Seminar – Matthias DURRIEU

Object manipulation and affordance learning in Drosophila

Animals interact with objects in their environment flexibly and efficiently, whether foraging for food or clearing obstacles from their path. This relies on mapping objects to the actions they permit, a concept known as affordance in ecological psychology. For objects an animal has never encountered before, this mapping must first be learned through experience. Although this has been described behaviorally across species, the neural circuits enabling it remain almost entirely unknown. Drosophila’s compact and genetically tractable brain makes it a well-suited system to fill this gap. In this context, Matthias Durrieu shows that adult flies also learn to push small spherical objects without any explicit reward. Flies first exposed to an immobile ball are delayed in pushing it once it becomes mobile. Flies trained on one ball also push a second, identical ball more readily in a new context. Both are hallmarks of affordance learning. A large-scale neural silencing screen reveals that specific visual projection neurons and olfactory sensory neurons regulate flies’ initial reactions to the object. In contrast, dopaminergic neurons acting on the mushroom bodies (a center for associative learning and memory in insects) are required for flies to generalize this learning to the second ball, showing that the effect reflects genuine affordance learning rather than simple habituation. Matthias Durrieu’s research combines closed-loop optogenetic perturbation with two-photon calcium imaging during ball pushing as a proof of concept, the next step toward understanding the circuit dynamics underlying how animals learn to act on the world.