Laboratory of Neurophysiology and Movement Biomechanics, Université Libre de Bruxelles, Brussels, Belgium.
Health Division, Fundacion Tecnalia Research and Innovation, San Sebastian, Spain; IKERBASQUE Science Foundation, Bilbao, Spain.
Neuroscience. 2017 Aug 15;357:384-399. doi: 10.1016/j.neuroscience.2017.04.010. Epub 2017 Apr 18.
It is not known whether, during the course of aging, changes occur in the motor strategies used by the CNS for lifting objects of different weights. Here, we analyzed the kinematics of object-lifting in two different healthy groups (young and elderly people) plus one well-known deafferented patient (GL). The task was to reach and lift onto a shelf an opaque cylindrical object with changing weight. The movements of the hand and object were recorded with electromagnetic sensors. In an ecological context (i.e. no instruction was given about movement speed), we found that younger participants, elderly people and GL did not all move at the same speed and that, surprisingly, elder people are faster. We also observed that the lifting trajectories were constant for both the elderly and the deafferented patient while younger participants raised their hand higher when the object weighed more. It appears that, depending on age and on available proprioceptive information, the CNS uses different strategies of lifting. We suggest that elder people tend to optimize their feedforward control in order to compensate for less functional afferent feedback, perhaps to optimize movement time and energy expenditure at the expense of high precision. In the case of complete loss of proprioceptive input, however, compensation follows a different strategy as suggested by GL's behavior who moved more slowly compared to both our younger and older participants.
尚不清楚在衰老过程中，中枢神经系统用于提起不同重量物体的运动策略是否会发生变化。在这里，我们分析了两个不同的健康组（年轻人和老年人）以及一个著名的去传入患者（GL）的物体提起运动的运动学。任务是伸手去拿并将不透明的圆柱形物体抬到架子上，物体的重量不断变化。手和物体的运动由电磁传感器记录。在生态环境中（即没有关于运动速度的指示），我们发现年轻参与者、老年人和 GL 并不都以相同的速度移动，令人惊讶的是，老年人的速度更快。我们还观察到，对于老年人和去传入患者来说，提升轨迹是恒定的，而当物体重量增加时，年轻参与者会将手抬得更高。这表明，中枢神经系统根据年龄和可用的本体感觉信息，使用不同的提升策略。我们认为，老年人倾向于优化其前馈控制，以补偿功能减退的传入反馈，也许是为了优化运动时间和能量消耗，而牺牲高精度。然而，在完全丧失本体感觉输入的情况下，补偿遵循不同的策略，正如 GL 的行为所表明的那样，与我们的年轻和老年参与者相比，GL 的动作速度较慢。
