Manual Dexterity: Age Differences in Cortical Sensorimotor Representations

手动敏捷度：皮质感觉运动表征的年龄差异

• 批准号: 9142468
• 负责人: Patricia A. Reuter-Lorenz
• 金额: $ 46.69万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-30 至 2017-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9142468
• 关键词: Activities of Daily Living; Age; Area; Basic Science; Behavioral; Bilateral; Body part; Brain; Brain imaging; Contralateral; Corpus Callosum; Cutaneous; Data; Data Collection; Diffusion Magnetic Resonance Imaging; Discrimination; Educational Intervention; Effectiveness; Elderly; Exhibits; Fingers; Functional Magnetic Resonance Imaging; Goals; Hand; Health; Imaging Techniques; Independent Living; Individual; Intervention; Ipsilateral; Longevity; Magnetic Resonance Imaging; Manuals; Maps; Measures; Motor; Motor Cortex; Muscle; Performance; Peripheral; Physiological; Process; Productivity; Public Health; Research; Sampling; Sensorimotor functions; Societies; Structure; System; Tactile; Training; Transcranial magnetic stimulation; Video Games; Work; age difference; age related; aged; base; behavior measurement; cortex mapping; dexterity; improved; motor control; neuromechanism; neurophysiology; novel; novel strategies; programs; research study; sensorimotor system; somatosensory; success; young adult

 DESCRIPTION (provided by applicant): There is a fundamental gap in understanding the physiological mechanisms of age differences in manual motor control. This is an important problem given the rapidly increasing older adult segment of our society. The long-term goal of my research program is to identify the neural mechanisms for age-related declines in sensorimotor function, allowing me to develop and evaluate targeted interventions to prolong functional independence for older adults. Our recent work leads to the intriguing and novel hypothesis that age declines in manual motor function are due at least in part to reduced distinctiveness of cortical sensorimotor representations. We have shown that motor cortical representations devoted to a single finger muscle are larger in older than young adults, suggestive of reduced intrahemispheric distinctiveness. We have also shown that motor representations for a single hand extend across both hemispheres for older adults, suggestive of reduced interhemispheric distinctiveness. What remains unknown is 1) whether more expansive and bilateral motor representations result in overlapping motor cortical maps for adjacent body parts and for the two hands; 2) whether reduced distinctiveness underlies age declines in uni- and bimanual dexterity, and 3) whether reduced distinctiveness is restricted to the motor system or also applies to somatosensory representations. Elucidating the mechanisms of age-related decline in manual dexterity and somatosensation is critical because activities of daily living require skilled actions that depend on these sensorimotor processes. Our current objective is to quantify distinctiveness of motor and somatosensory representations within cortical hemispheres (Aim 1) and across cortical hemispheres (Aim 2) in individuals aged 20 - 79 years, with age as a continuous variable. We will also evaluate whether distinctiveness of sensorimotor representations-and manual dexterity-can be improved with a targeted training intervention (Aim 3). Our pilot data provide compelling preliminary evidence that training interventions specifically improve individuated hand control during bimanual actions, and result in altered corpus callosum structure as well as more focal sensorimotor representations. Our novel approach integrates precise behavioral measurements and multiple brain imaging techniques in basic science and intervention-based experiments. If successful, this endeavor will elucidate the underlying mechanisms contributing to age-related declines in sensorimotor function, and has high potential to make a significant impact by extending work productivity and prolonging independent living in older adults.

 描述（由申请人提供）：在理解手动运动控制中年龄差异的生理机制方面存在根本性差距。这是一个重要的问题，因为我们社会中的老年人迅速增加。我的研究计划的长期目标是确定与年龄相关的感觉运动功能下降的神经机制，使我能够开发和评估有针对性的干预措施，以延长老年人的功能独立性。我们最近的工作导致有趣的和新颖的假设，年龄下降的手动运动功能是由于至少部分地减少皮层感觉运动表征的独特性。我们已经表明，运动皮层代表致力于一个单一的手指肌肉是更大的老年人比年轻的成年人，减少半球内的独特性。我们还发现，对于老年人来说，单手的运动表征延伸到两个半球，这表明半球间的独特性降低。目前尚不清楚的是：（1）更广泛的双侧运动表征是否会导致相邻身体部位和双手的运动皮层地图重叠;（2）独特性降低是否是单手和双手灵活性年龄下降的基础;（3）独特性降低是否仅限于运动系统，还是也适用于体感表征。阐明与年龄相关的手的灵活性和躯体感觉下降的机制是至关重要的，因为日常生活活动需要依赖于这些感觉运动过程的熟练动作。我们 目前的目标是量化年龄在20 - 79岁之间的个体在皮质半球内（Aim 1）和跨皮质半球（Aim 2）的运动和躯体感觉表征的独特性，其中年龄作为连续变量。我们还将评估是否可以通过有针对性的训练干预（目标3）来改善感觉运动表征的独特性和手动灵巧性。我们的试点数据提供了令人信服的初步证据， 干预特别改善双手动作期间的个体化手控制，并导致胼胝体结构的改变以及更集中的感觉运动表征。我们的新方法在基础科学和基于干预的实验中集成了精确的行为测量和多种脑成像技术。如果成功，这项奋进将阐明与年龄相关的感觉运动功能下降的潜在机制，并有很大的潜力通过延长工作效率和延长老年人的独立生活来产生重大影响。