Somatosensory-guided tool use modifies arm representation for action

Marie Martel (1) , Lucilla Cardinali , Giorgia Bertonati (1, 2, 3) , Christophe Jouffrais (4, 5) , Livio Finos (6) , Alessandro Farnè (2, 3, 7, 8) , Alice Roy (1, 3)

1 DDL - Dynamique Du Langage
2 CRNL - Centre de recherche en neurosciences de Lyon - Lyon Neuroscience Research Center
3 CIMEC - Center for Mind/Brain Sciences
4 IPAL - Image & Pervasive Access Lab
5 IRIT-ELIPSE - Etude de L’Interaction Personne SystèmE
6 Unipd - Università degli Studi di Padova = University of Padua
7 Plate-forme Mouvement et handicap [Hôpital Henry Gabrielle - Lyon]
8 The Neurodis Fondation

Tool-use changes both peripersonal space and body representations, with several effects being nowadays termed tool embodiment. Since somatosensation was typically accompanied by vision in most previous tool use studies, whether somatosensation alone is sufficient for tool embodiment remains unknown. Here we address this question via a task assessing arm length representation at an implicit level. Namely, we compared movement's kinematics in blindfolded healthy participants when grasping an object before and after tool-use. Results showed longer latencies and smaller peaks in the arm transport component after tool-use, consistent with an increased length of arm representation. No changes were found in the hand grip component and correlations revealed similar kinematic signatures in naturally long-armed participants. Kinematics changes did not interact with target object position, further corroborating the finding that somatosensory-guided tool use may increase the represented size of the participants' arm. Control experiments ruled out alternative interpretations based upon altered hand position sense. In addition, our findings indicate that tool-use effects are specific for the implicit level of arm representation, as no effect was observed on the explicit estimate of the forearm length. These findings demonstrate for the first time that somatosensation is sufficient for incorporating a tool that has never been seen, nor used before.

Mots clés: Somatosensation

Domaines: Bio-informatique [q-bio.QM]

Marie Martel, Lucilla Cardinali, Giorgia Bertonati, Christophe Jouffrais, Livio Finos, et al.. Somatosensory-guided tool use modifies arm representation for action. Scientific Reports, 2019, 9 (5517), pp.1-14. ⟨10.1038/s41598-019-41928-1⟩. ⟨hal-02382718⟩