Motor Unit Discharge and Slowed Motor Output in Elderly

描述(申请人提供)：老年人经常在精准的任务中控制不好而感到沮丧，肌肉力量产生较慢在防止跌倒方面具有特别重要的意义。运动单位的研究迫切需要扩展的范例，以提供关于现实世界任务中控制机制的新信息。我们将检验两种相关运动单位放电行为的年龄相关差异，并提供可用于改善老年人和患者群体运动质量的信息。目标1是关于在正弦等长收缩的精确控制中的速率编码。据推测，老年人的放电率调制幅度较小，可能是由于老化的肌肉纤维收缩能力减慢的抽动总和增强所致。目标2是关于静息和次最大力量水平快速产生力量时运动单位的放电行为。据推测，在快速收缩的开始期间，与年轻人相比，老年运动单位的初始放电速度会更慢，双重放电也会更少。运动单位和肌力记录、表面肌电和收缩特性将从20名年轻人(&lt；30岁)和20名老年人(&gt；65岁)的第一背骨间肌肉中获得。在这些条件下成功的实验可以被认为是运动单元研究的重大进步。除了在运动单元水平上进一步了解正常老化之外，该项目还将提供有关运动单元放电行为的大量新信息。例如，考虑：1)这一标准化数据对患者群体中类似研究的价值，以及2)更好地了解健康个体的神经命令可以帮助改善瘫痪肌肉的功能性电刺激。该项目还为未来研究这些神经因素和功能在老年人和患者群体中的适应性提供了基础。

DESCRIPTION (provided by applicant): The elderly are often frustrated by poor control during precision tasks, and slower production of muscular force has specific importance in fall prevention. Motor unit research is in dire need of expanded paradigms to provide new information about control mechanisms during real-world tasks. We will examine age-related differences in two relevant motor unit discharge behaviors and provide information that can be used to improve movement quality in older adults and also in patient populations. Aim 1 is about rate coding during the precise control of sinusoidal isometric contractions. It is hypothesized that that the amplitude of firing rate modulation is less in older adults, perhaps due to enhanced twitch summation of aged muscle fibers with slowed contractility. Aim 2 is about motor unit discharge behavior during rapid force production from rest as well as from a submaximal force level. It is hypothesized that during the initiation of rapid contractions, the initial firing rates of aged motor units will be slower and there will be fewer doublet discharges, as compared to young adults. Motor unit and muscular force recordings, surface electromyography and contractile properties will be obtained from the first dorsal interosseous muscle of 20 young (<30 years) and 20 older (>65 years) adults. Successful experiments in these conditions can be considered significant progress in motor unit research. In addition to furthering knowledge of normal aging at the level of the motor unit, this project will provide vast new information about motor unit discharge behavior in general. Consider for example: 1) the value of this normative data for similar research in patient populations, and 2) a better knowledge of neural commands in healthy individuals can help to improve the functional electrical stimulation of paralyzed muscle. This project also provides the basis for future research on the adaptability of these neural factors and function in older adults and patient populations.