Poster D96, Monday, March 26, 8:00-10:00 am, Exhibit Hall C
Rubber Hand Illusion enhancement induced by motor cortex inhibition
Carlotta Fossataro1, Valentina Bruno1, Serena Giurgola2, Nadia Bolognini3,4, Francesca Garbarini1; 1SAMBA – SpAtial, Motor & Bodily Awareness – Research Group, Psychology Department, University of Turin, Turin, Italy, 2Department of Medicine and Surgery, University of Milano-Bicocca, Milan Italy, 3Department of Psychology & NeuroMI – Milan Center for Neuroscience, University of Milano-Bicocca, Milano, Italy, 4Neuropsychological Laboratory, IRCCS, Istituto Auxologico Italiano, Milano, Italy
A recent study showed that, while the subjects had been induced by the rubber hand illusion (RHI) to perceive a fake hand as part of their own body, their primary motor cortex (M1) excitability was temporarily decreased, so that they were less ready to move their real hand. Since an illusory body ownership triggers inhibitory effects on M1, here we aimed at investigating whether and to what extent modulating the excitability of M1 may affect the strength of the illusion. In the Main Experiment, off-line, sham-controlled, low-frequency (1 Hz) repetitive (r)TMS was applied over the left M1; the strength of the illusory experience was assessed by administering the RHI to the hand contralateral to the stimulated M1. In the Control Experiment, the RHI was performed in the hand ipsilateral to the inhibited M1. Results showed that 1-Hz rTMS over M1 significantly enhanced the illusory experience, as proved by a significant increase of both subjective (Embodiment/Disembodiment Questionnaires) and objective (Proprioceptive Drift) RHI measures as compared to Sham (Main Experiment). Moreover, the effect was specific for the hemisphere controlling the hand exposed to the illusion. These results provide evidence that, when the subjects are less ready to move their own body (as following M1-inhibition by rTMS), their sense of body-ownership is attenuated and they are more prone to incorporate an alien limb.
Topic Area: PERCEPTION & ACTION: Multisensory