Kitchen Nick M, Miall R Chris
School of Psychology, University of Birmingham, Birmingham, UK.
Department of Speech and Hearing Science, University of Washington, Seattle, WA, USA.
Exp Brain Res. 2019 Feb;237(2):531-545. doi: 10.1007/s00221-018-5440-y. Epub 2018 Nov 26.
During normal healthy ageing there is a decline in the ability to control simple movements, characterised by increased reaction times, movement durations and variability. There is also growing evidence of age-related proprioceptive loss which may contribute to these impairments. However, this relationship has not been studied in detail for the upper limb. We recruited 20 younger adults (YAs) and 31 older adults (OAs) who each performed 2 tasks on a 2D robotic manipulandum. The first assessed dynamic proprioceptive acuity using active, multi-joint movements constrained by the robot to a pre-defined path. Participants made perceptual judgements of the lateral position of the unseen arm. The second task required fast, accurate and discrete movements to the same targets in the absence of visual feedback of the hand, and without robotic intervention. We predicted that the variable proprioceptive error (uncertainty range) assessed in Task 1 would be increased in physically inactive OAs and would predict increased movement variability in Task 2. Instead we found that physically inactive OAs had larger systematic proprioceptive errors (bias) than YAs (t[33] = 2.8, p = 0.009), and neither proprioceptive uncertainty nor bias was related to motor performance in either age group (all regression model R ≤ 0.06). We suggest that previously reported estimates of proprioceptive decline with ageing may be exaggerated by task demands and that the extent of these deficits is unrelated to control of discrete, rapid movement. The relationship between dynamic proprioceptive acuity and movement control in other tasks with greater emphasis on online feedback is still unclear and warrants further investigation.
在正常健康衰老过程中，控制简单动作的能力会下降，其特征是反应时间、动作持续时间和变异性增加。越来越多的证据表明，与年龄相关的本体感觉丧失可能导致这些功能障碍。然而，上肢的这种关系尚未得到详细研究。我们招募了20名年轻成年人（YAs）和31名年长成年人（OAs），他们每人在二维机器人操作器上执行两项任务。第一项任务使用受机器人约束在预定义路径上的主动多关节运动来评估动态本体感觉敏锐度。参与者对未看到的手臂的横向位置进行感知判断。第二项任务要求在没有手部视觉反馈且无机器人干预的情况下，快速、准确且离散地移动到相同目标。我们预测，在任务1中评估的可变本体感觉误差（不确定范围）在身体不活跃的年长成年人中会增加，并会预测任务2中运动变异性的增加。相反，我们发现身体不活跃的年长成年人比年轻成年人有更大的系统性本体感觉误差（偏差）（t[33] = 2.8，p = 0.009），并且在两个年龄组中，本体感觉的不确定性和偏差均与运动表现无关（所有回归模型R≤0.06）。我们认为，先前报道的随着年龄增长本体感觉下降的估计可能被任务要求夸大了，并且这些缺陷的程度与离散、快速运动的控制无关。在其他更强调在线反馈的任务中，动态本体感觉敏锐度与运动控制之间的关系仍不清楚，值得进一步研究。
