Sensing vs. seeing: body experience rather than mere body observation is linked to efficiency of descending pain modulation.

Looking at one’s own body has been shown to exert analgesic effects on experimental pain stimulation. This study investigated the potential involvement of descending pain modulation and the role of body experience in this phenomenon. Non-clinical participants completed four experimental conditions with either a glass or mirror partition placed sagittally between their hands, which were either visible or covered with wooden boxes. This allowed participants to view either their left hand or the reflection of their right hand (each visible or covered), while they underwent a conditioned pain modulation (CPM) protocol with the test stimulus applied to their left hand. Disembodiment experiences regarding the left hand were additionally recorded using a questionnaire. Looking at the mirrored right hand significantly induced disembodiment experiences of the hidden left hand, even in the absence of explicit multisensory conflict. Across all conditions, significant CPM responses were observed. Although CPM responses were not modulated by mere vision of the left hand, their magnitude was significantly negatively correlated with disembodiment ratings. These results suggest that states of body experience modulate nociceptive processing through descending pathways. The findings are discussed within a body salience framework.