Shared neural mechanisms between imagined and perceived egocentric motion - A combined GVS and fMRI study

Research ReportShared neural mechanisms between imagined andperceived egocentric motioneA combined GVSand fMRI studyGianluca Macaudaa,*, Marius Moisab, Fred W. Masta, Christian C. Ruffb,Lars Michelsc,1and Bigna Lenggenhagerd,1aDepartment of Psychology, University of Bern, Bern, SwitzerlandbZurich Center for Neuroeconomics (ZNE), Department of Economics, University of Zurich, Zurich, SwitzerlandcDepartment for Neuroradiology, University Hospital Zurich, Zurich, SwitzerlanddDepartment of Psychology, University of Zurich, Zurich, Switzerlandarticle infoArticle history:Received 16 November 2018Reviewed 20 December 2018Revised 6 February 2019Accepted 2 April 2019Action editor Paolo BartolomeoPublished online 12 April 2019Keywords:Egocentric mental rotationGalvanic vestibular stimulationFunctional magnetic resonanceimagingabstractMany cognitive and social processes involve mental simulations of a change in perspective.Behavioral studies suggest that such egocentric mental rotations rely on brain areas thatare also involved in processing actual self-motion, thus depending on vestibular input. In acombined galvanic vestibular stimulation (GVS) and functional Magnetic Resonance Im-aging (fMRI) study, we investigated the brain areas that underlie both simulated changes inself-location and the processing of vestibular stimulation within the same individuals.Participants performed an egocentric mental rotation task, an object-based mental rotationtask, or a pure lateralization task during GVS or sham stimulation. At the neural level, weexpected an overlap between brain areas activated during vestibular processing andegocentric mental rotation (against object-based mental rotation) within area OP2 and thePosterior Insular Cortex (PIC), two core brain regions involved in vestibular processing. ThefMRI data showed a small overlap within area OP2 and a larger overlap within the PIC forboth egocentric mental rotation against object-based mental rotation and vestibular pro-cessing. GVS did not influence the ability to perform egocentric mental rotation. Our resultsprovide evidence for shared neural mechanisms underlying perceived and simulated self-motion. We conclude that mental rotation of one's body involves neural activity in the PICand area OP2, but the behavioral results also suggest that those mental simulations of one'sbody might be robust to modulatory input from vestibular stimulation