title: Anchoring the Self to the Body in Bilateral Vestibular Failure.
abstract: Recent findings suggest that vestibular information plays a significant role in anchoring the self to the body. Out-of-body experiences of neurological origin are frequently associated with vestibular sensations, and galvanic vestibular stimulation in healthy participants anchors the self to the body. Here, we provide the first objective measures of anchoring the self to the body in chronic bilateral vestibular failure (BVF). We compared 23 patients with idiopathic BVF to 23 healthy participants in a series of experiments addressing several aspects of visuo-spatial perspective taking and embodiment. In Experiment 1, participants were involved in a virtual "dot-counting task" from their own perspective or the perspective of a distant avatar, to measure implicit and explicit perspective taking, respectively. In both groups, response times increased similarly when the avatar's and participant's viewpoint differed, for both implicit and explicit perspective taking. In Experiment 2, participants named ambiguous letters (such as "b" or "q") traced on their forehead that could be perceived from an internal or external perspective. The frequency of perceiving ambiguous letters from an internal perspective was similar in both groups. In Experiment 3, participants completed a questionnaire measuring the experienced self/body and self/environment "closeness". Both groups reported a similar embodied experience. Altogether, our data show that idiopathic BVF does not change implicit and explicit perspective taking nor subjective anchoring of the self to the body. Our negative findings offer insight into the multisensory mechanisms of embodiment. Only acute peripheral vestibular disorders and neurological disorders in vestibular brain areas (characterized by strong multisensory conflicts) may evoke disembodied experiences.
authors.affiliation: Aix Marseille Univ, CNRS, LNIA, FR3C, Marseille, France.
authors.forename: Diane
authors.identifier: http://orcid.org/0000-0001-5710-9419
authors.initials: D
authors.lastname: Deroualle
authors.affiliation: IRON, Institut de Recherche en Oto-Neurologie, Paris, France.|Centre d'Explorations Fonctionnelles Oto-Neurologiques, Paris, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Toupet
authors.affiliation: IRON, Institut de Recherche en Oto-Neurologie, Paris, France.|Unité Troubles de l'Equilibre et Vertiges, CHU Brugmann, Bruxelles, Belgique.|Unité de Neuro-Ophtalmologie, CHU Erasme, Bruxelles, Belgique.|Clinique des Vertiges, Bruxelles, Belgique.
authors.forename: Christian
authors.initials: C
authors.lastname: van Nechel
authors.affiliation: IRON, Institut de Recherche en Oto-Neurologie, Paris, France.|Unité Troubles de l'Equilibre et Vertiges, CHU Brugmann, Bruxelles, Belgique.|Clinique des Vertiges, Bruxelles, Belgique.
authors.forename: Ulla
authors.initials: U
authors.lastname: Duquesne
authors.affiliation: IRON, Institut de Recherche en Oto-Neurologie, Paris, France.|Service ORL, Hôpital Lariboisière, Paris, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Hautefort
authors.affiliation: Aix Marseille Univ, CNRS, LNIA, FR3C, Marseille, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Lopez
mesh_terms: D000071699:Bilateral Vestibulopathy / Q000503:physiopathology*; D016022:Case-Control Studies; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D011434:Proprioception / Q000502:physiology*; D011597:Psychomotor Performance; D055698:Touch Perception; D014796:Visual Perception