title: Self-Grounded Vision: Hand Ownership Modulates Visual Location through Cortical β and γ Oscillations.
abstract: Vision is known to be shaped by context, defined by environmental and bodily signals. In the Taylor illusion, the size of an afterimage projected on one's hand changes according to proprioceptive signals conveying hand position. Here, we assessed whether the Taylor illusion does not just depend on the physical hand position, but also on bodily self-consciousness as quantified through illusory hand ownership. Relying on the somatic rubber hand illusion, we manipulated hand ownership, such that participants embodied a rubber hand placed next to their own hand. We found that an afterimage projected on the participant's hand drifted depending on illusory ownership between the participants' two hands, showing an implication of self-representation during the Taylor illusion. Oscillatory power analysis of electroencephalographic signals showed that illusory hand ownership was stronger in participants with stronger α suppression over left sensorimotor cortex, whereas the Taylor illusion correlated with higher β/γ power over frontotemporal regions. Higher γ connectivity between left sensorimotor and inferior parietal cortex was also found during illusory hand ownership. These data show that afterimage drifts in the Taylor illusion do not only depend on the physical hand position but also on subjective ownership, which itself is based on the synchrony of somatosensory signals from the two hands. The effect of ownership on afterimage drifts is associated with β/γ power and γ connectivity between frontoparietal regions and the visual cortex. Together, our results suggest that visual percepts are not only influenced by bodily context but are self-grounded, mapped on a self-referential frame.
  
  
  
  Vision is influenced by the body: in the Taylor illusion, the size of an afterimage projected on one's hand changes according to tactile and proprioceptive signals conveying hand position. Here, we report a new phenomenon revealing that the perception of afterimages depends not only on bodily signals, but also on the sense of self. Relying on the rubber hand illusion, we manipulated hand ownership, so that participants embodied a rubber hand placed next to their own hand. We found that visual afterimages projected on the participant's hand drifted laterally, only when the rubber hand was embodied. Electroencephalography revealed spectral dissociations between somatic and visual effects, and higher γ connectivity along the dorsal visual pathways when the rubber hand was embodied.
authors.affiliation: Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland, nathanfaivre@gmail.com.|Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.|Centre d'Economie de la Sorbonne, CNRS UMR 8174, Paris 75647, France.
authors.forename: Nathan
authors.identifier: 0000-0001-6011-4921
authors.initials: N
authors.lastname: Faivre
authors.affiliation: Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.|Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dönz
authors.affiliation: NPsy-Laboratory VR, Department of Philosophy, Education and Psychology, University of Verona, Verona 37129, Italy, and.
authors.forename: Michele
authors.identifier: 0000-0003-0853-8975
authors.initials: M
authors.lastname: Scandola
authors.affiliation: Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.|Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.
authors.forename: Herberto
authors.initials: H
authors.lastname: Dhanis
authors.affiliation: Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.|Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.
authors.forename: Javier
authors.initials: J
authors.lastname: Bello Ruiz
authors.affiliation: Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.|Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.
authors.forename: Fosco
authors.initials: F
authors.lastname: Bernasconi
authors.affiliation: Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.|Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.
authors.forename: Roy
authors.initials: R
authors.lastname: Salomon
authors.affiliation: Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.|Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne 1202, Switzerland.|Department of Neurology, University Hospital, Geneva 1211, Switzerland.
authors.forename: Olaf
authors.initials: O
authors.lastname: Blanke
mesh_terms: D000360:Afterimage; D000513:Alpha Rhythm / Q000502:physiology; D001611:Beta Rhythm / Q000502:physiology*; D001828:Body Image; D004532:Ego; D004569:Electroencephalography; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D065818:Gamma Rhythm / Q000502:physiology*; D006225:Hand; D006801:Humans; D007088:Illusions; D008297:Male; D010296:Parietal Lobe / Q000502:physiology; D012649:Self Concept; D066191:Sensorimotor Cortex / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology; D014796:Visual Perception; D055815:Young Adult
keywords: EEG; Taylor illusion; afterimage; bodily self-consciousness; embodiment; rubber hand illusion