Bonifazi S, Farnè A, Rinaldesi L, Làdavas E
Istituto di Riabilitazione S. Stefano, Porto Potenza Picena, Macerata, Italy.
J Neuropsychol. 2007 Mar;1(1):101-14. doi: 10.1348/174866407x180846.
Several studies in humans and non-human primates have shown that tool-use can expand near peripersonal space (Farnè & Làdavas, 2000; Iriki, Tanaka, & Iwamura, 1996). In humans, the extension of the near peripersonal space is revealed by an increase in the severity of cross-modal extinction caused by visual stimulation at the distal edge of a rake after its use as a reaching tool. The crucial question addressed here concerns whether the dynamic re-sizing of the peri-hand space in humans constitutes a real spatial expansion of visual-tactile peri-hand area along the tool axis. Alternatively, it could constitute a shift of the integrative area from the hand towards the distal edge of the tool, or the formation of a novel visual-tactile integrative area at the same distal location (Holmes, Calvert, & Spence, 2004). We contrasted the alternative predictions made by these hypotheses in a group of RBD patients by probing, at different locations along the tool axis, the changes induced by tool-use on cross-modal extinction. By assessing the visual-tactile extinction near the hand, midway along the tool, and at the distal edge of the tool we found an increase in visual-tactile extinction after tool-use both at the middle and the distal location along the tool axis. In contrast, no change intervened at the hand proximity. These findings support the view that the tool-use dependent re-mapping of peri-hand space in humans consists of a continuous elongation of visual-tactile peri-hand area from the hand towards the tip of the tool.
多项针对人类和非人类灵长类动物的研究表明，工具使用能够扩展近身体周围空间（法尔内和拉达瓦斯，2000年；入来、田中及岩村，1996年）。在人类中，近身体周围空间的扩展表现为，将耙子用作够取工具后，耙子远端边缘的视觉刺激所引发的跨通道消退严重程度增加。这里要解决的关键问题是，人类手部周围空间的动态重新调整是否构成视觉触觉手部周围区域沿工具轴的真正空间扩展。或者，它可能构成整合区域从手部向工具远端边缘的转移，或者在同一远端位置形成一个新的视觉触觉整合区域（霍姆斯、卡尔弗特和斯彭斯，2004年）。我们通过在工具轴的不同位置探测工具使用对跨通道消退的影响，对比了这些假设对一组快速眼动睡眠行为障碍（RBD）患者所做的不同预测。通过评估手部附近、工具中部以及工具远端边缘的视觉触觉消退情况，我们发现工具使用后，在工具轴的中部和远端位置，视觉触觉消退都有所增加。相比之下，手部附近没有变化。这些发现支持了这样一种观点，即人类中依赖工具使用的手部周围空间重新映射包括视觉触觉手部周围区域从手部向工具尖端的持续延伸。
