Brainstem sensing of multiple body signals during food consumption.

The peripheral neural pathways that relay oral and post-ingestive chemo- and mechanosensory signals to the brain during food consumption are increasingly well understood. Far less is known about how these and other body signals are integrated and organized in the brainstem lateral parabrachial nucleus (LPBN), a key interoceptive sensory hub. We established methods for dense calcium imaging of 100s of neurons from mouse LPBN. Food consumption drove a seconds-long wave of activity across LPBN, with dynamics mirroring the movement of food through the upper gastrointestinal tract as observed using X-ray videofluoroscopy. By imaging the same neurons across days, we found that spatially clustered subsets of neurons encoded oral signals, stomach filling, visceral malaise, arousal, and/or body movement. Moreover, only certain subsets were modulated by cortical input. Together, these experiments establish a platform for understanding how peripheral and central interoceptive signals are integrated in the brainstem to guide behavior.