Development of a robust and automated reward-delivery system for interval timing experiments in Drosophila

Interval timing allows animals to predict events based on temporal regularities. To investigate this ability in Drosophila melanogaster, we use a behavioral paradigm in which food-deprived flies receive repeated sucrose rewards at defined time intervals. Reliable reward delivery is essential for accurately characterizing the flies’ temporal responses. The current setup automates reward presentation using a motorized syringe, while a top-view camera records behavior. However, mechanical variability in syringe positioning, together with a suction system employed to remove the droplet, can lead to misalignment between the needle and the fly, inconsistent droplet formation, and failures during trials. These issues can compromise an entire experimental run and require manual intervention. We are therefore developing a more robust and automated reward-delivery platform. The syringe support is being redesigned to ensure reproducible alignment and prevent displacement during plunger movement. We are also developing an image-based method to estimate droplet volume from live camera recordings, aiming to use volume as a control variable for motor displacement. Ultimately, the platform will automate reward presentation while requiring only syringe loading and initial positioning, providing a reproducible setup for studying temporal learning in Drosophila. In the long term, this setup will allow to switch among either classical or operant conditioning protocols.