Songbirds produce complex vocalizations by coordinating neuromuscular control of syrinx, respiratory system and upper vocal tract. The functional roles of syringeal muscles have been documented mainly with correlative data, which have suggested that synergistic activation plays a role in the fine control of vocal features. However, the specific involvement of individual muscles in achieving this fine control is still largely unknown. Here we investigate the contributions of the two main airflow controlling muscles, the dorsal and ventral tracheobronchial muscles in the zebra finch, through a new approach. Ablation of the muscle insertion on the cartilage framework reveals detailed insights into their respective roles in the fine control of song features. Unilateral ablation of a tracheobronchial muscle resulted in mostly subtle changes of the air sac pressure pattern and song features. Effects of ablation varied with the acoustic elements, thus indicating a context-dependent specific synergistic activation of muscles. High frequency notes were most affected by the ablation, highlighting the importance of coordinated bilateral control. More pronounced effects on song features and air sac pressure were observed after bilateral ablation of the dorsal tracheobronchial muscles. The results illustrate that the gating muscles serve multiple functions in control of acoustic features, and that each feature arises through context-dependent, synergistic activation patterns of syringeal muscles. Although many changes after the ablation are subtle, they fall within the perceptual range and thus may control behaviorally relevant features of sound. These data therefore provide important specific details about the underlying motor code for song production.

中文翻译：

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鸣禽鸣管中声音输出的多功能双侧肌肉控制

鸣禽通过协调对空洞、呼吸系统和上声道的神经肌肉控制来产生复杂的发声。注射器肌肉的功能作用主要用相关数据记录，这表明协同激活在声音特征的精细控制中起作用。然而，个体肌肉在实现这种精细控制方面的具体参与在很大程度上仍是未知的。在这里，我们通过一种新方法研究了斑胸草雀背侧和腹侧气管支气管肌肉这两个主要的气流控制肌肉的贡献。软骨框架上肌肉插入的消融揭示了对它们在精细控制歌曲特征中各自作用的详细见解。气管支气管肌肉的单侧消融导致气囊压力模式和歌曲特征的大部分细微变化。消融的效果随声学元素而变化，因此表明肌肉的上下文相关特定协同激活。高频音符受消融影响最大，突出了协调双边控制的重要性。在双侧气管支气管背肌消融后观察到对歌曲特征和气囊压力的更显着影响。结果表明，门控肌肉在控制声学特征方面具有多种功能，并且每个特征都是通过注射器肌肉的上下文相关、协同激活模式产生的。虽然消融后的许多变化是微妙的，它们属于感知范围，因此可以控制声音的行为相关特征。因此，这些数据提供了有关歌曲制作的基础运动代码的重要具体细节。