The Department of Psychology, Nanjing University, Nanjing 210046, People's Republic of China.
Department of Psychology, The University of British Columbia, Vancouver, British Columbia, Canada; The Brain and Mind Institute, The University of Western Ontario, London, Ontario, Canada.
Cognition. 2016 Jun;151:28-36. doi: 10.1016/j.cognition.2016.02.013. Epub 2016 Mar 3.
A central question in sensorimotor control is whether or not actions performed with the hands and corresponding actions performed with tools share a common underlying motor plan, even though different muscles and effectors are engaged. There is certainly evidence that tools used to extend the reach of the limb can be incorporated into the body schema after training. But even so, it is not clear whether or not actions such as grasping with tools and grasping with the fingers share the same programming network, i.e. show 'motor equivalence'. Here we first show that feedback-appropriate motor programming for grasps with atypical hand postures readily transfers to stereotypical precision grasps. In stark contrast, however, we find no evidence for an analogous transfer of the programming for grasps using tools to the same stereotypical precision grasps. These findings have important implications for our understanding of body schema. Although the extension of the limb that is afforded by tool use may be incorporated into the body schema, the programming of a grasping movement made with tools appears to resist such incorporation. It could be the case that the proprioceptive signals from the limb can be easily updated to reflect the end of a tool held in the hand, but the motor programs and sensory signals associated with grasping with the thumb and finger cannot be easily adapted to control the opening and closing of a tool. Instead, new but well-practiced motor programs are put in place for tool use that do not exhibit motor equivalence with manual grasping.
在感觉运动控制中，一个核心问题是，即使使用不同的肌肉和效应器，用手完成的动作和用工具完成的相应动作是否共享一个共同的潜在运动计划。当然，有证据表明，经过训练后，用于延长肢体伸展范围的工具可以被纳入身体图式。但即便如此，仍不清楚使用工具进行抓握和用手指进行抓握等动作是否共享相同的编程网络，即表现出“运动等价性”。在这里，我们首先表明，适用于非典型手姿抓握的反馈适当运动编程可以很容易地转移到典型的精确抓握中。然而，形成鲜明对比的是，我们没有发现使用工具进行抓握的编程向相同的典型精确抓握进行类似转移的证据。这些发现对我们理解身体图式具有重要意义。虽然工具使用所提供的肢体延伸可以被纳入身体图式，但使用工具进行抓握运动的编程似乎抵制这种纳入。可能是因为来自肢体的本体感觉信号很容易被更新以反映手中持有的工具的末端，但与用拇指和手指抓握相关的运动程序和感觉信号不能轻易适应来控制工具的开合。相反，新的但经过良好实践的运动程序被用于工具使用，这些程序与手动抓握不表现出运动等价性。
