Stimulus Dependence of Visually Guided Behavior in Drosophila Melanogaster

Vision is very important for navigating the world around us. The fruit fly, Drosophila melanogaster, is a great model for studying how the brain controls visually guided behavior. This is because they have a small nervous system, good genetic tools, and a complete map of their brain connections. In fruit flies, visual projection neurons (VPNs) send information from the eyes to the central brain, which affects what they see and how they act. This research looks at how certain groups of nerve cells influence fruit flies' behavior based on what visual stimuli. To study the brain circuits behind these behaviors, I used genetic techniques to silence specific neurons. I targeted T4/T5 neurons, which are important for sensing motion and causing optomotor responses. I used tetanus toxin (TeNT). Initial tests showed strong optomotor responses in normal flies. However, blocking T4/T5 neurons with TeNT was lethal, suggesting these neurons are crucial for survival. I also studied how specific stimuli influence Drosophila behavior. I specifically focused on fixation (keeping their gaze steady) and optomotor responses (moving in response to visual motion). These are two key ways flies stabilize their view and stay oriented while moving. Using a special virtual reality setup, I looked at how changes in what they saw affected their walking and direction. I found that fixation responses were there, but weak, and when combined with optomotor stimuli, the optomotor response seemed to dominate fly behavior. Future work will use an exogenous expression of kir in T4/T5 neurons to carefully silence neurons and further explore how the brain controls behavior based on visual input. Overall, this project combines studying behavior with manipulating neurons to better understand how visual signals and specific brain cells work together to control attention and movement in fruit flies. This could also help us understand how sensory information is processed in more complex brains.