Giuseppe Granata, David Guiraud, Andrea Serino, Giulio Rognini, Francesco Maria Petrini, Olaf Blanke, Robin Mange, Marco Solcà, Edoardo D'Anna, Giacomo Valle, Giovanni Di Pino, Ivo Strauss, Javier Bello-Ruiz, Paolo Maria Rossini, David Andreu, Bruno Herbelin, Silvestro Micera, Riccardo Di Iorio, Thomas Stieglitz, Stanisa Raspopovic, Center for Neuroprosthetics [Geneva] (CNP), Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Cognitive Neuroscience (LNCO), School of Engineering STI [Lausanne], Department of Health Sciences and Technology [ETH Zürich] (D-HEST), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Scuola Universitaria Superiore Sant'Anna [Pisa] (SSSUP), Università cattolica del Sacro Cuore [Roma] (Unicatt), Biomedical Robotics and Biomicrosystems Lab - UCBM, Università Campus Bio-Medico di Roma / University Campus Bio-Medico of Rome ( UCBM), Control of Artificial Movement and Intuitive Neuroprosthesis (CAMIN), Laboratoire d'Informatique de Robotique et de Microélectronique de Montpellier (LIRMM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Inria Sophia Antipolis - Méditerranée (CRISAM), Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Department of Microsystems Engineering [Freiburg] (IMTEK), University of Freiburg [Freiburg], Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS San Raffaele Pisana), Università cattolica del Sacro Cuore = Catholic University of the Sacred Heart [Roma] (Unicatt), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Inria Sophia Antipolis - Méditerranée (CRISAM)
A major goal of neuroprosthetics is to design artificial limbs that are experienced (‘embodied’) like real limbs. However, despite important technological advances, this goal has not been reached and prosthesis embodiment is still very limited. Differently from our physical body, current bionic limbs do not provide the continuous multisensory feedback required for a limb to be experienced as one’s own. Here, we present a novel neuroprosthetic approach that combines peripheral neurotactile stimulation—inducing tactile sensation on the missing limb—and immersive digital technology—providing visual illumination of the prosthetic hand. We tested whether coherent multisensory visuo-tactile neural stimulation (VTNS)1 induced higher prosthesis embodiment and reduced the distorted perception of the phantom limb (telescoping, ie, the phantom limb is perceived as shorter than the intact limb). Patient 1 and patient 2 are transradial left forearm chronic amputees, who suffered upper limb telescoping. Patients were implanted with transverse intrafascicular multichannel electrodes (TIMEs), which induced the sensation of a vibration in a circumscribed skin region of the finger 2 via medial nerve stimulation in patient 1 (online supplementary figure 1A) and in a skin region of finger 5 via ulnar nerve stimulation in patient 2 (online supplementary figure 1B and material 1). Neurotactile stimulation2 was coupled with automatised visual illumination of a skin region on the patient’s prosthetic hand that corresponded to the somatotopic location of touch sensations experienced on the phantom hand (VTNS; online supplementary video 1, online supplementary figure 1, online supplementary material 1). VTNS was administered in two conditions, either with synchronous visual and neurotactile stimulation or in a control condition of asynchronous stimulation (1.5–2.5s delay). ### Supplementary data [jnnp-2018-318570-supp1.pdf] ### Supplementary video [jnnp-2018-318570-supp1.mp4] Prosthesis embodiment was measured via a questionnaire, whereas changes in phantom limb perception were tested via a body landmark task where patients indicated the perceived position of different parts of the phantom limb …