Understanding adaptive mechanisms in locomotion by integrating motor control, tissue performance and mechanical constraint

动物的运动是神经指令、组织性能和环境机械约束复杂结合的结果。我们对这些因素如何结合导致动物灵活运动的理解是有限的，正如工程机器人无法在复杂环境中导航所证明的那样。我的研究项目旨在建立在我们对活动组织（神经和肌肉）的了解基础上，并将其应用于系统的被动约束（骨骼、结缔组织和外部环境的材料特性）。我们将使用与水和陆地相关的不同机械环境来测试运动过程中行为和组织性能的变化。从组织到整个动物，该研究项目使用比较生物力学，生物材料性能测试和建模来阐明驱动运动性能的机制。目的1：量化运动中的机械约束。我们将量化运动控制模式（肌电图技术）和反作用力（力板和粒子成像测速技术）在模型两栖鱼自由行走和游泳。提取的数据将指导主动（肌肉）和被动（骨骼和结缔组织）组织的材料性能测试，以测试不断变化的外力环境影响动物组织运作的安全系数的假设。被动组织的结构贡献的量化和通过新的运动范围改变肌肉性能将解决外部和内部力量如何限制生物力学性能的预测，并在长期内引起塑性组织反应。目的2：通过建模预测绩效。来自整个动物和组织实验的实验数据将为hill型和有限元模型提供信息，以绘制鳍和身体在整个步骤/游泳周期中所经历的力分布图。这些模型将通过量化导致组织可塑性的力的大小和方向来验证骨骼和肌肉形态可塑性是由环境力变化引起的假设。目标3：量化塑性对性能的影响。发育可塑性可以极大地改变动物的形态；这种变化如何影响性能还没有得到充分的研究。利用我们已建立的陆地养鱼技术，我们将通过分析陆地适应个体的行为和组织材料特性的变化，将可塑性与功能表现联系起来。驯化鱼的数据将测试个体组织/力模型（目标2），目的是产生一个总体预测模型，包括可塑性对组织性能和整体动物功能的影响。本研究项目反复使用多种方法，将主动组织行为与被动机械约束相结合，以解释动物组织的适应能力和由此产生的运动表现。

Animal locomotion is the result of a complex combination of neural commands, tissue performance and environmental mechanical constraint. Our understanding of how these combine to result in flexible animal locomotion is limited, as demonstrated by the inability of engineered robots to navigate complex environments. My research program aims to build on what we know about active tissues (nerves and muscles) and apply it in the context of the system's passive constraints (material properties of bones, connective tissue and the external environment). We will use the different mechanical environments associated with water and land to test changes in behaviour and tissue performance during locomotion. From tissues to the whole-animal, this research program uses comparative biomechanics, bio-material properties testing and modeling to clarify the mechanisms that drive locomotory performance. Objective 1: Quantify mechanical constraint in locomotion. We will quantify motor control patterns (electromyography techniques) and reaction forces (force-plate and particle imaging velocimetry techniques) during free walking and swimming in a model amphibious fish. Extracted data will guide material properties testing of both active (muscle) and passive (bone and connective) tissues to test the hypothesis that a changing external force environment influences the safety factor within which animal tissues operate. Quantification of the structural contribution of passive tissues and changing muscle performance through novel ranges of motion will address predictions on how external and internal forces constrain biomechanical performance and, over the longer term, cause plastic tissue responses. Objective 2: Predicting performance through modeling. Experimental data from whole animal and tissue experiments will inform Hill-type and finite element models to map force profiles experienced by fins and body throughout a step/swim cycle. These models will test the hypothesis that bone and muscle morphological plasticity is induced by a change in environmental forces by quantifying the magnitude and orientation of forces that cause tissue plasticity. Objective 3: Quantify the effect of plasticity on performance. Developmental plasticity can dramatically change an animal's form; how this change impacts performance is underexplored. Using our established techniques for raising fish on land, we will link plasticity to functional performance by analyzing changes in behaviour and tissue material properties in land acclimated individuals. Acclimated fish data will test individual tissue/force models (Obj. 2) with a goal to produce an overarching predictive model that includes the effects of plasticity on tissue performance and overall animal function. This research program iteratively uses a diversity of approaches to integrate active tissue behaviour with passive mechanical constraints to explain the adaptive capacity of animal tissues and resulting locomotory performance.