Farnè, A. 1, 2 , Cardinali, L. 1, 2 , Brozzoli, C. 3 & Roy, A. C. 4
1 INSERM U1028, CNRS UMR 5292, Lyon Neuroscience Research Centre, ImpAct Team, F-69500 Lyon, France
2 University Claude Bernard Lyon I, F-69000 Lyon, France
3 Department of Neuroscience, Brain, Body & Self lab, Karolinska Institut, SE-17177 Stockholm, Sweden
4 CNRS UMR 5230 Laboratoire sur le Langage le Cerveau et la Cognition, Lyon Neuroscience Centre, F-69500 Bron, France
Along the evolutionary history, humans have reached a high level of sophistication in the way they interact with the environment. We are able to modify, adapt and shape the world around us according to our needs. One important step in this process has been the introduction of tools, enabling humans to go beyond the boundaries of their physical possibilities. Behind the complex phenomenon of phylogenetic development of tool-use, we will focus some “low-level” aspects of cognition that highlight how tool-use plays a causal role in shaping both spatial and bodily representations. Indeed, updating representations of the body and its action-space is essential for efficient motor control during development and skilful tool-use in the adult life. The almost one-century-old hypothesis that tool-use induces plastic changes resulting in the tool being incorporated in the body representation is widely accepted, and intuitive enough to become a popular notion. Here, we will critically review the evidence supporting this hypothesis on the basis of the effects of tool-use on multisensory coding of peripersonal space, as documented in the normal and pathological brain. Recent findings and ongoing work from our laboratory will be presented and discussed as evidence supporting the incorporation of a tool in the body representation. In particular, we will present several experiments that reveal the effects of tool-use both on the kinematics of hand movements and the localisation of somatosensory stimuli on the body surface, as well as the conditions that are necessary for these effects to be manifest. These findings speak in favour of genuine, tooluse-dependent plasticity of the body representation for the control of action.