Visuomotor contributions to unsteadiness in frail aging

描述(由申请人提供)：老年人对肌肉力量的控制受损会对生活质量产生负面影响。肌肉对运动神经元池的各种输入可能有助于改变健康和虚弱老年人的力量控制。视觉运动对力量不稳定的贡献在健康老年人中没有很好的特征，而在虚弱的老年人中则未知。现有的有限信息仅适用于手部较小的肌肉。其目的是：1)确定视觉运动矫正对同一青年、健康老年人和虚弱老年人手部肌肉(FDI)和腿部近端肌肉(KE)力量波动的贡献，2)量化中枢减慢和皮肤感觉敏度在受损对照中的作用，3)确定手部和腿部肌肉力量波动的功能意义，以及4)确定视觉运动对FDI和KE运动单位放电变异性的贡献。年轻、健康的老年人和虚弱的老年人将在不同的视觉反馈条件下进行稳定的收缩，以确定与年龄相关的视觉运动信息处理的差异，以保持稳定的肌肉力量。反应时间和感觉敏锐度测试将确定中枢减速和感觉退化的贡献。手部灵巧度和腿部功能测量将提供临床上与功能相关的联系。单个运动单位的放电将被记录在fDi和KE肌肉中，以提供关于两个非常不同的肌肉中的力波动和随年龄变化的神经机制的信息。尽管虚弱的老年人表现出神经肌肉和功能下降，但这一组的力量控制机制尚不清楚。我们假设，虚弱的老年人将表现出更大的视觉运动处理贡献，更大的力量波动和更大的运动单位变异性，这将部分地由中枢减慢和感觉退化来解释。这个项目将确定老年人控制肌肉更困难的一些原因。将测量年轻、健康的老年人和虚弱的老年人对不同肌肉的控制，以确定视力受损在肌肉控制中的作用。更多地了解老年美国人神经系统的这些变化，可以导致应用更有效的干预策略来对抗老年人的虚弱和功能障碍。

DESCRIPTION (provided by applicant): The impaired control of muscle force in elderly adults can negatively impact quality of life. Various inputs to the motor neuron pool for a muscle could contribute to altered force control for healthy and frail elderly. The visuomotor contribution to force unsteadiness is not well characterized in healthy elderly and unknown in frail elderly. The limited information available is only for small hand muscles. The purposes are 1) to determine the contribution of visuomotor correction to force fluctuations in a hand muscle (FDI) and proximal leg muscle (KE) within the same individual young, health elderly, and frail elderly adults, 2) to quantify the role of central slowing and cutaneous sensory acuity in the impaired control, 3) to determine the functional significance of hand and leg muscle force fluctuations, and 4) to determine the visuomotor contribution to the variability of FDI and KE motor unit discharge. Young, healthy elderly and frail elderly adults will perform steady contractions under different visual feedback conditions to determine age-related differences in the processing of visuomotor information to maintain a steady muscle force. Reaction time and sensory acuity tests will determine the contribution of central slowing and sensory degradation. Hand dexterity and leg functional measures will provide a clinically relevant connection to function. The discharge of single motor units will be recorded in the FDI and KE muscles to provide information on a neural mechanism underlying the force fluctuations and changes with aging in two very different muscles. Although frail elderly adults exhibit neuromuscular and functional decline, mechanisms of force control in this group are not well understood. We hypothesize that frail elderly will exhibit a greater contribution of visuomotor processing, greater fluctuations in force, and greater motor unit variability, which will be explained in part by central slowing and sensory degradation. This project will determine some reasons that the elderly have more difficulty controlling their muscles. The control of different muscles will be measured in young, healthy elderly, and frail elderly adults to determine the role of impaired vision in the control of muscles. Greater knowledge of these changes in the nervous system of aging Americans can lead to the application of more effective intervention strategies to combat frailty and functional disability in the elderly.