MANIBUS Laboratory, Psychology Department, University of Turin, Turin, Italy.
School of Health Sciences, HES-SO Valais-Wallis, Sion, Switzerland.
Neuropsychologia. 2020 Nov;148:107622. doi: 10.1016/j.neuropsychologia.2020.107622. Epub 2020 Sep 6.
In everyday life, we constantly act and interact with objects and with others' people through our body. To properly perform actions, the representations of the dimension of body-parts (metric body representation, BR) and of the space surrounding the body (peripersonal space, PPS) need to be constantly updated. Previous evidence has shown that BR and PPS representation are highly flexible, being modulated by sensorimotor experiences, such as the active use of tools to reach objects in the far space. In this study, we investigate whether the observation of another person using a tool to interact with objects located in the far space is sufficient to influence the plasticity of BR and PPS representation in a similar way to active tool-use. With this aim, two groups of young healthy participants were asked to perform 20 min trainings based on the active use of a tool to retrieve far cubes (active tool-use) and on the first-person observation of an experimenter doing the same tool-use training (observational tool-use). Behavioural tasks adapted from literature were used to evaluate the effects of the active and observational tool-use on BR (body-landmarks localization task-group 1), and PPS (audio-tactile interaction task - group 2). Results show that after active tool-use, participants perceived the length of their arm as longer than at baseline, while no significant differences appear after observation. Similarly, significant modifications in PPS representation, with comparable multisensory facilitation on tactile responses due to near and far sounds, were seen only after active tool-use, while this did not occur after observation. Together these results suggest that a mere observational training could not be sufficient to significantly modulate BR or PPS. The dissociation found in the active and observational tool-use points out differences between action execution and action observation, by suggesting a fundamental role of the motor planning, the motor intention, and the related sensorimotor feedback in driving BR and PPS plasticity.
在日常生活中，我们通过身体与物体和他人不断地进行互动。为了正确地执行动作，身体部位的维度（度量身体表示，BR）和身体周围空间（peripersonal 空间，PPS）的表示需要不断更新。先前的证据表明，BR 和 PPS 表示具有高度的灵活性，会受到运动感觉经验的调节，例如主动使用工具来够到远处的物体。在这项研究中，我们研究了观察另一个人使用工具与位于远处的物体相互作用是否足以以类似于主动使用工具的方式影响 BR 和 PPS 表示的可塑性。为此，两组年轻健康的参与者被要求进行 20 分钟的训练，训练内容基于主动使用工具够取远处的方块（主动使用工具）和观察者进行相同的工具使用训练（观察性工具使用）。我们使用了从文献中改编的行为任务来评估主动和观察性工具使用对 BR（身体地标定位任务-第 1 组）和 PPS（音频触觉交互任务-第 2 组）的影响。结果表明，在主动使用工具后，参与者感知到自己手臂的长度比基线时更长，而观察后则没有明显差异。同样，仅在主动使用工具后，才会观察到 PPS 表示的显著变化，由于近距和远距声音，触觉反应的多感觉促进作用相当，而在观察后则不会出现这种情况。这些结果表明，仅观察性训练可能不足以显著调节 BR 或 PPS。在主动和观察性工具使用中发现的差异表明，动作执行和动作观察之间存在差异，这表明运动计划、运动意图和相关的运动感觉反馈在驱动 BR 和 PPS 可塑性方面起着基本作用。
