title: Decoding illusory self-location from activity in the human hippocampus.
abstract: Decades of research have demonstrated a role for the hippocampus in spatial navigation and episodic and spatial memory. However, empirical evidence linking hippocampal activity to the perceptual experience of being physically located at a particular place in the environment is lacking. In this study, we used a multisensory out-of-body illusion to perceptually 'teleport' six healthy participants between two different locations in the scanner room during high-resolution functional magnetic resonance imaging (fMRI). The participants were fitted with MRI-compatible head-mounted displays that changed their first-person visual perspective to that of a pair of cameras placed in one of two corners of the scanner room. To elicit the illusion of being physically located in this position, we delivered synchronous visuo-tactile stimulation in the form of an object moving toward the cameras coupled with touches applied to the participant's chest. Asynchronous visuo-tactile stimulation did not induce the illusion and served as a control condition. We found that illusory self-location could be successfully decoded from patterns of activity in the hippocampus in all of the participants in the synchronous (P < 0.05) but not in the asynchronous condition (P > 0.05). At the group-level, the decoding accuracy was significantly higher in the synchronous than in the asynchronous condition (P = 0.012). These findings associate hippocampal activity with the perceived location of the bodily self in space, which suggests that the human hippocampus is involved not only in spatial navigation and memory but also in the construction of our sense of bodily self-location.
authors.affiliation: Department of Neuroscience, Karolinska Institutet, Stockholm Sweden.
authors.forename: Arvid
authors.initials: A
authors.lastname: Guterstam
authors.affiliation: Department of Neuroscience, Karolinska Institutet, Stockholm Sweden ; Department of Clinical and Experimental Medicine, Linköping University, Linköping Sweden.
authors.forename: Malin
authors.initials: M
authors.lastname: Björnsdotter
authors.affiliation: Department of Neuroscience, Karolinska Institutet, Stockholm Sweden ; Basque Center on Cognition, Brain and Language, Donostia Spain.
authors.forename: Loretxu
authors.initials: L
authors.lastname: Bergouignan
authors.affiliation: Department of Neuroscience, Karolinska Institutet, Stockholm Sweden ; Division of the Humanities and Social Sciences, California Institute of Technology, Pasadena, CA USA.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gentile
authors.affiliation: Department of Medical Physics, Karolinska University Hospital Huddinge, Stockholm Sweden.
authors.forename: Tie-Qiang
authors.initials: TQ
authors.lastname: Li
authors.affiliation: Department of Neuroscience, Karolinska Institutet, Stockholm Sweden.
authors.forename: H Henrik
authors.initials: HH
authors.lastname: Ehrsson
keywords: body perception; multisensory integration; perceptual illusion; self-consciousness; self-location