Abstract
Investigation of rodent drinking behavior has provided insight into drivers of thirst, circadian rhythms, anhedonia, and drug and ethanol consumption. Traditional methods of recording fluid intake involve weighing bottles, which is cumbersome and lacks temporal resolution. Several open-source devices have been designed to improve drink monitoring, particularly for two-bottle choice tasks. However, beam-break sensors lack the ability to detect individual licks for bout microstructure analysis. Thus, we designed LIQ HD (Lick Instance Quantifier Home cage Device) with the goal of using capacitive sensors to increase accuracy and analyze lick microstructure, building a device compatible with ventilated home cages, increasing scale with prolonged undisturbed recordings, and creating a design that is easy to build and use with an intuitive touchscreen graphical user interface. The system tracks two-bottle choice licking behavior in up to 18 rodent cages, or 36 single bottles, on a minute-to-minute timescale controlled by a single Arduino microcontroller. The data are logged to a single SD card, allowing for efficient downstream analysis. LIQ HD accuracy was validated with sucrose, quinine, and ethanol two-bottle choice tasks. The system measures preference over time and changes in bout microstructure, with undisturbed recordings tested up to 7 d. All designs and software are open-source to allow other researchers to build on the system and adapt LIQ HD to their animal home cages.
Footnotes
The authors declare no competing financial interests.
N.P. was supported by the National Institute on Alcohol Abuse and Alcoholism F30 Grant AA029599, the National Institute of General Medical Sciences T32 Grant GM007347, and the National Institute of Neurological Disorders and Stroke R01 Diversity Supplement Grant NS102306-04S1. R.R. was supported by the National Institute of Diabetes and Digestive and Kidney Diseases T32 Grant DK007563. M.A.D. was supported by the National Institute on Alcohol Abuse and Alcoholism F32 Grant AA029592 and National Institute of Neurological Disorders and Stroke and National Institute of Mental Health T32 Grants NS007491 and MH065215. The research was supported by the National Institute on Alcohol Abuse and Alcoholism R37 Grant AA019455.
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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