Optic flow processing centers: the crab doesn?t fall far from the arthropod phylogenetic tree

JULIETA SZTARKER

Congreso; FALAN networking: Bringing latinoamerican and caribean neuroscience together; 2021

FALAN

When an animal rotates it produces wide drift of the visual panorama occurs over its retina, termed optic flow. These images are stabilized by compensatory behaviors (driven by the movement of the eyes, heads or the whole body depending on the animal) collectively termed optomotor response (OR). It has long been known that, in the visual system of flies, the lobula plate is the center involved in optic flow analysis and in guiding OR. The visual neuropils of crustaceans and insects are similarly organized (three nested neuropils connected by 2 chiasmata) which led some authors to propose a close evolutionary relationship between the groups. Recently, a crustacean lobula plate was characterized by neuroanatomical techniques in the mud crab Neohelice granulata, sharing many canonical features with the dipteran neuropil. This leads to the question if a common role is also shared. In this series of experiments, we tackle that question by performing electrolytic lesions followed by behavioral testing. Result show that crabs with injured lobula plates largely failed to execute OR (or present a poor and unsynchronized response) in comparison to both control-lesioned (presenting a lesion of similar size but in another region of the optic neuropils) and non-lesioned animals. The lesion of the lobula plate cause a specific impairment in the OR, as proved by the fact that antipredatory responses to an approaching visual stimulus did not change between groups. These results present strong evidence about a conserved site for processing optic flow shared by crustacean and insects.