Callegari Bianca, Saunier Ghislain, Duarte Manuela Brito, Almeida Gizele Cristina da Silva, Amorim Cesar Ferreira, Mourey France, Pozzo Thierry, Souza Givago da Silva
Laboratório de Estudos da Motricidade Humana, Universidade Federal do Pará, Belém, Brazil.
Laboratorio de Cognição Motora, Universidade Federal do Pará, Belém, Brazil.
PeerJ. 2018 Mar 15;6:e4309. doi: 10.7717/peerj.4309. eCollection 2018.
Beyond the classical paradigm that presents the Anticipatory Postural Adjustments (APAs) as a manner to create forces that counteract disturbances arising from the moving segment during a pointing task, there is a controversial discussion about the role APAs to facilitate the movement and perform a task accurately. In addition, arm kinematics features are classically used to infer the content of motor planning for the execution and the control of arm movements. The present study aimed to disentangle the conflicting role of APAs during an arm-pointing task in which the subjects reach a central diode that suddenly turns on, while their postural stability was manipulated. Three postures were applied: Standing (Up), Sit without feet support (SitUnsup) and Sit with feet support (SitSup). We found that challenging postural stability induced an increase of the reaction time and movement duration (observed for the SitUnsup compared to SitSUp and Up) as well as modified the upper-limb velocity profile. Indeed, a greater max velocity and a shorter deceleration time were observed under the highest stability (SitSup). Thus, these Kinematics features reflect less challenging task and simple motor plan when the body is stabilized. Concerning the APAs, we observed the presence of them independently of the postural stability. Such a result strongly suggests that APAs act to facilitate the limb movement and to counteract perturbation forces. In conclusion, the degree of stability seems particularly tuned to the motor planning of the upper-limb during a pointing task whereas the postural chain (sitting vs. standing) was also determinant for APAs.
除了经典范式将预期姿势调整（APAs）描述为一种在指向任务中产生力量以抵消运动节段产生的干扰的方式之外，关于APAs在促进运动和准确执行任务方面的作用存在争议性的讨论。此外，手臂运动学特征传统上用于推断手臂运动执行和控制的运动计划内容。本研究旨在厘清在手臂指向任务中APAs的矛盾作用，在该任务中，受试者伸手去够突然亮起的中央二极管，同时操纵他们的姿势稳定性。应用了三种姿势：站立（Up）、无脚支撑坐姿（SitUnsup）和有脚支撑坐姿（SitSup）。我们发现，挑战姿势稳定性会导致反应时间和运动持续时间增加（与SitSup和Up相比，SitUnsup观察到这种情况），并改变上肢速度曲线。事实上，在最高稳定性（SitSup）下观察到更大的最大速度和更短的减速时间。因此，当身体稳定时，这些运动学特征反映出任务挑战性较小且运动计划简单。关于APAs，我们观察到它们的存在与姿势稳定性无关。这样的结果强烈表明，APAs起到促进肢体运动和抵消干扰力的作用。总之，在指向任务中，稳定性程度似乎特别适合上肢的运动计划，而姿势链（坐姿与站姿）对APAs也具有决定性作用。
