title: Proprioception Is Necessary for Body Schema Plasticity: Evidence from a Deafferented Patient.
abstract: The ability of using a large variety of tools is important in our daily life. Behind human tool-use abilities lays the brain capacity to incorporate tools into the body representation for action (Body Schema, BS), thought to rely mainly on proprioceptive information. Here, we tested whether tool incorporation is possible in absence of proprioception by studying a patient with right upper-limb deafferentation. We adopted a paradigm sensitive to changes of the BS and analyzed the kinematics of free-hand movements before and after tool-use, in three sessions over a period of 2 years. In the first session, before tool-use, the kinematics of the deafferented hand was disrupted. Similarly, the first movements with the tool (a mechanical grabber elongating the arm by ~40 cm) showed an abnormal profile that tended to normalize at the end of the session. Subsequent free-hand movements were also normalized. At session 2, 6 months later, the patient exhibited normal free-hand kinematic profiles, additionally showing changes in grasping kinematics after tool-use, but no sign of tool incorporation. A follow-up 2 years later, further confirmed the normalized kinematic profile but the absence of tool incorporation. This first description of tool-use in absence of proprioception shows the fundamental role of proprioception in the update of the BS. These results provide an important further step in understanding human motor control and have implications for future development of rehabilitation programs for patients with sensory deficits.
authors.affiliation: The Brain and Mind Institute, University of Western Ontario, London, ONCanada; ImpAct Team, Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, LyonFrance; University of Lyon, LyonFrance; Hospices Civils de Lyon, Hôpital Neurologique, Mouvement et Handicap and Neuro-immersion, LyonFrance.
authors.forename: Lucilla
authors.initials: L
authors.lastname: Cardinali
authors.affiliation: Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm Sweden.
authors.forename: Claudio
authors.initials: C
authors.lastname: Brozzoli
authors.affiliation: ImpAct Team, Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, LyonFrance; University of Lyon, LyonFrance; Hospices Civils de Lyon, Hôpital Neurologique, Mouvement et Handicap and Neuro-immersion, LyonFrance.
authors.forename: Jacques
authors.initials: J
authors.lastname: Luauté
authors.affiliation: Laboratoire Dynamique Du Langage, CNRS UMR 5596, Lyon France.
authors.forename: Alice C
authors.initials: AC
authors.lastname: Roy
authors.affiliation: ImpAct Team, Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, LyonFrance; University of Lyon, LyonFrance; Hospices Civils de Lyon, Hôpital Neurologique, Mouvement et Handicap and Neuro-immersion, LyonFrance.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Farnè
keywords: body schema; deafferentation; grasping; kinematic; tool-use