Neuromechanical Control of Elastic Energy Storage and Recovery during Ballistic Movements

在过去的20年里，人们越来越清楚地认识到，理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精确地影响运动控制的知识仍然是初步的。对这一问题进行深入理解的一个障碍是动物身体的复杂性。肌肉的数量远远超过关节的数量，肌肉除了作为收缩和产生力的元素的传统角色之外，还可以提供各种不同的功能。本研究以蟾蜍舌的弹道投射为模型系统，探讨生物力学与运动神经控制之间的关系。蟾蜍的弹道式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特征。因为它是比较好理解的，蟾蜍的弹道舌投射是一个易于处理的模型系统，用于研究生物力学和神经控制之间的关系。这个建议的基本思想是从预测生物力学模型向后工作，了解产生运动的神经回路的设计。本研究的第一个目标是建立一个完整的预测性生物力学模型，研究蟾蜍舌弹式投射过程中弹性能量的储存和恢复。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，包括对抗肌肉的共同激活以及被动机制;和（2）允许恢复弹性应变能的机械和神经事件。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。使用神经解剖学技术，描述将开发的本体感觉神经元，运动神经元，和小脑和内侧网状结构的前运动神经元，接受感觉输入和控制运动神经元的活动之间的神经连接。拟议的研究将深入了解神经力学领域的三个重要问题：（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控制运动的神经回路结构;（3）肌肉协同作用的神经解剖学基础。这项提议的更广泛影响包括一个多学科团队的合作，该团队由一名生物力学家，一名行为神经科学家和一名神经解剖学家组成。此外，通过国家普通医学科学研究所（NIH）的支持，拟议的研究将为代表性不足的学生，特别是西班牙裔和美洲原住民提供参与的机会。

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.