EXPLORING THE ROLE OF TRANSCRANIAL MAGNETIC STIMULATION ON VIRTUAL PROSTHESES EMBODIMENT

Aims: This study investigates whether transcranial magnetic stimulation (TMS) can enhance prosthesis embodiment, defined as the subjective experience of control and agency over an artificial limb. Methods: Six able-bodied participants and two subjects with limb loss were recruited and asked to control a virtual prosthetic arm using myoelectric signals. The experimental protocol included one training session and pre-/post- training assessments. During the training session, TMS was delivered over the Superior and Inferior Parietal Lobules when contact between the virtual prosthesis and a virtual object occurred, to perturb a pre-existing grasping plan. One additional testing session was performed with simultaneous delivery of TMS as control. Both task performance and embodiment-related metrics were evaluated. Embodiment was assessed using standardized subjective questionnaires, and the Locus of Attention Index (LAI), that quantifies the visual attentional ratio between task and prosthesis areas. Results: While subjective questionnaires do not highlight changes in embodiment, the LAI has shown a significant shift of attention from prosthesis to task in the post-training session (following TMS-assisted training), but not in the final testing where TMS was delivered simultaneously. Conclusions: Performing training with TMS suggests an enhanced embodiment, showing promise for therapeutic applications targeting embodiment of virtual limbs. Further studies will extend protocol and subject cohort to clarify potential long-term impact on motor performance.