Control properties of single motor units

单电机单元的控制特性

• 批准号: 261869-2009
• 负责人: Collins, David
• 金额: $ 2.55万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=525403
• 关键词: Control; properties; single; motor; units

A motor unit is composed of a motor neuron in the spinal cord, it's axon that travels out to the muscle, and all the muscle fibres it innervates. Motor units provide the only output from the central nervous system to skeletal muscle and thus play a key role in the neural control of movement. Motor units are controlled by descending voluntary commands from the brain and feedback from sensory receptors. Impulses from sensory receptors activate motor units via reflex pathways through the spinal cord. A common way to study the reflex control of motor units is to deliver one or two pulses of electrical stimulation to a peripheral nerve and record the reflex response (H-reflex), mediated through the spinal cord, that returns to the muscle. This technique has provided a wealth of information about human reflexes. During human movement, however, motor units do not receive only one or two impulses along reflex pathways but rather they receive multiple impulses over several seconds. How motor units respond to such repetitive inputs has gone largely unexplored. In addition, motor units often remain active even when the stimulation is turned off, but the mechanisms that underlie these involuntary contractions remains controversial. The short term goals for the experiments described in this proposal are to characterize how motor units respond when they receive physiologically relevant trains of impulses along reflex pathways at different frequencies, intensities and at different levels of voluntary contraction. The long term goals are to identify the mechanisms responsible for: 1) the changes in reflex amplitude that occur during repetitive stimulation and 2) the involuntary muscle contractions that persist after the stimulation has been turned off. The results will identify how motor units respond when they receive inputs along reflex pathways that are more physiologically relevant than have been studied previously (i.e. trains of impulses rather than just one or two impulses). The findings may lead to new way of thinking about the neural control of human motor units.

运动单元由脊髓中的运动神经元组成，它的轴突延伸到肌肉，以及它支配的所有肌肉纤维。运动单元提供中枢神经系统对骨骼肌的唯一输出，因此在运动的神经控制中起关键作用。运动单元是由来自大脑的下行自愿指令和来自感觉受体的反馈控制的。来自感觉受体的脉冲通过脊髓的反射通路激活运动单元。研究运动单元反射控制的一种常用方法是向周围神经传递一到两个电刺激脉冲，并记录反射反应（h反射），通过脊髓调节，返回肌肉。这项技术提供了大量关于人类反射的信息。然而，在人体运动过程中，运动单元并不是沿着反射通路只接收到一两个脉冲，而是在几秒钟内接收到多个脉冲。运动单元对这种重复输入的反应在很大程度上尚未得到探索。此外，即使在刺激关闭时，运动单元也经常保持活跃，但这些不自主收缩的机制仍然存在争议。本实验的短期目标是描述运动单元在不同频率、强度和不同程度的自愿收缩的反射路径上接收到与生理相关的脉冲序列时的反应。长期目标是确定以下机制：1)在重复刺激期间发生的反射振幅变化；2)在刺激关闭后持续存在的不随意肌收缩。研究结果将确定运动单元在接收到比之前研究的更具有生理学相关性的反射通路（即脉冲序列而不仅仅是一个或两个脉冲）时的反应。这一发现可能会导致思考人类运动单元的神经控制的新方法。