Active Vision in Blowflies: Strategies and Mechanisms of Spatial Orientation

With its miniature brain blowflies are able to control highly aerobatic flight manoeuvres and, in this regard, outperform any man-made autonomous flying system. To accomplish this extraordinary performance, flies shape actively by the specific succession of characteristic movements the dynamics of the image sequences on their eyes (‘optic flow’): They shift their gaze only from time to time by saccadic turns of body and head and keep it fixed between these saccades. Utilising the intervals of stable vision between saccades, an ensemble of motion-sensitive visual interneurons extracts from the optic flow information about different aspects of the self-motion of the animal and the spatial layout of the environment. This is possible in a computationally parsimonious way because the retinal image flow evoked by translational self-motion contains information about the spatial layout of the environment. Detection of environmental objects is even facilitated by adaptation mechanisms in the visual motion pathway. The consistency of our experimentally established hypotheses is tested by modelling the blowfly motion vision system and using this model to control the locomotion of a ‘Cyberfly’ moving in virtual environments. This CyberFly is currently being integrated in a robotic platform steering in three dimensions with a dynamics similar to that of blowflies.