Grasping an object naturally or with a tool: are these tasks guided by a common motor representation?
Grasping an object naturally or with a tool: are these tasks guided by a common motor representation?
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DOI：
10.1007/s00221-004-1863-8
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发表时间：
2004-08-01
影响因子：
2
通讯作者：
Stefanini, S
中科院分区：
文献类型：
--
作者：
Gentilucci, M;Roy, AC;Stefanini, S
本研究的目的是确定是否抓取电机动作的运动学参数的控制独立的抓取效应器的生物力学特征。考虑到这一目的，我们比较了自然或使用工具进行的抓握动作。该工具由两个机械手指组成，其打开和闭合阶段分别需要挤压（生物手指的屈曲）和释放（生物手指的伸展）手柄。打开和关闭机械手指所需的力分别大于和小于自然抓取物体所需的力。在对照实验中，参与者用拇指和食指抓住用工具抓住的相同物体。在两个实验中的机械和生物手指以及手臂的运动学相互比较。用该工具抓取物体显示出一些运动学特征与自然抓取的运动学特征惊人地相似，而其他运动学特征则不同。与自然抓握一样，工具抓握包括手指张开和闭合阶段。机械手指的孔径峰值速度和最大孔径随物体尺寸的变化规律与生物手指相同。与此相反，工具掌握不同，从自然的时间方面的运动。最后，初始达到（即加速阶段）的工具使用的影响不大，而最终达到（即减速阶段）延长和更敏感的对象大小。我们讨论了本研究的结果是在有利于的假设，即一些功能的把握电机代表独立于所使用的效应器编码在皮层区域。此外，他们提出了一个部分之间的独立性达到和把握组件。
The aim of the present study was to determine whether kinematic parameters of the grasping motor act are controlled independently of the biomechanical features of the grasping effector. With this purpose in mind, we compared grasping movements performed naturally or using a tool. The tool consisted of two mechanical fingers whose opening and closing phases required squeezing (flexion of the biological fingers) and releasing (extension of the biological fingers) of a handle, respectively. The forces required for opening and closing the mechanical fingers were, respectively, greater and smaller than those used to grasp the objects naturally. In a control experiment the participants grasped with their thumb and index finger the same objects grasped with the tool. The kinematics of the mechanical and biological fingers as well as those of the arm in the two experiments were compared with each other. Grasping an object with the tool showed some kinematic characteristics strikingly similar to those of the natural grasp, whereas others were different. Like the natural grasp, the tool grasp consisted of a finger opening and closing phase. The scaling of both peak velocity of aperture and maximal aperture of the mechanical fingers as a function of object size was the same as that of the biological fingers. In contrast, the tool grasp differed from the natural one for the temporal aspects of the movement. Finally, the initial reach (i.e. the acceleration phase) was poorly influenced by the tool use whereas the final reach (i.e. the deceleration phase) was lengthened and more sensitive to object size. We discuss the results of the present study as being in favour of the hypothesis that some features of the grasp motor representation are coded in cortical areas independently of the used effector. In addition, they suggest a partial independence between the reach and the grasp components.