Insect flight results from a neural cascade, in which sensory information is transformed into commands for wing and leg motion within less than 50 ms.

Flies possess a remarkable repertoire of sophisticated aerobatic behaviours such as centring and escape responses, collision avoidance, and an elaborate landing program. These aerial manoeuvres require elaborate sensory feedback coming from the gyroscopic halteres, the campaniform sensilla on the wings the ocelli and from the compound eyes. Our research aims to understand the complex dependencies between sensory feedback and motor control including the significance of aerodynamic limits on behavioural strategies and the precision of neuro-muscular control.

Tethered flies change flight direction by the production of yaw moments around the vertical body axis. When flown in a simulator under closed-loop feedback condition, the tethered flying animal actively controls the azimuth position of a visual object in the visual panorama by changing the difference between left and right wing beat amplitude. During this fixation behaviour the animal keeps the visual object in front of its visual field (see video).

To determine the significance of sensory feedback for flight control in a freely cruising fly, we investigate fruit flies flying in a free flight arena under various visual stimulus conditions. The fly’s aerial behaviour and thus motor actions are also compared with the output of the Hassenstein-Elementary-Motion Detector (EMD) of the compound eye in order to understand how visual feedback is converted into muscle commands for steering.

The integration of multiple sensory signals is critical for effective locomotor control in animals. Especially the impressive aerial performance of flies relies on the integration of visual steering commands with local and phasic mechanosensory feedback within milliseconds. Flight data show that mechanosensory feedback balances the temporal activation of flight muscles during vision-controlled manoeuvring. This process may favour a behaviour with optimal trade-off between flight stability and agility. Sensory integration in flies conceptually represents a neural local sensory feedback circuitry for motor control that has also been found in cats and humans.