CONICET | Buscador de Institutos y Recursos Humanos

Phototaxis is an iconic example for behaviors dominated by innate components orpreferences. Such preferences likely reflect evolutionary adaptations to predictablesituations, and the behaviors dominated by them have traditionally been conceptualizedas hard-wired stimulus-response links. Perhaps therefore, the century-old discovery ofplasticity in Drosophila phototaxis has received little attention. Experiments performed byMcEwen demonstrated that wing defects, caused by mutation or damage, profoundlyaffect phototaxis in walking Drosophila1. The fact that manipulating an unrelated organ,such as wings, affects phototaxis contradicts the assumed hard-wired organization of thisbehavior, suggesting that it may not be a simple stereotypic and automatic response, butthat it contains at least a certain element of flexibility. To explore this hypothesis in ourlaboratory, walking flies were tested for their light/dark preference in several differentbehavioral tests. Interestingly, light/dark preference tested in walking flies is dependenton various aspects of flight. If flying ability is temporarily compromise, photopreferencereverses concomitantly. Neuronal activity in circuits expressing dopamine andoctopamine, respectively, plays a differential role in photopreference, suggesting apotential involvement of these biogenic amines in this case of behavioral plasticity. Weconclude that flies monitor their ability to fly, and that flying ability exerts a fundamentaleffect on action selection in Drosophila. This work suggests that even behaviors whichappear simple and hard-wired comprise a value-driven decision-making stage,negotiating the external situation with the animal?s internal state before an action isselected.Moreover, if even this iconic and simple hard-wired behaviour consist of an actionselection step, more complex behaviours should be also built on decision-making blocks.