Decoding illusory self-location from activity in the human hippocampus
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.
© 2015 Guterstam, Björnsdotter, Bergouignan, Gentile, Li and Ehrsson. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Received: 21 April 2015; Accepted: 03 July 2015; Published: 15 July 2015. The authors would like to thank John O'Keefe, Anthony Wagner, and Lars Nyberg for valuable comments on a previous version of the manuscript. This research was made possible by funding from the European Research Council, the Swedish Foundation for Strategic Research, the Swedish Research Council, the McDonnell Foundation, Söderbergska Stiftelsen, the Wenner-Gren Foundation (MB and LB) and the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement PIOF-GA-2012-302896 (MB).
Published - fnhum-09-00412.pdf