Neuromechanical Control of Elastic Energy Storage and Recovery during Ballistic Movements

在过去的20年里，越来越清楚的是，了解生物力学对于理解运动控制是必要的。然而，我们对生物力学如何影响运动控制的确切了解仍处于初级阶段。对这个问题的深入理解的一个障碍是动物身体的绝对复杂性。肌肉的数量远远超过关节的数量，除了作为收缩和产生力量的传统角色外，肌肉可能还具有各种不同的功能。本研究以蟾蜍舌头弹道投射为模型系统，探讨生物力学与神经运动控制之间的关系。蟾蜍的弹道舌头投射是已知最快的运动之一，但它与典型的脊椎动物运动系统有许多共同的特征。由于相对较好的理解，蟾蜍的弹道舌头投影是研究生物力学和神经控制之间关系的一个容易处理的模型系统。这一建议的基本思想是从预测生物力学模型向后工作，以理解产生运动的神经回路的设计。这项研究的第一个目标是建立一个完整的、可预测的生物力学模型，用于研究蟾蜍舌头弹道投射过程中的弹性能量存储和恢复。为了完成生物力学建模，研究人员将确定：(1)允许弹性能量存储的力(S)，包括对抗肌肉的共同激活以及被动机制；以及(2)允许恢复弹性应变能量的机械和神经事件。拟议研究的第二个目标是利用目前对生物力学的理解来开发和测试关于控制弹道舌头投射的神经回路设计的假设。利用神经解剖学技术，将描述本体感觉神经元、运动神经元、小脑和内侧网状结构的运动前神经元之间的神经联系，这些神经元接受感觉输入并控制运动神经元的活动。这些研究将为神经力学领域的三个重要问题提供洞察力：(1)拮抗性肌肉收缩对运动控制的贡献；(2)从感觉输入到运动输出的前馈运动控制神经回路的结构；(3)肌肉协同的神经解剖学基础。这一提议的更广泛影响包括一个多学科团队的合作，该团队由一名生物机械师、一名行为神经学家和一名神经解剖学家组成。此外，在国家普通医学科学研究所(NIH)的支持下，拟议的研究将为代表性不足的学生提供参与机会，特别是拉美裔和美洲原住民。

Over the past 20 years, it has become increasingly clear that an understanding of biomechanics is necessary for understanding motor control. However, our knowledge of precisely how biomechanics influences the control of movement is still rudimentary. One obstacle to developing a deeper understanding of this problem is the sheer complexity of animal bodies. The number of muscles far exceeds the number of joints, and muscles may serve a variety of different functions in addition to their conventional roles as contractile and force-producing elements. The research proposed here uses ballistic tongue projection in toads as a model system to investigate the relationship between the biomechanics and neural control of movement. Ballistic tongue projection in toads is one of the fastest known movements, yet it shares many general features with typical vertebrate motor systems. Because it is relatively well understood, ballistic tongue projection in toads is a tractable model system for investigating the relationship between biomechanics and neural control. The fundamental idea of this proposal is to work backward from a predictive biomechanical model, toward an understanding of the design of the neural circuits that produce movement. The first goal of the proposed research is to develop a complete and predictive biomechanical model of elastic energy storage and recovery during ballistic tongue projection in toads. To complete the biomechanical modeling, the investigators will determine: (1) the force(s) that permit elastic energy storage, including co-activation of antagonistic muscles as well as passive mechanisms; and (2) the mechanical and neural events that permit recovery of elastic strain energy. The second goal of the proposed studies is to use present understanding of biomechanics to develop and test hypotheses about the design of the neural circuits that control ballistic tongue projection. Using neuroanatomical techniques, descriptions will be developed of the neural connections among proprioceptive sensory neurons, motor neurons, and the pre-motor neurons of the cerebellum and medial reticular formation that receive sensory input and control the activity of motor neurons. The proposed studies will provide insight into three important issues in the field of neuromechanics: (1) the contribution of antagonistic muscle contraction to motor control; (2) the structure of neural circuits for feed-forward control of movement, from sensory input to motor output; and (3) the neuroanatomical basis for muscle synergies. The broader impacts of this proposal include the collaboration of a multidisciplinary team, composed of a biomechanist, a behavioral neuroscientist, and a neuroanatomist. In addition, through support from the National Institute of General Medical Sciences (NIH), the proposed studies will provide opportunities for participation of underrepresented students, especially Hispanics and Native Americans.