Anticipatory Control of Digit Kinematics

This study investigated the development of anticipatory control of digit positions in children 5-7, 8-10, and 15-17 years (Groups 1, 2, 3) during a dexterous manipulation task. A modified grip apparatus measured digit forces, positions, and object tilt (i.e., performance) at lift-off. A total of 39 children completed the study. Outputs are provided across 10 trials in 3 different conditions (Left, Right, Center). The data were run through a 5th order low pass Butterworth filter. Force and object roll data were used to compute Tcom, Peak roll, dy (vertical distance between contact points), dLF (difference in load forces), and GF (average grip force). The adolescents modulated their digit placement depending on CM condition similar to young adults, as evidenced by Tcom matching the required external torque and peak roll reducing within several trials, and an adult-like strategy of creating a digit separation (dy) for mechanical advantage. Group 1 began their trials with a higher thumb with minimal change in digit position (dy) across the 10 trials. This group failed to concurrently distribute the load forces (dLF) between their index finger and thumb to apply more load force at the thumb in relation to the index finger. Similarly, Group 2 showed a small change in digit placement across the trials with minimal or no compensation in the load force distribution between the thumb and index finger, although they were successful in one of the 3 conditions.
Adolescents, like adults, used implicit learning to anticipate digit force in parallel with digit positions. However, in children 5-7 years old, implicit learning for anticipatory digit position modulation did not occur. For children 8-10yrs, this learning was only observed in the LCM condition and not to the extent that allowed success in minimizing object roll. Our results suggest a separate, more prolonged timeline for the development of anticipatory mechanisms of digit kinematics than for digit kinetics in children.

本研究探讨了5至7岁、8至10岁以及15至17岁儿童（分为1、2、3组）在进行灵巧操作任务中数字位置前瞻性控制的发育情况。改良式握持装置测量了数字力量、位置以及物体倾斜度（即表现）在提升阶段的参数。共计39名儿童完成了本研究。数据输出跨越了10次试验，在3种不同条件下（左侧、右侧、中心）。数据经过五阶低通巴特沃斯滤波器处理。通过力量和物体滚动数据计算得出Tcom、峰值滚动、dy（接触点之间的垂直距离）、dLF（负载力差异）和GF（平均握力）。青少年根据CM条件调节其数字放置，与年轻人相似，如Tcom与所需的外部扭矩相匹配，峰值滚动在多次试验中减少，以及形成类似成年人的策略，通过创建数字分离（dy）以获得机械优势。第1组在10次试验中开始试验时，拇指高度较高，数字位置（dy）的变化最小。该组未能同时分配负载力（dLF）于食指和大拇指之间，以在拇指相对于食指处施加更大的负载力。同样，第2组在试验中数字放置的变化很小，拇指和食指之间的负载力分配补偿最小或无补偿，尽管他们在3个条件中的1个中表现成功。青少年与成年人一样，利用隐性学习来预测数字力量，与数字位置并行。然而，在5至7岁的儿童中，前瞻性数字位置调节的隐性学习并未发生。对于8至10岁的儿童，这种学习仅在LCM条件下观察到，且程度不足以在最小化物体滚动方面取得成功。我们的结果暗示，在儿童中，数字运动学的前瞻性机制的发展时间线与数字动力学的发展时间线相比更为漫长和复杂。