A Neuroanatomical and Electrophysiological Analysis of the Motor Units of the Major Flight Muscles in the Pigeon (Columba livia) and Starling (Sturnus vulgaris)

拟议的鸟类主要飞行肌肉的神经解剖学和电生理学研究旨在提供与以下方面相关的数据：1)四足动物之间神经肌肉设计的进化；2)运动运动神经元和肌肉单位(收缩速度，力量产生，疲劳性)从翅膀的主要降压肌(胸肌)和升肌(胸骨上肌)功能性分离的运动单位的特性。糖原耗竭技术将能够描述每种单位类型的神经支配比率和外周分布模式，并首次提供鸟类飞行肌肉中肌肉纤维的组织化学-生理学关联。这些肌肉在脊髓内的运动核团的分布和一般形态将通过解剖学示踪剂(辣根过氧化物酶)来确定。预期结果的意义如下：首先，Goslow的假设是，在四足动物之间不同的运动系统的进化过程中，四足动物肩部运动功能的神经控制机制保持相对保守，将通过检查神经肌肉组织来评估。其次，在鸽子飞行时的胸肌内，两种肌肉纤维物种之间的募集似乎符合“大小原则”。然而，肌肉纤维力学和效率理论表明，有氧纤维在种群中的招募顺序(鸽子中80%，八哥中100%)可能没有顺序。这项拟议的研究首次详细说明了飞行肌肉运动单位的结构和功能组织，这将使这些假说得以评估。

The proposed neuroanatomical and electrophysiological study of the major flight muscles of birds is designed to provide data relevant to 1) the evolution of neuromuscular design among tetrapods, and 2) the recruitment of motor motoneuron and muscle unit (contraction speed, force production, fatigability) properties of functionally isolated motor units from the major depressor (pectoralis) and elevator (supracoracoideus) muscles of the wing. Glycogen depletion techniques will permit description of innervation ratio and peripheral distribution patterns of each unit type, as well as provide the first histochemical- physiological correlation for muscle fibers in avian flight muscles. The distribution and general morphology of the motor nuclei within the spinal cord for each of these muscles will be established with an anatomical tracer (horseradish peroxidase). The significance of expected results is as follows: First, Goslow's hypothesis that throughout the evolution of diverse locomotor systems among tetrapods, the neural control mechanism for tetrapod shoulder function during locomotion has remained relatively conservative will be evaluated by examining the neuromuscular organization. Second, within the pectoralis of pigeons during flight, recruitment between two muscle fiber species appears to be consistent with the "size principle." However, theory of muscle fiber mechanics and efficiency suggests that the recruitment order in populations of aerobic fibers (80% in pigeons, 100% in starlings) may not be ordered. The proposed study offers the first detailed account of the structural and functional organization of flight muscle motor units which will allow evaluation of these hypotheses.