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Sensory logic of odor perception in Drosophila larvae

Orateur :

Matthieu Louis, Sensory Systems and Behaviour, Centre for Genomic Regulation, Barcelona

Salle :

C023 (RDC LR6 côté CECAM)

Quand :

12/11/2008 à 11:00

Sujet :

Chemotaxis involves directed navigation toward attractive stimuli and away from aversive stimuli. Although this process is critical for the survival of all motile animals, the mechanisms by which higher organisms with complex nervous systems navigate through chemical gradients remain poorly described. We are studying this problem in Drosophila larvae which represent a powerful paradigm to investigate the principles of odor coding. To characterize the navigation strategies of larvae, we developed a novel chemotaxis assay where odorant conditions can be both measured and controlled. Using high-resolution computerized analysis of individual animal trajectories, we showed that Drosophila larvae advance up an odorant gradient by constantly aligning their direction of motion with that of the local odorant gradient.

We manipulated the larval olfactory system to generate animals with an altered repertoire of odorant receptors. Animals possessing only a single pair of functional olfactory sensory neurons – one on each side of the head - were generated and showed robust chemotaxis. The complexity of the system was further reduced by genetically engineering larvae with a single olfactory neuron in either the right or left side of the head. Our behavioral results provide evidence that, while bilateral olfactory input is not essential for larval chemotaxis, it enhance the accuracy of the chemotactic navigation by increasing the signal-to-noise ratio in odor detection

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