Dragonflies have compound eyes that wrap around their head, allowing them to see 360°. As a result, dragonflies can see objects that move both behind them and in front of them. Little is known about the backward-looking part of the dragonfly visual system. However, one neuron, called DMT1, which is in the dorsal median tract of the ventral nerve cord has been known to respond only to objects moving behind the animal. Based on recent research, we have evidence of four backward-looking cells in the Aeshnid dragonfly, of which two are looming cells, i.e. neurons that respond preferentially to approaching objects. The other two are target-selective cells, i.e. neurons that respond to objects moving behind the animal. I have developed a preparation to determine the precise receptive fields and anatomical locations of these backward-looking cells using dye-filled intracellular microelectrodes.
The dragonfly was positioned ventral side up with the posterior portion of the eye facing a projection screen, which showed looming stimuli and moving-target stimuli of different sizes and speeds. The ventral nerve cord was exposed to allow penetration of single axons with a glass microelectrode. Upon sustained penetration, I injected the fluorescent dye, Lucifer Yellow, in an attempt to identify, for the first time, the structure of the backward-looking neurons in the dragonfly ventral nerve cord.