Visuomotor contributions to unsteadiness in frail aging

描述（由申请人提供）：老年人肌肉力量控制受损会对生活质量产生负面影响。对肌肉运动神经元池的各种输入可能有助于改变健康和虚弱的老年人的力量控制。视觉运动对力失稳的贡献在健康老年人中尚未很好地表征，而在体弱老年人中尚不清楚。有限的信息只能用于手部的小肌肉。目的是：1)确定视觉运动矫正对同一个体（年轻人、健康老年人和体弱老年人）手部肌肉（FDI）和腿近端肌肉（KE）力波动的贡献；2)量化中枢慢化和皮肤感觉敏锐度在控制受损中的作用；3)确定手部和腿部肌肉力波动的功能意义。4)确定视觉运动对FDI和KE运动单元放电变异性的贡献。年轻、健康老年人和体弱老年人在不同的视觉反馈条件下进行稳定收缩，以确定视觉运动信息加工的年龄相关差异，以维持稳定的肌肉力量。反应时间和感觉敏锐度测试将决定中枢反应减慢和感觉退化的贡献。手部灵巧度和腿部功能测量将提供与功能相关的临床联系。将记录FDI和KE肌肉中单个运动单元的放电，以提供两种完全不同的肌肉中随年龄变化的力波动和变化的神经机制的信息。虽然虚弱的老年人表现出神经肌肉和功能衰退，但这一群体的力量控制机制尚不清楚。我们假设，体弱多病的老年人将表现出更大的视觉运动加工贡献，更大的力量波动和更大的运动单位变异性，这将部分解释为中枢减慢和感觉退化。这个项目将确定老年人更难控制肌肉的一些原因。将测量年轻人、健康老年人和体弱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。对美国老年人神经系统的这些变化有了更多的了解，就可以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.