Respiratory activities of intrinsic tongue muscles

描述(申请人提供)：舌头的运动取决于内在肌肉(舌头的起源和插入)和外在肌肉(附着在骨骼上并插入舌头)的动作。这些肌肉在吞咽、呼吸、咀嚼和说话中起着关键作用。外在肌肉的收缩通常被认为会改变舌位(突出或后缩)，而内在舌肌的收缩则会改变舌形。到目前为止，研究哺乳动物舌头功能的呼吸相关影响的研究主要集中在呼吸控制和外在舌肌的功能上。内源性舌肌与呼吸相关的控制和功能，以及它们对外源性舌肌活动的影响尚不清楚。 新近的研究结果表明，舌内肌可能参与舌突和舌后缩，并促进舌外肌在吞咽中的作用。根据这些发现，我们的目标是表征体内固有舌肌与呼吸相关的活动。本应用的具体目的是检验以下假设：(1)在潮气呼吸期间，舌内肌和外源性舌肌共同激活；(2)内源性和外源性舌肌活动受到中枢和外周化学感受器和呼吸道机械感受器的平行调节；(3)在化学感受器和机械感受器反馈的扰动下，内在和外源性舌肌的肌电表现出相似的起搏时间和爆发特征。 实验将在乌拉坦麻醉的自发呼吸的雄性Spraogue-Dawley大鼠身上进行。在下列每种情况下，将获得舌肌、肋间内肌和上纵肌的同步肌电记录：(1)缺氧、高碳酸血症和窒息，以评估中枢和外周化学感受器刺激对舌固有肌肉活动的影响；(2)喉上神经切断前后，以及舌神经切断前后，量化上呼吸道机械感觉调节对舌固有肌肉活动的影响；(3)在单呼吸气道阻断和不阻断单呼吸气道的情况下，量化肺容量变化对驱动舌固有肌肉活动的影响。这项工作的结果将加深我们对舌肌功能的理解，并为舌肌活动在呼吸和其他行为(如咀嚼和吞咽)中的调节提供广泛的见解。

DESCRIPTION (provided by applicant): Tongue movement depends on the actions of both intrinsic (origin and insertion in the tongue) and extrinsic (attached to bone and inserted into the tongue) muscles. These muscles play a key role in swallowing, breathing, chewing, and speaking. Contraction of the extrinsic muscles is generally considered to change tongue position (protrusion or retrusion), whereas contraction of the intrinsic tongue muscles changes tongue shape. To date, research that examines the respiratory-related effects of tongue function in mammals has focused exclusively on the respiratory control and function of the extrinsic tongue muscles. The respiratory-related control and function of the intrinsic tongue muscles and their bearing on extrinsic tongue muscle activity are still unknown. Recent findings indicate that the intrinsic tongue muscles may contribute to tongue protrusion and retraction, and facilitate the actions of the extrinsic tongue muscles in swallowing. In light of these findings, our objective is to characterize the respiratory-related activities of the intrinsic tongue muscles in vivo. The specific goals of the present application are to test the following hypotheses: (1) intrinsic tongue muscles are co-activated with extrinsic tongue muscles during resting tidal breathing; (2) intrinsic and extrinsic tongue muscle activities are modulated in parallel by central and peripheral chemoreceptors and airway mechanoreceptors; and (3) the EMG of intrinsic and extrinsic tongue muscles exhibit similar onset times and burst characteristics during perturbations of chemoreceptor and mechanoreceptor feedback. Experiments will be conducted on urethane anesthetized, spontaneously breathing male Sprague-Dawley rats. Simultaneous EMG recordings of the hyoglossus, internal intercostal muscles and superior longitudinal muscles will be obtained under each of the following conditions: (1) hypoxia, hypercapnia, and asphyxia, to assess the effects of central and peripheral chemoreceptor stimulation of intrinsic tongue muscle activities; (2) before and after superior laryngeal nerve section, and before and after lingual nerve section, to quantify the influence of upper airway mechanosensory modulation of intrinsic tongue muscle activities; (3) with and without single-breath airway occlusion, to quantify the influence of phasic lung volume changes on drive to intrinsic tongue musculature. The results of this work will enhance our understanding of the functions of the tongue musculature and provide broad insights into the modulation of tongue muscle activities in breathing and other behaviors such as chewing and swallowing.