Sympathetic Nerve Activity and Fine Motor Skills

描述（由申请人提供）：本研究的总体目的是检查交感神经系统活动的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未探索的功能联系。患有心脏病或高龄的个体的手动灵活性受到损害，这些个体通常具有高水平的基底肌交感神经活动（MSNA）。这种手部灵活性受损可能导致生活质量和独立生活能力下降。独立的研究表明，精神压力会增加MSNA和人类手部肌肉稳定低水平收缩期间的力量波动。然而，没有研究表明，直接联系增强MSNA与力的波动。此外，有证据表明，由于SNA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类的力波动之间存在关联。因此，我们假设交感神经系统活动的增强通过改变左心房传入回路的敏感性来损害个体执行精细运动技能的能力。这个建议的具体目的是确定是否增加MSNA增加力的波动（目的1），并检查是否增加MSNA改变的敏感性la传入回路（目的2）在低力收缩的手肌肉。为了实现这些目标，MSNA，力波动，单运动单位活动，牵张反射，和H反射在手部肌肉的稳定收缩将被测量时，MSNA是通过施加负压下半身（LBNP）实验操作。这项研究的结果将构成新的信息的生理机制，损害手的灵活性，在个人与心血管疾病。初步研究结果将为R01应用奠定基础，该应用将进一步确定导致患有心血管疾病或有心血管疾病风险的个体精细运动技能受损的生理机制。这项研究的结果将导致干预措施的发展，可以改善这些人的手灵活性受损。

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.