IIT@UniFe Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, via Fossato di Mortara 17/19, 44121, Ferrara, Italy.
Department of Psychology, University of Milano-Bicocca, Milan, Italy.
Sci Rep. 2023 May 22;13(1):8264. doi: 10.1038/s41598-023-34861-x.
The observation that different effectors can execute the same movement suggests functional equivalences driven by limb independent representation of action in the central nervous system. A common invariant motor behavior is the speed and curvature coupling (the 1/3 power law), a low dimensional (abstract) descriptor of movement which is resilient to different sensorimotor contexts. Our purpose is to verify the consistency of such motor equivalence during a drawing task, by testing the effect of manual dominance and movement speed on motor performance. We hypothesize that abstract kinematic variables are not the most resistant to speed or limb effector changes. The results show specific effects of speed and hand side on the drawing task. Movement duration, speed-curvature covariation, and maximum velocity were not significantly affected by hand side, while geometrical features were strongly speed and limb dependent. However, intra-trial analysis performed over the successive drawing movements reveals a significant hand side effect on the variability of movement vigor and velocity-curvature relationship (the 1/3 PL). The identified effects of speed and hand dominance on the kinematic parameters suggest different neural strategies, in a pattern that does not go from the most abstract to the least abstract component, as proposed by the traditional hierarchical organization of the motor plan.
不同效应器可以执行相同运动的观察结果表明，中枢神经系统中对动作的独立于肢体的表示驱动了功能等效性。一种常见的不变运动行为是速度和曲率耦合（1/3 幂律），这是一种对不同感觉运动情境具有弹性的低维（抽象）运动描述符。我们的目的是通过测试手动优势和运动速度对运动表现的影响，在绘图任务中验证这种运动等效性的一致性。我们假设抽象运动变量不是最能抵抗速度或肢体效应器变化的变量。结果表明，速度和手侧对绘图任务有特定的影响。运动持续时间、速度-曲率协变和最大速度不受手侧的显著影响，而几何特征则强烈依赖于速度和肢体。然而，在对连续的绘图运动进行的试验内分析中，发现运动活力和速度-曲率关系（1/3PL）的变异性在手侧上有显著影响。速度和手优势对运动参数的影响表明，存在不同的神经策略，这与传统的运动计划层次结构所提出的从最抽象到最不抽象的模式并不一致。
