Movements in the fly’s eye

Lisa Fenk receives ERC Consolidator Grant for her research on retinal movements in fruit flies 

Lisa Fenk and her team at the Max Planck Institute for Biological Intelligence study visual processing in fruit flies. The group is particularly interested in the newly discovered retinal movements in the flies’ eyes – many of which are surprisingly similar to our own eye movements. In the coming years, Lisa Fenk wants to investigate how neurons process the visual information gained from these retinal movements and how this benefits the flies' visual perception. The project is funded by the European Research Council (ERC) with a Consolidator Grant of two million euros. 

Our eyes are constantly in motion: We track moving objects, scan our environment and even when our gaze is fixed on an object, our eyes never come to rest completely. Insects and many other arthropods, on the contrary, have rigid compound eyes that are firmly attached to their heads. It had been assumed that these animals could only change their visual fields by turning their heads or moving their bodies. However, Lisa Fenk and her colleagues in New York discovered that the eyes of some insects are less rigid than previously thought: Fruit flies have two small muscles that allow them to move the retinas underneath their stationary eye lenses. Interestingly, many of the retinal movements observed in fruit flies are very similar to our own eye movements. 

For example, fruit flies use their retinas to follow moving objects and to stabilize the perceived image. Even if nothing is moving in the animals’ visual environment, small, spontaneous retinal movements still occur. Compared to humans, a fruit fly’s field of view covers a much larger part of the environment. There is no need for flies to constantly scan their surroundings, as their eyes nearly cover the entire visual environment at any given moment. So, what is the purpose of the observed spontaneous retinal movements? Do they enable fruit flies to see things they would otherwise not perceive? And how is the process controlled? 

“Coordinating retinal movements in real time and in response to visual stimuli requires a lot of computing power from the neurons involved,” says Lisa Fenk. “We want to understand how the fly brain uses the information it obtains from retinal movements.” The investigation of this question is supported by an ERC Consolidator Grant of about two million euros over the next five years. For their work, Fenk and her team can employ many experimental methods and extensive knowledge about the nervous system in fruit flies. This is because the fruit fly visual system and the neuronal processes involved in vision have been studied for many years. 

The new insights gained in the project will be of broad interest for researchers studying fruit flies, other insects, and even vertebrates. “We hope that our findings in the fruit fly will complement ongoing research on other species. An overarching goal is to find the neuronal mechanisms that enable different animals to master similar visual challenges,” explains Lisa Fenk. “Why do flies and humans perform similar active eye movements despite their very different visual systems? That’s a question we are really excited about.”