Octopuses use a human-like strategy to control precise point-to-point arm movements
Octopuses use a human-like strategy to control precise point-to-point arm movements
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DOI：
10.1016/j.cub.2006.02.069
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发表时间：
2006-04-18
期刊：
影响因子：
9.2
通讯作者：
Hochner, B
中科院分区：
文献类型：
--
作者：
Sumbre, G;Fiorito, G;Hochner, B
通过协调来控制或减少运动自由度是电机控制的关键问题之一。这一问题在四肢极度冗余的情况下尤为突出，比如章鱼[2]极其灵活的手臂。对于人类点对点手臂运动，已经提出了几种简化这些控制问题的策略[3-6]。尽管存在进化差距和形态差异，人类和章鱼在将食物送到嘴里时进化出了相似的策略。为了实现这种精确的点对点任务，章鱼臂产生了一个基于三个动态关节的准关节结构。这些关节周围的旋转运动将物体送入口腔。在这里，我们描述了一种外周神经机制——两波肌肉激活相互传播，它们的碰撞点决定了关节内侧的位置。这是一个非常简单的机制，可以根据物体被抓住的位置来调整片段的长度。此外，与某些人类手臂运动类似，在关节水平而不是末端执行器水平观察到运动学不变量，这表明内在的控制协调。进化收敛到相似的几何和运动学特征表明，在关节空间水平上控制运动约束的关节肢体是精确点对点运动的最优解。
One of the key problems in motor control is mastering or reducing the number of degrees of freedom (DOFs) through coordination [1]. This problem is especially prominent with hyper-redundant limbs such as the extremely flexible arm of the octopus [2]. Several strategies for simplifying these control problems have been suggested for human point-to-point arm movements [3-6]. Despite the evolutionary gap and morphological differences, humans and octopuses evolved similar strategies when fetching food to the mouth. To achieve this precise point-to-point-task, octopus arms generate a quasi-articulated structure based on three dynamic joints. A rotational movement around these joints brings the object to the mouth [7]. Here, we describe a peripheral neural mechanism-two waves of muscle activation propagate toward each other, and their collision point sets the medial-joint location. This is a remarkably simple mechanism for adjusting the length of the segments according to where the object is grasped. Furthermore, similar to certain human arm movements, kinematic invariants were observed at the joint level rather than at the end-effector level, suggesting intrinsic control coordination. The evolutionary convergence to similar geometrical and kinematic features suggests that a kinematically constrained articulated limb controlled at the level of joint space is the optimal solution for precise point-to-point movements.