Empathy or Ownership? Evidence from Corticospinal Excitability Modulation during Pain Observation

Abstract

Recent studies show that motor responses similar to those present in one's own pain (freezing effect) occur as a result of observation of pain 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 over M1 were recorded from first dorsal interosseous muscle, whereas participants 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 MEP amplitude (a significantly greater MEP reduction in the "pain" compared with 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.

The Embodiment of Objects: Review, Analysis, and Future Directions

“…Finally, it is important to note the influence of perspective for embodiment although it is still a matter of discussion. On the one hand, some studies have suggested that the firstperson perspective is important for embodiment (Blanke and Metzinger, 2009), which seems to be confirmed in rubber hand experiments (Pavani et al, 2000;Kalckert and Ehrsson, 2012;Bucchioni et al, 2016) and full body virtual reality experiments (Petkova and Ehrsson, 2008;Slater et al, 2010;Petkova et al, 2011;Maselli and Slater, 2013). Also, researchers found with the use of a questionnaire (Tieri et al, 2015b), measuring skin conductance response (Tieri et al, 2015a), and electroencephalographic response (Pavone et al, 2016), that passively observing a virtual body in first-person perspective is sufficient for embodiment (Maselli and Slater, 2013;Tieri et al, 2015bTieri et al, , 2017.…”

Frequency-dependent changes in sensorimotor and pain affective systems induced by empathy for pain

“…This is the first study in which EEG and MEG modulations were evaluated under the condition that MEP suppression was confirmed. Because painful visual stimuli do not always induce M1 inhibition,21,22 it is important to evaluate EEG and MEG oscillations while MEP suppression is also observed. The results of this study add further evidence of sensorimotor and cognitive–affective representations of empathy for pain processing.…”

“…They have also shown that MEP suppression needs a “flesh and bone” stimulus, and not just pricking a hand 21. MEP suppression is also modulated by first-person or third-person perspective 22. Thus, our painful visual stimuli were chosen appropriately to suppress the corticospinal tract.…”

“…Thus, sensorimotor modulation by empathic pain may be dependent on “flesh and bone” painful stimuli. MEP suppression is also dependent on the first-person or third-person perspective 22. Therefore, it is important to consider whether MEPs are suppressed when evaluating the modulation of neural oscillations by empathic pain.…”

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

“…Electromyographic (EMG) activity was recorded (MP150, Biopac System, USA) from the right First Dorsal Interosseous muscle (FDI), using one pair of bipolar surface electrodes with the active electrode over the muscle belly and the reference electrode over the associated joint or tendon. Signal was amplified and digitalized with a sample rate of 10 kHz, filtered with a band‐pass (10–500 Hz) and a notch (50 Hz), according to the method used in previous studies (Bruno, Fossataro, Bolognini, et al., ; Bucchioni et al., ; Fossataro et al., ), and stored for off‐line analysis.…”