Interoception broadly refers to awareness of one's internal milieu. Although the importance of the body-to-brain communication that underlies interoception is implicit, the vagal afferent signalling and corresponding brain circuits that shape perception of the viscera are not entirely clear. Here, we use mice to parse neural circuits subserving interoception of the heart and gut. We determine that vagal sensory neurons expressing the oxytocin receptor (Oxtr), referred to as NGOxtr, send projecti...