Date of Award

6-2020

Document Type

Union College Only

Degree Name

Bachelor of Science

Department

Neuroscience

First Advisor

Robert Olberg

Keywords

Dragonfly, vison, TSDN, Aeshnid

Abstract

Research has suggested that a set of neurons called TSDNs (target-selective descending neurons) in dragonflies are responsible for visual prey pursuit, and these neurons have been shown to produce wing and head movements when stimulated individually. The TSDNs receive visual information from the compound eyes of the dragonfly and relay this information to the motor centers in the thorax that control wing and head movement. In my experiment, I stimulated half of the ventral nerve cord with a silver hook electrode to analyze the movement of the wings and head elicited by the combined activity of the TSDNs on one side of the nervous system. The TSDNs of various dragonfly subjects were stimulated at varying voltages, and wing movements were tracked to determine the effects of these voltages on head and wing movement, as well as the effects of a neurohormone and raised body temperature.

Our data suggest that dragonflies begin to respond to 250 Hz pulses at voltages as low as 0.3 volts, and tend to reach their peak movement 2.0 volts. Wing movements become larger and more pronounced with increasing voltage until around 2.0 volts, after which point changes in movement intensity are negligible. Of the four animals who’s wing movements were analyzed, there was no observable pattern of the direction and rotation of wing movements between different subjects.

The effects of chlordimeform (CDM), an octopamine mimic, were studied, to determine whether there was a difference in the amount of wing movement seen before and after treatment. I also studied the effect of increased body temperature on stimulated wing and head movements. These data suggest that CDM did have an effect on wing movement, and administration of this drug resulted in wing movements that were larger and more wavering. There were no observable changes in behavior with increased body temperature.

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