Student Theses and Dissertations
Date of Award
2025
Document Type
Thesis
Degree Name
Doctor of Philosophy (PhD)
Thesis Advisor
Vanessa Ruta
Keywords
olfactory navigation, drosophila, virtual reality, edge-tracking, mushroom body, spatial memory
Abstract
Animals rely on environmental cues, such as odors, to navigate through complex and often dynamic landscapes. While olfactory navigation has traditionally been modeled as a reflexive behavior driven by immediate sensory cues, whether flies can leverage more sophisticated strategies, integrating sensory input with spatial memory and internal representations of their surroundings, remains unclear. A key challenge in studying olfactory navigation lies in the invisible and unpredictable nature of odor plumes, which has made it challenging to accurately assess the ongoing sensory experiences of an animal. To address this challenge, we developed a novel virtual reality (VR) system that head-fixed Drosophila to navigate spatially structured chemical landscapes, enabling precise control and manipulation of their sensory experience. Using this platform, we demonstrate that Drosophila employs a robust navigational strategy known as edge-tracking, in which flies ascend along the boundaries of an odor plume through a repeated pattern of rapid counter-turning to exit the plume and biased exploration outside of the plume in order to return. Our findings suggest that edge-tracking is a flexible, memory-guided behavior, wherein flies continuously update their spatial representation of the plume's boundary based on sensory feedback. We further demonstrate that edge-tracking relies on dopaminergic reinforcement pathways within the mushroom body, a brain center that mediates associative olfactory learning. Anatomically, the mushroom body is well-positioned to modulate edge-tracking behavior due to its many connections with other key brain regions involved in spatial navigation and motor control, including the central complex. Our results show that optogenetic manipulations disrupting dopaminergic input to the mushroom body can promote or disrupt edge tracking, underscoring the importance of these reinforcement signals during ongoing navigation. Through a combination of behavioral experiments, modeling, and neural circuit manipulations, this work provides new insights into the mechanisms that support olfactory navigation in complex environments. By studying their behavior in a controlled virtual environment, we demonstrate that flies engage in sophisticated olfactory navigational strategies that extend beyond simple reflexive responses to sensory cues. Instead, they rely on the integration of sensory input with spatial memory to navigate through their environment.
License and Reuse Information
This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.
Recommended Citation
Morton, Chad, "A Scent of Direction: Exploring Adaptive Olfactory Navigation in Drosophila" (2025). Student Theses and Dissertations. 818.
https://digitalcommons.rockefeller.edu/student_theses_and_dissertations/818
Comments
A thesis presented to the faculty of The Rockefeller University in partial fulfillment of the requirements for the degree of Doctor of Philosophy