Columnar visual pathways for smooth optomotor steering and saccadic object tracking in Drosophila
- Author(s): Lopez, Ivan
- Advisor(s): Frye, Mark A
- et al.
All visual animals stabilize their gaze by moving their eyes, head, or body. Humans, with camera type eyes, use a “fixate and saccade” strategy that combines smooth tracking movements and ballistic eye saccades to stabilize gaze. Drosophila melanogaster, having a radically different type of eye, nonetheless move their full body during flight to use these smooth optomotor steering and saccade maneuvers to stabilize visual gaze. Despite the ubiquitous expression of these two behaviors across different species, the neural mechanisms that differentially control these maneuvers remain unknown. In this paper, we utilize the Gal4-UAS system to express a potassium inward rectifier, known as Kir2.1, in T4/T5, T2 or T3 columnar cells to test for differences in a flying fly’s ability to perform smooth optomotor steering and saccade maneuvers. Our data confirm prior work showing that T4/T5 neurons contribute motion related information to the downstream circuitry responsible for computing the speed of a moving panorama across the fly retina and accurately matching it to smooth fixational optomotor gain. We extend these results to show that T4/T5 are largely dispensable for the control of object tracking saccades. Additionally, our results strongly suggest that T2/T3 neurons contribute to the downstream circuitry responsible for target acquisition mechanisms required for recognizing and initiating saccadic tracking bouts in response to a moving barlike stimulus.