The role played by tool-use and tool-length on the Plastic Elongation of peri-hand space: a single case study

Abstract

Consistent with neurophysiological findings showing expansion of the visual RF of visuo-tactile neurons along the rake used by monkeys to retrieve out-of-hand-reach objects (Iriki, Tanaka, & Iwamura, 1996), we have previously shown that also in humans the use of a tool can increase the spatial extent of the representation of peri-hand space, as revealed by an increase in the severity of cross-modal extinction after tool use (Farnè & Làdavas, 2000). Here we further explored the characteristics of such a transient elongation of the multisensory peri-hand space representation in a patient with visual-tactile extinction. By investigating the variation of cross-modal extinction following different types of tool-related experience, we found that passive exposure to the tool is not sufficient per se to induce peri-hand space extension, which instead requires that the tool is used. This increase of peri-hand extension might be related to the physical length of the tool.

Acknowledgments

We wish to thank LE for his willingness to collaborate. We thank Francesca Frassinetti for CT scan reading and lesion reconstruction. This work was supported by grants from MUIR and RFO.