In different animal species, a variety of optical architectures and neuronal substrates have evolved for processing visual information. The systems of a few invertebrates have been studied intensively but there is still a white map for most of the known species. In this project I aim to have a closer look at the visual system of the praying mantis on ultrastructure level. Physiology studies in the praying mantis indicate that there is a special neuron, which responds to looming stimuli, in the lobula complex of the praying mantis. A similar looming sensing neuron was described in the visual system of the locust, named lobula giant movement detector (LGMD) and is characterized by its morphology and arrangement of the input-synapses it receives as well as by its excitation pattern. The experimental data revealed that the LGMD-like neuron of the praying mantis and the locust LGMD show similar excitation patterns in response to a simulated predator approach. I intend to conduct a study on the morphology and ultrastructure of this LGMD-like neuron. This will reveal if the neuron in question also poses the key features for reliable looming detection that have been described for the locust’s LGMD. For this purpose a newly developed technique will be used. The so called ATUMtome SEM allows us to collect several thousand ultra-thin sections on a tape and scan them in an SEM. This creates a volume of several hundred µm³ and gives us the opportunity to trace neurons or draw whole connectomes of a neuronal circuit within this volume. In order to elucidate how the LGMD-like neuron may operate, I aim not only to describe its morphology, but also to look at the nature of its input neurons and the type, number and distribution of synapses along the LGMD-like neuron.
2020 - 2024