Empathy or Ownership? Evidence from corticospinal modulation during pain observation

Recent studies show that motor responses similar to those present in one’s own pain (freezing effect) occur as a result of pain-observation in others. This finding has been interpreted as the physiological basis of empathy. Alternatively, it can represent the physiological counterpart of an embodiment phenomenon related to the sense of body-ownership. We compared the empathy and the ownership hypotheses by manipulating the perspective of the observed hand-model receiving pain so that it could be a first-person perspective, the one in which embodiment occurs, or a third person perspective, the one in which we usually perceive the others. Motor evoked potentials (MEPs) by TMS on M1 were recorded from FDI muscle, while subjects observed video-clips showing a) a needle penetrating or b) a Q-tip touching a hand-model, presented either in first-person or in third-person perspective. We found that a pain-specific inhibition of MEPs amplitude (a significantly greater MEPs reduction in the “pain” compared to the “touch” conditions) only pertains to the first-person perspective and it is related to the strength of the self-reported embodiment. We interpreted this corticospinal modulation according to an “affective” conception of body-ownership, suggesting that the body I feel as my own is the body I care more about.