Connectomic mapping of pharyngeal and gut sensory circuits in adult Drosophila

Feeding is regulated by both external sensory signals, such as taste, and internal sensory signals originating from the pharynx and gut. The recent completion of the Full Adult Fly Brain (FAFB) connectome provides an opportunity to comprehensively map these sensory pathways and their downstream circuits. While external gustatory receptor neurons have been relatively well characterized, internal pharyngeal and gut sensory neurons remain less understood. Here, we systematically identify pharyngeal and gut sensory axons in the FAFB connectome and classify them into distinct subtypes. Mapping their downstream circuits reveals the major brain regions targeted by these internal sensory neurons. Notably, a subset forms monosynaptic connections with motor neurons and endocrine cells, suggesting direct pathways through which internal sensory signals influence feeding-related motor and endocrine outputs. Together, our findings delineate pharyngeal and gut sensory circuits, providing a foundation for future studies of how internal sensory signals regulate feeding behavior and endocrine function.