title: Neurological and robot-controlled induction of an apparition.
abstract: Tales of ghosts, wraiths, and other apparitions have been reported in virtually all cultures. The strange sensation that somebody is nearby when no one is actually present and cannot be seen (feeling of a presence, FoP) is a fascinating feat of the human mind, and this apparition is often covered in the literature of divinity, occultism, and fiction. Although it is described by neurological and psychiatric patients and healthy individuals in different situations, it is not yet understood how the phenomenon is triggered by the brain. Here, we performed lesion analysis in neurological FoP patients, supported by an analysis of associated neurological deficits. Our data show that the FoP is an illusory own-body perception with well-defined characteristics that is associated with sensorimotor loss and caused by lesions in three distinct brain regions: temporoparietal, insular, and especially frontoparietal cortex. Based on these data and recent experimental advances of multisensory own-body illusions, we designed a master-slave robotic system that generated specific sensorimotor conflicts and enabled us to induce the FoP and related illusory own-body perceptions experimentally in normal participants. These data show that the illusion of feeling another person nearby is caused by misperceiving the source and identity of sensorimotor (tactile, proprioceptive, and motor) signals of one's own body. Our findings reveal the neural mechanisms of the FoP, highlight the subtle balance of brain mechanisms that generate the experience of "self" and "other," and advance the understanding of the brain mechanisms responsible for hallucinations in schizophrenia.
authors.affiliation: Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland; Department of Neurology, University Hospital of Geneva, Rue Micheli-du-Crest 24, 1205 Geneva, Switzerland; Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland. Electronic address: olaf.blanke@epfl.ch.
authors.forename: Olaf
authors.initials: O
authors.lastname: Blanke
authors.affiliation: Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland; Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland.
authors.forename: Polona
authors.initials: P
authors.lastname: Pozeg
authors.affiliation: Advanced Mechatronic Laboratory, Department of Precision Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hara
authors.affiliation: Department of Neurology, University Hospital of Geneva, Rue Micheli-du-Crest 24, 1205 Geneva, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Heydrich
authors.affiliation: Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland; Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Serino
authors.affiliation: Advanced Mechatronic Laboratory, Department of Precision Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Yamamoto
authors.affiliation: Advanced Mechatronic Laboratory, Department of Precision Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo, Japan.
authors.forename: Toshiro
authors.initials: T
authors.lastname: Higuchi
authors.affiliation: Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland; Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland.
authors.forename: Roy
authors.initials: R
authors.lastname: Salomon
authors.affiliation: Department of Neurology, University Hospital of Geneva, Rue Micheli-du-Crest 24, 1205 Geneva, Switzerland.
authors.forename: Margitta
authors.initials: M
authors.lastname: Seeck
authors.affiliation: Department of Neurology, University Hospital of Geneva, Rue Micheli-du-Crest 24, 1205 Geneva, Switzerland.
authors.forename: Theodor
authors.initials: T
authors.lastname: Landis
authors.affiliation: Department of Neurology, Hadassah Hebrew University Medical Center, P.O. Box 12000, 91120 Jerusalem, Israel.
authors.forename: Shahar
authors.initials: S
authors.lastname: Arzy
authors.affiliation: Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland; Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland.
authors.forename: Bruno
authors.initials: B
authors.lastname: Herbelin
authors.affiliation: Laboratory of Robotic Systems, School of Engineering, Ecole Polytechnique Fédérale de Lausanne, Station 17, 1015 Lausanne, Switzerland.
authors.forename: Hannes
authors.initials: H
authors.lastname: Bleuler
authors.affiliation: Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland; Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland; Laboratory of Robotic Systems, School of Engineering, Ecole Polytechnique Fédérale de Lausanne, Station 17, 1015 Lausanne, Switzerland.
authors.forename: Giulio
authors.initials: G
authors.lastname: Rognini
mesh_terms: D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology; D006801:Humans; D007088:Illusions / Q000523:psychology*; D012371:Robotics