LIQ HD (Lick Instance Quantifier Home Cage Device): An Open-Source Tool for Recording Undisturbed Two-Bottle Drinking Behavior in a Home Cage Environment

Validation of LIQ HD bout detection and bout microstructure in an ethanol two-bottle choice paradigm. A, Correlation between total bout number and change in bottle weight for each recording period. B, Correlation between total bout duration and change in bottle weight for each recording period. C, Correlation between percent preference calculated with bout number and percent preference calculated with change in bottle weight for each recording period. D, Correlation between percent preference calculated with bout duration and percent preference calculated with change in bottle weight for each recording period. Solid lines represent a fitted simple linear regression model, and dashed lines denote 95% confidence intervals. E, Preference over time in 1-h bins for the ethanol two-bottle choice paradigm. The solid line represents smoothed mean (sliding window length of 6), and shaded area signifies ±SEM (n = 8 cages). Vertical dashed lines indicate when bottles swapped sides and when indicated, a change of experimental solution in one bottle. F, Average preference for experimental bottle during ethanol two-bottle choice paradigm (repeated measures one-way ANOVA, with the Geisser–Greenhouse correction and Dunnett’s multiple comparisons test). Mice show significantly increased preference compared with baseline for 7% and 10% ethanol. Bout duration (G), bout size (I), lick frequency (K), and estimated interlick interval (M) over time in 24-h bins for water and ethanol bottles. Bout microstructure data were grouped into 24-h bins because there were no significant differences between the light and dark cycle (Extended Data Fig. 4-1). Average bout duration (H), bout size (J), lick frequency (L), and estimated interlick interval (N) during access to two water bottles and access to water with increasing concentrations of ethanol (repeated measures two-way ANOVA, with the Geisser–Greenhouse correction and Dunnett’s multiple comparisons test). At the ethanol bottle, mice display a significant decrease in bout duration (G), bout size (I), and interlick interval (N) with a significant increase in lick frequency (L) during access to increasing concentrations of ethanol. At the water bottle, mice display a significant increase in lick frequency only during access to 3% ethanol (L), a significant decrease in bout duration during access to 3% and 10% ethanol (H), and a significant decrease in bout size only during access to 10% ethanol (J). Shaded areas and error bars represent ±SEM; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.