Bower Abigail E, Chung Jae Woo, Burciu Roxana G
Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, USA.
Department of Neurology, University of Minnesota Medical School, Minneapolis, MN, USA.
Brain Struct Funct. 2024 Dec 17;230(1):6. doi: 10.1007/s00429-024-02866-5.
Despite the widespread use of older adults (OA) as controls in movement disorder studies, the specific effects of aging on the neural control of upper and lower limb movements remain unclear. While functional MRI paradigms focusing on hand movements are widely used to investigate age-related brain changes, research on lower limb movements is limited due to technical challenges in an MRI environment. This study addressed this gap by examining both upper and lower limb movements in healthy young adults (YA) vs. OA. Sixteen YA and 20 OA, matched for sex, dominant side, and cognitive status, performed pinch grip and ankle dorsiflexion tasks, each requiring 15% of their maximum voluntary contraction. While both groups achieved the target force and exhibited similar force variability and accuracy, OA displayed distinct differences in force control dynamics, with a slower rate of force increase in the hand task and a greater rate of force decrease in the foot task. Imaging results revealed that OA exhibited more widespread activation, extending beyond brain regions typically involved in movement execution. In the hand task, OA showed increased activity in premotor and visuo-motor integration regions, as well as in the cerebellar hemispheres. During the foot task, OA engaged the cerebellar hemispheres more than YA. Collectively, results suggest that OA may recruit additional brain regions to manage motor tasks, possibly to achieve similar performance. Future longitudinal studies that track changes over time could help clarify if declines in motor performance lead to corresponding changes in brain activation.
尽管在运动障碍研究中广泛使用老年人（OA）作为对照，但衰老对上肢和下肢运动神经控制的具体影响仍不清楚。虽然专注于手部运动的功能磁共振成像范式被广泛用于研究与年龄相关的大脑变化，但由于磁共振成像环境中的技术挑战，对下肢运动的研究有限。本研究通过检查健康年轻人（YA）与OA的上肢和下肢运动来填补这一空白。16名YA和20名OA，在性别、优势侧和认知状态方面进行了匹配，执行捏握和踝关节背屈任务，每个任务需要其最大自主收缩的15%。虽然两组都达到了目标力，并且表现出相似的力变异性和准确性，但OA在力控制动力学方面表现出明显差异，手部任务中力增加的速率较慢，足部任务中力下降的速率较大。成像结果显示，OA表现出更广泛的激活，超出了通常参与运动执行的脑区。在手部任务中，OA在前运动和视觉运动整合区域以及小脑半球表现出活动增加。在足部任务期间，OA比YA更多地激活小脑半球。总体而言，结果表明OA可能会招募额外的脑区来管理运动任务，可能是为了达到相似的表现。未来跟踪随时间变化的纵向研究可能有助于阐明运动表现的下降是否会导致大脑激活的相应变化。
