Institut des Sciences du Mouvement, EJ Marey, UMR 6233, Université de la Méditerranée et CNRS, Marseille, France.
Gerontology. 2012;58(2):171-80. doi: 10.1159/000329347. Epub 2011 Jul 20.
Measurement of changes in human information-processing capacities underlying slowing of sensorimotor processes is an important challenge for aging research. Methods exist to estimate the magnitude of slowing and variability coefficients, but attempts to apply them in motor tasks have been scarce. In the present experiment we combined movement kinematic analysis, efficiency functions and Brinley plot to assess age-related slowing and variability of sensorimotor processes in a discrete Fitts' aiming task.
(1) Quantifying slowing and variability for the different sensorimotor processes involved in aiming movements, and (2) determining whether changes occurred continuously over time by comparing different age groups.
29 participants (24-90 years) divided into four age groups were tested. Target size manipulation resulted in three levels of difficulty. Total movement time, durations of the first and secondary movement phases and related variability were analyzed. Fitts and Brinley regression functions were calculated on the basis of the different movement variables.
Only older participants were slower than the three younger age groups. For this group, age-difficulty effect was observed for total movement times, but analyses showed that only the secondary movement phase slowed multiplicatively. Additive and proportional increases in variability were also observed in older participants for the first and secondary movement phases, respectively. For the secondary movement phase, estimated slowing coefficients were comparable to those reported in cognitive literature. In addition, Brinley analyses showed that variability increased more than movement time in the secondary movement phase.
Combination of the different methods of analysis allowed a precise assessment of the locus of slowing and variability of sensorimotor processes in the different movement phases. Results showed that significant changes in both slowing and variability of the different processes occurred late in life. Our findings also suggest that slowing could result from age-induced increase in noise produced by the neural system. Finally, the present results raise the question of whether age-related slowing and increase in variability observed in both cognitive and sensorimotor domains share common causes in the central nervous system.
测量人类信息处理能力的变化，这些变化是导致感觉运动过程减缓的原因，这是衰老研究的一个重要挑战。虽然存在估计减缓幅度和变异系数的方法，但在运动任务中应用这些方法的尝试很少。在本实验中，我们结合运动运动学分析、效率函数和 Brinley 图来评估离散 Fitts 瞄准任务中与感觉运动过程相关的老化和变异性。
(1)量化瞄准运动中不同感觉运动过程的减缓和变异性，(2)通过比较不同年龄组来确定变化是否随时间连续发生。
29 名参与者（24-90 岁）分为四组进行测试。目标大小的操作导致了三个难度级别。分析了总运动时间、第一和第二运动阶段的持续时间以及相关的变异性。根据不同的运动变量计算了 Fitts 和 Brinley 回归函数。
只有年长的参与者比三个年轻的年龄组慢。对于这个组，观察到了总运动时间的年龄难度效应，但分析表明，只有第二运动阶段呈倍数减慢。对于第一和第二运动阶段，年长的参与者也观察到了变异性的附加和比例增加。对于第二运动阶段，估计的减缓系数与认知文献中报告的相似。此外，Brinley 分析表明，在第二运动阶段，变异性的增加超过了运动时间的增加。
不同分析方法的结合允许对不同运动阶段的感觉运动过程的减缓和变异性的位置进行精确评估。结果表明，在生命后期，不同过程的减缓和变异性都发生了显著变化。我们的研究结果还表明，减缓可能是由于神经系统产生的噪声随年龄增长而增加所致。最后，本研究结果提出了一个问题，即在认知和感觉运动领域观察到的与年龄相关的减缓和变异性是否在中枢神经系统中具有共同的原因。
