Shared neurocognitive mechanisms of attenuating self-touch and illusory self-touch

Despite the fact that any successful achievement of willed actions necessarily entails the sense of body ownership (the feeling of owning the moving body parts), it is still unclear how this happens. To address this issue at both behavioral and neural level, we capitalized on sensory attenuation phenomenon (a self-generated stimulus is perceived as less intense than an identical externally-generated stimulus). We compared the intensity of somatosensory stimuli produced by one's own intended movements and by movements of an embodied fake hand. Then, we investigated if in these two conditions sensory attenuation was equally affected by interfering with the activity of the Supplementary Motor Area (known to be related to motor intention and sensory attenuation) using single-pulse TMS. We showed that ownership of the fake hand triggered attenuation of somatosensory stimuli generated by its movements that was comparable to the attenuation of self-generated stimuli. Furthermore, disrupting the Supplementary Motor Area eliminated the sensory attenuation effect regardless of whether it was triggered by actual participant's movements or by illusory ownership. Our findings suggest that sensory attenuation triggered by body ownership relies, at least in part, on the activation of the same brain structures as sensory attenuation triggered by motor-related signals.