Danger in the dark! Localization of nociceptive stimuli in normally sighted and congenitally blind people

To defend our body against potential physical threats, it is crucial to identify which body part is being damaged, but also to locate the threatening stimulus in its surroundings. Therefore, the brain coordinates the representation of the body with that of external space. To this aim, somatosensory inputs are remapped from the somatotopic towards a spatiotopic representation. The development of this spatial remapping would mainly rely on early visual experience. To test this hypothesis, we compared the ability of normally sighted and congenitally blind individuals to localize nociceptive stimuli. Participants performed temporal order judgement tasks during which they had to discriminate the temporal order of two nociceptive stimuli, one applied on each hand, with either their hands uncrossed or crossed over the body midline. While congenitally blinds were not affected by the posture, the performance of the sighted decreased in the crossed as compared to the uncrossed condition. This indicates that nociceptive stimuli are automatically remapped into a spatiotopic representation (where are the hands?) that interferes with the somatotopic representation (which hand is stimulated first?), whereas congenitally blinds seemed to only rely on a somatotopic map. This suggests that the way we perceive nociceptive stimuli is shaped by visual experience