differences among the homogeneous laryngeal motoneurons. In seven TA-LCA motoneurons, neuronal excitability was decreased by vocal fold vibration elicited by phonation throughout the whole respiratory cycle. On the other hand, when the bilateral superior laryngeal nerves were cut, neuronal excitability was increased during phonation throughout the whole respiratory cycle. These results indicate that TA-LCA motoneurons receive inhibitory inputs from the superior laryngeal nerve and excitatory inputs from the recurrent laryngeal nerve during the vocal fold vibration elicited by phonation.
支配喉内肌的喉运动神经元（LMNs）也控制诸如吞咽、呼吸和发声等声门运动。本研究在去大脑猫身上进行，通过对疑核进行细胞外单单位记录来阐明呼吸和发声过程中的喉控制机制。首先，通过分析支配喉内收肌（TA-LCA：甲杓肌-环杓侧肌）或外展肌（PCA：环杓后肌）的LMNs的活动，研究呼吸各阶段LMNs之间的功能差异；其次，通过分析在恒定气流通过声门引起声带振动期间TA-LCA运动神经元的神经活动，研究发声过程中的喉控制机制。在这两种情况下，运动神经元兴奋性的变化通过测量选择性刺激喉返神经或其外周分支逆向诱发动作电位的峰值潜伏期波动来表示。在24个TA-LCA运动神经元中的14个中，神经元兴奋性在呼气期增加，而在其余10个中，在吸气后半期和呼气前半期增加。另一方面，13个PCA运动神经元中的9个在呼气末期和吸气初期显示神经元兴奋性增加，而其余4个在吸气期显示兴奋性增加。这些结果表明，同类喉运动神经元之间存在功能差异。在7个TA-LCA运动神经元中，发声引起的声带振动在整个呼吸周期中都降低了神经元兴奋性。另一方面，切断双侧喉上神经后，发声期间整个呼吸周期的神经元兴奋性都增加。这些结果表明，在发声引起的声带振动期间，TA-LCA运动神经元接受来自喉上神经的抑制性输入和来自喉返神经的兴奋性输入。
