LIQ HD - Lick Instance Quantifier Home cage Device
UPDATE: 1/19/2024 (Arduino Mega version only)
We have now included the ability to log the lick data by individual bouts! With this setting turned on, each individual bout will be logged with a line in the file with the side the experimental bottle is on (LEFT or RIGHT), a time stamp, the cage number, which bottle was licked (LEFT or RIGHT), bout lick number, bout lick duration, average lick frequency of that bout, and average inter-lick interval of that bout. Note, this setting will not log the total lick number and lick duration (i.e. licks that do not meet bout criteria).
The "log by bout" setting can be turned on using the GUI under "Parameters to log". This setting can be made the default by changing the Arduino code lines 186-187. For example:
bool log_by_bout = true; bool log_by_time = false; //will set the default to "log by bout".
bool log_by_bout = false; bool log_by_time = true; //will set the default to "log by time" (original logging method).
We have also made it easier to change the bout cutoff time (the amount of time during a drinking bout where an animal stops licking before the bout is considered over) by changing the "bout_cutoff" variable on line 185.
We made some minor changes to the capacitive sensor settings that optimizes the baseline tracking for more consistent lick detection.
Included in this repository:
- Arduino code for LIQ HD running off an Arduino Mega
- Arduino code for LIQ HD running off an Adafruit Grand Central (significantly faster processor speed. NOT FULLY TESTED.)
- 3D models for all required 3D-printed components in various file formats (STL, STEP, SHAPR)
- Step-by-step build instructions and video tutorial can be found on the Wiki page
Required Arduino Libraries:
- Adafruit_GFX.h
- RTClib.h
- SdFat.h
- Adafruit_MPR121.h
- Adafruit_ILI9341.h
- Adafruit_FT6206.h
Publication Link: https://www.eneuro.org/content/10/4/ENEURO.0506-22.2023
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 periodically 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, recent designs are limited by the use of infrared photobeam-break sensors and incompatibility with prolonged undisturbed use in ventilated home cages. Beam-break sensors lack accuracy for bout microstructure analysis and are prone to damage from rodents. To address these concerns, we designed LIQ HD (Lick Instance Quantifier Home cage Device) with the goal of utilizing capacitive sensors to increase accuracy and analyze lick microstructure, building a device compatible with ventilated vivarium 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 home 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. With sucrose, quinine, and ethanol two-bottle choice tasks, we validated that LIQ HD has superior accuracy compared to beam-break sensors. The system measures preference over time and changes in bout microstructure, with undisturbed recordings lasting up to 7 days. All designs and software are open-source to allow other researchers to build upon the system and adapt LIQ HD to their animal home cages.
