Observation of others' painful heat stimulation involves responses in the spinal cord.

Observing others' aversive experiences is central to know what is dangerous for ourselves. Hence, observation often elicits behavioral and physiological responses comparable to first-hand aversive experiences and engages overlapping brain activation. While brain activation to first-hand aversive experiences relies on connections to the spinal cord, it is unresolved whether merely observing aversive stimulation also involves responses in the spinal cord. Here, we show that observation of others receiving painful heat stimulation involves neural responses in the spinal cord, located in the same cervical segment as first-hand heat pain. However, while first-hand painful experiences are coded within dorsolateral regions of the spinal cord, observation of others' painful heat stimulation involves medial regions. Dorsolateral areas that process first-hand pain exhibit negative responses when observing pain in others. Our results suggest a distinct processing between self and others' pain in the spinal cord when integrating social information.