Proprioceptive drift in the rubber hand illusion is intensified following 1 Hz TMS of the left EBA.

Andrew Wold,Jakub Limanowski,Henrik Walter,Felix Blankenburg

doi:10.3389/fnhum.2014.00390

Abstract

The rubber hand illusion (RHI) is a paradigm used to induce an illusory feeling of owning a dummy hand through congruent multisensory stimulation. Thus, it can grant insights into how our brain represents our body as our own. Recent research has demonstrated an involvement of the extrastriate body area (EBA), an area of the brain that is typically implicated in the perception of non-face body parts, in illusory body ownership. In this experiment, we sought causal evidence for the involvement of the EBA in the RHI. Sixteen participants took part in a sham controlled, 1 Hz repetitive transcranial magnetic stimulation (rTMS) experiment. Participants received (RHI condition) or asynchronous (control) stroking and were asked to report the perceived location of their real hand, as well as the intensity and the temporal onset of experienced ownership of the dummy hand. Following rTMS of the left EBA, participants misjudged their real hand’s location significantly more toward the dummy hand during the RHI than after sham stimulation. This difference in “proprioceptive drift” provides the first causal evidence that the EBA is involved in the RHI and subsequently in body representation and further supports the view that the EBA is necessary for multimodal integration.

Highlights

The rubber hand illusion (RHI) is a well-established paradigm to manipulate the sense of body ownership in healthy individuals (Botvinick and Cohen, 1998)
Following repetitive transcranial magnetic stimulation (rTMS) of the left extrastriate body area (EBA), participants misjudged their real hand’s location significantly more toward the dummy hand during the RHI than after sham stimulation. This difference in “proprioceptive drift” provides the first causal evidence that the EBA is involved in the RHI and subsequently in body representation and further supports the view that the EBA is necessary for multimodal integration
Based on our assumption that rTMS stimulation would produce an effect compared to sham stimulation during synchronous stroking but not asynchronous stroking, we compared proprioceptive drift in the post-stimulation session using post hoc paired t-tests, which revealed a significantly (p < 0.025) stronger effect of rTMS versus sham stimulation on proprioceptive drift during synchronous stroking [t(15) = 2.578, p = 0.021], but not during asynchronous stroking [t(15) = 0.161, p = 0.876]

Summary

Introduction

The rubber hand illusion (RHI) is a well-established paradigm to manipulate the sense of body ownership in healthy individuals (Botvinick and Cohen, 1998). The EBA is an occipito-temporal visual region that has gained considerable attention in recent literature because of its selective, strong response to non-face body parts (Downing et al, 2001; Peelen and Downing, 2007; Downing and Peelen, 2011) and contribution to explicit representations of identity (Urgesi et al, 2007), body configurations (Pitcher et al, 2009), and goal-directed actions (Wiggett and Downing, 2011) Along these lines, a recent fMRI study by Limanowski et al (2014) demonstrated an involvement of the EBA in illusory body ownership. The involvement of the EBA in the RHI provides support for previous speculations about a role of this region in the representation of one’s body (Costantini et al, 2011; Apps and Tsakiris, 2014)

Methods

Results

Conclusion