The Crunchometer: A Low-Cost, Open-Source Acoustic Analysis of Feeding Microstructure.

Elucidating the neuronal circuits that govern appetite requires a detailed analysis of the microstructure of solid food consumption. A significant barrier in this field is that existing techniques for monitoring feeding are either prohibitively expensive, limiting their use, or lack the high temporal resolution necessary to align feeding events with neuronal activity. To overcome this, we developed the Crunchometer, a low-cost, open-source acoustic system that uses computational algorithms to create high-resolution feeding ethograms. We validated the system by monitoring feeding across different energy states (hunger/satiety) and by demonstrating that the anti-obesity drug semaglutide suppresses food intake and reduces preference for a high-fat diet. Crucially, the Crunchometer integrates seamlessly with in vivo neural recordings in freely behaving mice. By pairing our system with electrophysiology in the Lateral Hypothalamus (LH), we identified novel "meal-related" neurons that track entire meals rather than individual feeding bouts. Using calcium imaging, we further revealed that solid food consumption strongly modulates LH GABAergic neurons, but not glutamatergic neurons. We also found that distinct LH neuronal ensembles encode the consumption of solid food versus liquid sucrose. The Crunchometer is thus a powerful and accessible tool for precisely dissecting the neural correlates of naturalistic feeding behavior.