Abstract
Measuring ingestive behavior of liquids in rodents is commonly used in studies of reward, metabolism and circadian biology. Common approaches for measuring liquid intake in real time include computer-tethered lickometers, or video-based systems. Additionally, liquids can be measured or weighed to determine the amount consumed without real-time sensing. Here, we built a photobeam-based sipper device that has the following advantages over traditional methods: 1) it is battery powered and fits in vivarium caging to allow home-cage measurements; 2) it quantifies intake of two different liquids simultaneously for preference studies 3) it is low-cost and easily constructed, enabling high-throughput experiments; 4) it is open-source so others can modify it to fit their experimental needs. We validated the performance of this device in three experiments. First, we calibrated our device using time lapse video-based measurements of liquid intake and correlated sipper interactions with liquid intake. Second, we used the sipper device to measure preference for water vs. chocolate milk, demonstrating its utility for two-bottle choice tasks. Third, we integrated the device with fiber photometry, establishing its utility for measuring neural activity in studies of ingestive behavior. This device requires no special equipment or caging, is small, battery powered, and wireless, allowing it to be placed directly in rodent home cages. The total cost of fabrication is less than $100, and all design files and code are open-source. Together, these factors greatly increase scalability and utility for a variety of behavioral neuroscience applications.
Impact Statement Current methods for measuring liquid consumption in rodents typically require specialized equipment that is tethered to an in-room computer. This makes portability and scalability challenging. We present a device that is small, battery powered, and wireless, allowing it to be placed directly in rodent home cages. Moreover, the total cost of fabrication is less than $100 and the design is open-source. Together, these factors greatly increase scalability, as the devices do not require dedicated experimental space or caging. The battery lasts approximately 2 weeks, enabling studies of long-term intake or circadian biology.
Footnotes
The authors report no conflict of interest.
Research was supported by internal funds Washington University in St. Louis (AVK, MCC), Brain and Behavior Research Foundation (NARSAD young investigator grant #27461 to AVK, #27197 to MCC), NIH NIDA CEBRA (R21-DA047127), Whitehall Foundation Grant (#2017-12-54) and Rita Allen Scholar Award in Pain to MCC.
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
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