Body ownership determines the attenuation of self-generated tactile sensations

Significance

When we touch one hand with the other, the touch feels less intense than identical touches generated by another person or robot. This is because our brain predicts the contact between our hands and attenuates the expected sensation. Here, we describe how the attenuation of self-touch depends on the experienced ownership of the touching hand. We found that illusory self-touch with a rubber hand that feels like one’s own is attenuated. We also found the reverse: The attenuation of real self-touch is reduced when the rubber hand that feels like one’s own is far from the receiving hand. These findings are important because they demonstrate that sensory predictions and sensory attenuation depend on the sense of ownership of the body.

Abstract

Self-perception depends on the brain’s abilities to differentiate our body from the environment and to distinguish between the sensations generated as a consequence of voluntary movement and those arising from events in the external world. The first process refers to the sense of ownership of our body and relies on the dynamic integration of multisensory (afferent) signals. The second process depends on internal forward models that use (efferent) information from our motor commands to predict and attenuate the sensory consequences of our movements. However, the relationship between body ownership and sensory attenuation driven by the forward models remains unknown. To address this issue, we combined the rubber hand illusion, which allows experimental manipulation of body ownership, and the force-matching paradigm, which allows psychophysical quantification of somatosensory attenuation. We found that a rubber right hand pressing on the left index finger produced somatosensory attenuation but only when the model hand felt like one’s own (illusory self-touch); reversely, the attenuation that was expected to occur during actual self-touch with the real hands was reduced when the participants simultaneously experienced ownership of a rubber right hand that was placed at a distance from their left hand. These results demonstrate that the sense of body ownership determines somatosensory attenuation. From a theoretical perspective, our results are important because they suggest that body ownership updates the internal representation of body state that provides the input to the forward model generating sensory predictions during voluntary action.