Meeting Abstract
Dragonflies are excellent aerial predators that capture flying insects on the wing. Their success hinges on both the prey pursuit strategy and the preparatory head tracking that centers the target in the visual fovea to extract prey information. The dragonfly selectively pursues prey satisfying a certain range of angular size-speed ratio, and we have shown that such a heuristic rule effectively implements prey selection that screens out uncatchable prey. What’s the neural substrate for this heuristic? A class of target selective descending neurons (TSDNs) carry prey angular velocity information from the visual system in the head to the body and innervate various motor units such as wings and neck. TSDNs have receptive fields and directional selectivity that could guide the interception flight. One underappreciated feature of TSDNs is the coupling between the target size and speed preference. Specifically the target speed sensitivity depends on the target size and could contribute to the prey selection. To understand the visual-motor interactions required for prey pursuit, we first characterized the target size and speed tuning of TSDNs in an immobilized animal. Then, we used an RF powered telemetry backpack to record from TSDNs in the dragonfly during normal foraging behavior. The firing properties of TSDNs are consistent with the prey selection rule. By analyzing the timing of visual response relative to the motor activities of the head, we can determine whether TSDNs could drive the head tracking or collect target information after the prey has been centered. In addition, we can isolate the effect of head motor efference copy by replaying the reconstructed target projection to the eyes in a head-fix condition. Integrating these analyses will allow us to understand the true role of TSDNs in launching the dragonfly for a chase.
