Looming detection is crucial for animals to efficiently respond to approaching stimuli. Extensive research has been done to characterise and understand the neural circuits underlying such capacity. The locust has been established as a preferred model because it has a pair of large and uniquely identified visual neurons, the lobula giant movement detector (LGMD) and the postsynaptic descending contralateral movement detector (DCMD) that respond selectively to the images of an object approaching towards its eye. These neurons have been associated with the triggering of last moment avoidance responses such as gliding dives during flight. So far, all studies have used adult locusts. However these animals avoid predation by birds throughout their lives and the preferred escape response varies during development. Juvenile locusts display escape behaviours on the ground, such as hiding and jumping, that require more time than emergency dives and therefore are triggered early in the loom. DCMD may have a role in guiding these early reactions as it starts responding long before collision. However there have been no attempts yet to record from the DCMD during hiding. The present research aims at characterising the visual cues that produce the hiding response in the adult and studying the possible involvement of the LGMD and DCMD neurons in such behaviour. It also intends to quantify the behavioural strategies displayed at different stages of the locust’s life, relating them to the development of the neural circuit involved in looming detection. For this study we will use electrophysiological recordings in juvenile and adult locusts. We will also study the ultrastructure and synaptic connections during development, and relate it to what is already known in the adult. This may lead to a better understanding of the LGMD-DCMD circuitry and an improvement of the biologically inspired robots and warning sensor for imminent collisions in cars that are already based in such circuit.
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