Not solely a motor: the role of muscles in sensory mechanisms and integrative control
Not solely a motor: the role of muscles in sensory mechanisms and integrative control
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不仅仅是运动：肌肉在感觉机制和综合控制中的作用
DOI：
10.1098/rspb.2022.1491
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Schwaner, M. J.
中科院分区：
文献类型：
--
作者：
Schwaner, M. J.
人们普遍认为肌肉是运动的主要动力，但它作为运动传感器的关键作用却经常被忽视。运动需要跨多个关节的许多肌肉精确而灵活的协调。有节奏运动中的肌肉激活模式是由脊髓神经回路协调的，包括中枢模式发生器和本体感觉反馈。协调运动中的主要运动——肌肉——是一项复杂的任务，因为肌肉必须完成多种机械功能，这些功能会影响我们的运动方式。为了协调机械作用与所需的精确定时，肌肉还充当本体感受器，为神经系统提供姿势和运动的感觉。肌纺锤波是肌肉内的体感受体，为身体提供这种本体感觉。纺锤体感应特性是复杂的，因为它们依赖于特定的运动、力量和对肌肉的运动命令。肌肉力学及其感觉机制的有效整合是强健和适应性运动的关键。肌肉的感知作用在动态条件下尤其重要，例如在崎岖地形中行走或从扰动中恢复，因为肌肉的机械反应取决于环境、内在力学和感觉反馈之间的动态相互作用（图1）。肌肉需要关于其状态的快速和精确的信息，以便在运动中有效地在必要的机械角色之间切换。尽管具有明显的重要性，但在自然运动中，肌肉在本体感觉中的感觉作用仍然知之甚少。Kissane等人最近的一项研究调查了肌肉纺锤体丰度、肌肉结构和运动动力学之间的关系。这项研究使用了个体特异性医学成像和人类参与者小腿肌肉骨骼模型的新组合。使用医学成像来估计肌肉质量和纤维长度，并根据肌肉质量和平均文献数据估计肌肉纺锤体密度。作者使用肌肉骨骼模型来估计肌肉的功输出，并根据每个参与者在步行过程中的个人运动学和动力学模式，分配每块肌肉的机械作用。模型分析共包括23个单独的肌肉，跨越了估计的肌肉纺锤体丰度范围。作者发现，肌肉纺锤体的绝对数量与肌纤维长度有关，可以预测肌肉总长度及其速度分布，并在一定程度上预测步行时肌肉的发力能力。他们的研究结果表明，肌肉机械作用和纺锤体丰度之间存在有趣的相关性。作者得出结论，具有较高估计主轴密度的肌肉主要作为弹簧，而具有较低主轴丰度的肌肉在稳定行走任务中起制动作用。这项工作强调了在运动中有效控制肌肉的综合传感和机械动作的重要性。研究运动任务中肌肉形态、感知功能和运动力学之间复杂的相互作用是具有挑战性的，因为许多特征不能直接测量。虽然对人类受试者的研究有许多优点，结果有许多重要的应用，但由于伦理约束，在人类受试者中可以采取的直接措施存在重要的局限性。Kissane等人的研究
Muscles are widely appreciated as the main motors in movement, but their critical role as sensors in movement is often neglected. Locomotion requires precise yet flexible coordination of many muscles across multiple joints. Muscle activation patterns in rhythmic movements are coordinated by spinal neural circuits that include central pattern generator and proprioceptive feedback. Orchestrating the primary motor in movement—muscle—is a complex task because muscles must fulfil multiple mechanical functions, which influence how we move [1]. To coordinate mechanical roles with the precision timing required, muscles also act as proprioceptors to provide the nervous system with a sense of posture and motion. Muscle spindles are within-muscle somatosensory receptors that provide the body with this sense of proprioception. Spindle sensing properties are complex as they depend on the specific movement, forces and motor commands to the muscle. The effective integration of muscle mechanics and its sensory mechanisms is key to robust and adaptable locomotion. The sensing role of muscle is especially important under dynamic conditions, such as walking in rough terrain or recovering from perturbations, because the muscle’s mechanical response depends on the dynamic interplay between the environment, intrinsic mechanics and sensory feedback (figure 1). Muscles require rapid and precise information about their state to effectively switch among the necessary mechanical roles in movement. Despite the apparent importance, the sensory role of muscle in proprioception in natural movements remains poorly understood. A recent study by Kissane et al.[2] investigated the relationship between muscle spindle abundance, muscle architecture and movement dynamics. This study used a novel combination of individual-specific medical imaging and musculoskeletal modelling of the lower leg in human participants. Medical imaging was used to estimate muscle mass and fibre lengths, and to estimate muscle spindle density based on muscle mass and averaged literature data. The authors used the musculoskeletal models to estimate muscle work output and assign each muscle a mechanical role, based on each participant’s individual kinematic and kinetic patterns during walking. The model analysis included a total of 23 individual muscles, spanning a range of estimated muscle spindle abundance. The authors found that the absolute number of muscle spindles was related to muscle fibre length, and predictive of total muscle length, its velocity profile, and to a certain extent to the force-generating capacity of muscles during walking [2]. Their findings suggest an intriguing correlation between muscle mechanical roles and spindle abundance. The authors concluded that muscles with higher estimated spindle densities operate predominantly as springs, whereas muscles with lower spindle abundance function as brakes during steady walking tasks. This work highlights the importance of integrated sensing and mechanical action for effective control of muscles in movement. Studying the complex interactions between muscle morphology, sensing function and mechanics of movement during locomotor tasks is challenging because many features cannot be measured directly. While studies on human participants present many advantages and results have many important applications, there are important limitations on direct measures that can be made in human subjects due to ethical constraints. The study by Kissane et al.[2]
DOI：
10.1016/s1095-6433(02)00244-1
发表时间：
2002-12-01
影响因子：
2.3
作者：
Roberts, TJ
通讯作者：
Roberts, TJ
DOI：
--
发表时间：
2000-12
期刊：
The Journal of experimental biology
影响因子：
--
作者：
G. Gillis;A. Biewener
通讯作者：
G. Gillis;A. Biewener