Sympathetic Nerve Activity and Fine Motor Skills

描述(由申请人提供)：这项研究的总体目的是检查交感神经系统的活动增强是否会损害个体执行精细运动技能的能力。这项拟议的研究代表了一项新的研究，将调查人类自主神经系统和运动系统之间尚未探索的功能联系。对于患有心脏病或年龄较大的人来说，手动灵活性受到影响，他们通常具有高水平的基础肌肉交感神经活动(MSNA)。这种削弱的手工灵活性可能会导致生活质量和独立生活能力的下降。独立研究表明，在人类手部肌肉稳定的低水平收缩期间，精神压力会增加MSNA和力量波动。然而，没有研究直接将增强的MSNA与力波动联系起来。此外，有证据表明，由于SNA的升高，LA传入回路的敏感性增加，并且LA传入回路的敏感性与人体的力波动之间存在关联。因此，我们假设交感神经系统的活动增强会通过改变LA传入回路的敏感度来损害个体执行精细运动技能的能力。这项建议的具体目的是确定增加的MSNA是否增加了力量波动(目标1)，并检查增加的MSNA是否改变了手部肌肉在低力收缩时的传入回路(目标2)的敏感性。为了达到这些目的，在对下半身施加负压(LBNP)的实验操作中，将测量MSNA、力量波动、单运动单位活动、伸展反射和手肌肉稳定收缩期间的H反射。这项研究的发现将构成关于心血管疾病患者手工灵活性受损的生理机制的新信息。初步发现将为R01的应用奠定基础，该应用将进一步确定导致心血管疾病患者或有心血管疾病风险的个人精细运动技能受损的生理机制。这项研究的结果将导致制定干预措施，以改善这些人受损的手工灵活性。

DESCRIPTION (provided by applicant): The general aim of this research is to examine whether enhanced activity of the sympathetic nervous system impairs the ability of individuals to perform fine motor skills. The proposed research represents a novel study that will investigate an unexplored functional connection between the autonomic nervous system and the motor system in humans. Manual dexterity is compromised in individuals with cardiac disease or with advanced age, who often have high levels of basal muscle sympathetic nerve activity (MSNA). This impaired manual dexterity may lead to a decrease in quality of life and capability for independent living. Independent research studies indicate that mental stress increases MSNA and force fluctuations during steady low-level contractions of hand muscles in humans. However, there are no studies that directly link enhanced MSNA with force fluctuations. Furthermore, there is evidence that suggests an increase in sensitivity of the la afferent circuit due to heightened SNA, and associations between the sensitivity of the la afferent circuit and force fluctuations in humans. Hence, we hypothesize that enhanced activity of the sympathetic nervous system impairs the ability of individuals to perform fine motor skills by altering the sensitivity of the la afferent circuit. The specific aims of this proposal are to determine whether increased MSNA increases force fluctuations (Aim 1), and to examine whether increased MSNA alters the sensitivity of the la afferent circuit (Aim 2) during low-force contractions of a hand muscle. To achieve these aims, MSNA, force fluctuations, single motor unit activity, stretch reflex, and H-reflex during steady contractions of a hand muscle will be measured when MSNA is experimentally manipulated by applying negative pressure to the lower body (LBNP). The findings of this study will constitute new information about the physiological mechanisms that impair manual dexterity in individuals with cardiovascular disease. The preliminary findings will form the foundation for an R01 application that will further identify the physiological mechanisms contributing to the impairment of fine motor skills in individuals who have or who are at risk of cardiovascular disease. The outcome of the study will lead to the development of interventions that can ameliorate the impaired manual dexterity in those individuals.