Date of Award
Bachelor of Science
dragonfly, prey, wing angle, nerve, stimuli
Dragonflies have high visual acuity, which, when combined with a remarkably fast visual response, allows them to hunt small insects with a high success rate. Rather than aiming at the prey’s current location, the dragonfly predicts the prey’s future location and intercepts the insect mid-flight. Eight bilateral pairs of large Target-Selective Descending Neurons (TSDNs) of the dragonfly ventral nerve cord respond to small, contrasting objects, which presumably represent potential prey. These interneurons are part of the neuronal circuitry that triggers small changes in wing angle and position to control flight during prey interception. In flight, dragonflies extend their legs out to catch the prey about 20 ms before contact. The current research investigates the role of the TSDNs in prey contact. Spiking traces from the nerve cord were recorded during the presentation of expanding black circles projected on a screen, which simulate approaching prey. Several loom sizes and speeds were used to cover a range of realistic and unrealistic rates of expansion. I hypothesized that the interneurons predict the time to contact (Tc) of the simulated looming stimuli. Looming-sensitive TSDNs fired at a consistent time before Tc, supporting the hypothesis.
Gaffin-Cahn, Elon, "Neural Responses to Looming Objects in the Dragonfly" (2012). Honors Theses. 817.