Speaker
Description
Olfaction is crucial for appetitive search in hungry insects, as odor plumes carry information about food quality and location. Hunger enhances sensitivity and preferences to food-related odors, presumably to maximize the chance of meeting nutritional demands. However, how hunger promotes odor-guided appetitive search into environments with limited accessibility is unexplored. To address this question, we developed a behavioral paradigm using a custom Y-maze with a narrow passage connecting the entrance to the choice point, allowing simultaneous analysis of odor preference and odor-guided exploration through the narrow passage. Using this setup, we observed that hungry fruit flies Drosophila melanogaster are more likely guided to enter the narrow passage in the Y-maze, while most fed flies tend to remain not exploring. Compared to the fed group, the entry ratio of hungry flies to the choice point significantly increased with longer starvation hours and higher concentrations of an appetitive odor, suggesting feeding motivation. In a preliminary genetic screen to uncover the underlying neuromodulation mechanisms, we identified several neuropeptide mutants that showed higher entry ratios even when fed, suggesting a critical role of these neuropeptides in setting hunger state or odor sensitivity. This paradigm offers a new approach to uncover the mechanisms of hunger-driven odor preference and voluntary entry as a proxy for motivational regulation.
