Plasticity of human motoneurone properties

人类运动神经元特性的可塑性

• 批准号: 105424-2006
• 负责人: Garland, Jayne
• 金额: $ 1.86万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=390868
• 关键词: Plasticity; human; motoneurone; properties

Motor control research using animal models has helped establish relations between properties of the motoneurone and the muscle fibers that it innervates.  In humans, Matthews (1996) developed a model for estimating one of the motoneurone properties (afterhyperpolarization (AHP) time-course).  This model represents one of the only windows to view the properties of motoneurones in humans.  The time-course of the AHP influences the capacity of the motoneurone to discharge action potentials and, thereby, the force produced by the muscle.  The adaptability of the AHP has not been thoroughly investigated in animal models and is virtually unexplored in humans.  The proposed research will determine the capacity of synaptic input to modify the time-course of the motoneurone AHP in humans.  We will study three synaptic inputs in separate experiments: cutaneous (skin) input, muscle spindle input, and input from group III-IV afferents activated by muscle fatigue.  Low-force contractions with the ankle dorsiflexor muscles (tibialis anterior) will be held for 30 min: 10 min before, during, and after the addition of synaptic input, with the motoneurone AHP being calculated in each phase from a train of motor unit potentials collected with a fine wire electrode.  Either a non- painful cutaneous stimulus will be applied to the skin overlying tibialis anterior, or vibration will be applied to the tibialis anterior tendon, or the muscle will be fatigued by performing a low-force contraction under ischemic conditions.  Healthy adult volunteers and volunteers with unilateral motor paresis after stroke will participate in the study.  This research program will advance our understanding of human motoneurone properties when they are activated voluntarily with both descending commands and sensory inputs.  This research will have far-reaching implications for motor control mechanisms that have not been investigated to date, primarily because the corresponding animal experiments do not involve voluntary contractions.  The acquired knowledge will contribute to our understanding of motor control disorders and whether sensory inputs may be useful in modifying motoneurone properties after a neurological insult, such as a stroke.

使用动物模型进行的运动控制研究有助于建立运动神经元的特性与其所支配的肌肉纤维之间的关系。马修斯（1996）开发了一个模型，用于估计运动神经元的属性之一（后超极化（AHP）时程）。该模型代表了观察人类运动神经元特性的仅有的窗口之一。AHP的过程影响运动神经元释放动作电位的能力，从而，肌肉产生的力量。AHP的适应性在动物模型中还没有得到彻底的研究，在人类中也几乎没有探索。拟议的研究将确定突触输入修改时间的能力，我们将在单独的实验中研究三种突触输入：皮肤（皮肤）输入，肌梭输入，以及由肌肉疲劳激活的第III-IV组传入的输入。踝背屈肌的低力收缩（胫骨前肌）将保持30分钟：在添加突触输入之前、期间和之后10分钟，其中运动神经元AHP在每个阶段中从用细线电极收集的一系列运动单元电位计算。疼痛的皮肤刺激将被施加到覆盖胫骨前肌的皮肤，或者振动将被施加到胫骨前肌腱，或者肌肉会因为低强度的在缺血条件下的强制收缩。健康成年志愿者和中风后单侧运动麻痹的志愿者将参与这项研究。这项研究计划将推进我们对人类运动神经元在下行命令和感觉输入下自发激活时的特性的理解。这项研究将对迄今尚未研究的运动控制机制产生深远的影响，主要是因为相应的动物实验不涉及自主收缩。获得的知识将有助于我们了解运动控制障碍，以及是否感觉输入可用于在神经损伤（例如中风）后改变运动神经元的性质。