Do we feel touch where it actually occurs, or where the brain believes the body to be?

The way we feel our body results from a delicate balance between sensory signals and the way the brain constructs the boundary between “self” and “other.” Touch, in particular, is one of the pillars of this bodily identity: it is through touch that we distinguish what belongs to our body from what is external to it. But does this relationship work only in one direction? If the brain believes that something external is part of the body, can that change the way we feel touch?

In a study led by Alberto Pisoni and Carlotta Fossataro, this question was explored using the Rubber Hand Illusion, which temporarily leads a person to feel a fake hand as if it were their own. After each illusory phase, participants received touches either on the fake hand (which they experienced as embodied) or on the real hand.

The results revealed a consistent pattern: when participants saw the fake hand being touched, they felt the touch as more intense, even without receiving any real tactile stimulation; and when the touch was actually applied to the real hand, they experienced it as less intense. This effect depended on how strongly the person felt that the fake hand truly belonged to their body. In other words, the more the fake hand was perceived as “mine,” the more the brain amplified the sensation of touch on that hand, and decreased it on the real hand. This reflects a top‑down mechanism, in which the brain “decides,” from higher‑level processes, where touch should be felt more strongly-adjusting perception as if turning a volume knob.

To understand the associated neural mechanism, the authors used TMS‑EEG focused on alpha‑band connectivity in the somatosensory cortex (S1), a key area for touch. They found that this connectivity increased for visual touch on the embodied hand and decreased for real touch on the actual hand. This means that the brain reorganizes its tactile network depending on what it considers to be part of the body.

Thus, the present study suggests that we do not feel only because we are touched; we feel because the brain decides what is “mine.” The sense of body ownership shapes tactile perception, influencing both what we feel and how the brain processes touch. This study was published in the scientific journal Proceedings of the National Academy of Sciences, in the article Body ownership gates tactile awareness by reshaping the somatosensory functional connectivity, as a part of research project 311/20 - How body ownership shapes tactile awareness: Inducing phantom sensations and measuring their electrophysiological correlates in immersive virtual reality, supported by the Bial Foundation.

ABSTRACT

We all likely agree that tactile experience contributes to the emergence of the feeling of ownership over one’s own body. Is the opposite true? We answered this question by testing whether and how the sense of body ownership gates our tactile experience. In two experiments, we exploited a well-known multisensory illusion (Rubber Hand Illusion) to induce participants to feel a fake hand as belonging to their body, while their own hand was left in a disembodiment state (illusory-phases). After each illusory phase, a tactile stimulus was delivered to either the fake (embodied) hand or the real (disembodied) hand (testing-phases). Experiment 1 shows that the illusory phase significantly modulates the subjective feeling of touch experienced in the testing-phase, increasing tactile sensations when participants observed the fake (embodied) hand being touched (visual-touch), and decreasing them when the real (disembodied) hand was touched (real-touch). Experiment 2 investigated, by using TMS-EEG, the neural mechanism supporting this diametrical modulation of subjective feeling of touch, focusing on alpha-band oscillatory networks as the neural correlate of somatosensory awareness. S1 alpha-band connectivity fully matches the behavioral results, significantly increasing in visual-touch and decreasing in real-touch. In both experiments, a greater embodiment experienced in the illusory-phase significantly predicted higher behavioral and neurofunctional responses to visual-touch and lower responses to real-touch in the testing-phase. Altogether, our findings demonstrate that the sense of body ownership exerts a top-down modulation on tactile awareness and may do so by increasing or decreasing the strength of the somatosensory network involved in tactile awareness.