A Capacitance-Based System for Measuring Licking Behaviour in Rodents With Sub-Second Precision

BACKGROUND: The ability to measure drinking behaviour in laboratory animals is fundamental for neuroscience and metabolic research. In particular, the analysis of lick microstructure is an important tool for studying ingestive behaviour, motivation, and food preference. To capture lick microstructure, sensors capable of detecting licks in animals with a time resolution of only a few milliseconds are required. METHODS: We designed a lick sensor that can be used with standard drinking bottles and does not require modifications to animal cages. It can be used in any experimental arena and with one or more drinking bottles simultaneously. Moreover, this lickometer reports lick events in real time and is thus suitable for driving additional laboratory hardware for real-time loop-control experiments. Our design is publicly available. RESULTS: To validate our lick sensor we measured licks in mice offered water or sucrose drinks. Our sensor captured the same features of licking behaviour that have been reported before for these conditions using alternative lick sensors. CONCLUSIONS: The lick sensor described here is reliable while being easy to build and less expensive than known alternatives. It also facilitates the integration of lick measurements with other laboratory instruments in real time. This sensor lowers the barrier to implementing lick-sensing instrumentation in the laboratory which will be of benefit for research in neuroscience and metabolism.