Empathic neural reactivity to noxious stimuli delivered to body parts and non-corporeal objects.

Neuroimaging studies report that the experience of observing or imagining the pain of others is mapped on a set of neural structures that largely overlap those called into play during the personal experience of pain (the so-called pain matrix). Empathy for pain is a multifaceted process that may be triggered by higher-order variables (such as imagination of others' suffering) or by the direct vision of painful situations. Most functional magnetic resonance imaging studies indicate that the empathic mapping of others' pain may rely on the affective and not on the sensorimotor division of the pain matrix. However, as empathy for pain is a complex, multifarious process, it is possible that different brain regions, even beyond the classic pain matrix, may be called into action in different circumstances. By using functional magnetic resonance imaging we explored the neural activity induced by needles deeply penetrating a hand or a non-corporeal object. We found that observation of pain in others brought about activation in the middle cingulate, left premotor and left and right supramarginal regions. This pattern of neural activity indicates that the direct vision of strong painful stimuli delivered to others activates neural regions in the onlooker's brain specifically concerned with the resonant, interindividual sharing of basic sensorimotor reactivity to pain. We also found that bilateral posterior parietal and temporo-occipital regions were activated during observation of painful stimuli delivered to the body of others as well as to non-body stimuli. Therefore, our study expands current knowledge on the neural reactivity to potentially dangerous stimuli delivered in the peripersonal space.