Losing my hand. Body ownership attenuation after virtual lesion of the primary motor cortex

A fundamental component of the self‐awareness is the sensation that we are acting with our own body. Thus, a coherent sense of self implies the existence of a tight link between the sense of body ownership and the motor system. Here, we investigated this issue by taking advantage of a well‐known exp...

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Published inThe European journal of neuroscience Vol. 48; no. 6; pp. 2272 - 2287
Main Authors Fossataro, Carlotta, Bruno, Valentina, Giurgola, Serena, Bolognini, Nadia, Garbarini, Francesca
Format Journal Article
LanguageEnglish
Published France Wiley Subscription Services, Inc 01.09.2018
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ISSN0953-816X
1460-9568
1460-9568
DOI10.1111/ejn.14116

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Summary:A fundamental component of the self‐awareness is the sensation that we are acting with our own body. Thus, a coherent sense of self implies the existence of a tight link between the sense of body ownership and the motor system. Here, we investigated this issue by taking advantage of a well‐known experimental manipulation of body ownership, i.e., the rubber hand illusion (RHI), during which the subjects perceive a fake hand as part of their own body. To test the effect of the motor system down‐regulation on the RHI susceptibility, we designed a sham‐controlled study, where the primary motor cortex (M1) excitability was modulated by off‐line low‐frequency repetitive transcranial magnetic stimulation (rTMS). After rTMS (real or sham), subjects underwent the RHI either on the right hand, contralateral to the inhibited hemisphere (Experiment 1), or on the left hand, ipsilateral to the inhibited hemisphere (Experiment 2). Only in Experiment 1, the procedure strengthened the illusory experience, as proved by a significant increase, in rTMS compared to Sham, of both subjective (Embodiment/Disembodiment Questionnaires) and objective (Proprioceptive Drift) RHI measures. This evidence demonstrates that, when the M1 activity is down‐regulated, the sense of body ownership is attenuated and the subjects become more prone to incorporate an alien body part. This, in turn, supports the existence of a mutual interaction between the sense of body ownership and the motor system, shedding new light on the construction of a coherent sense of self as an acting body. A mutual relationship between the sense of body ownership and the motor system exists. As demonstrated by della Gatta et al. (), an experimental manipulation of the sense of body ownership, by means of the RHI, modulates the motor cortex excitability (red arrow). As newly demonstrated by the present study, an experimental manipulation of the motor cortex excitability, by means of 1 Hz rTMS, modulates the strength of the RHI susceptibility (green arrow).
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ISSN:0953-816X
1460-9568
1460-9568
DOI:10.1111/ejn.14116