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Accueil du site → Doctorat → Allemagne → Processing of sky compass signals at different stages of the polarization-vision pathway in the brain of the desert locust (Schistocerca gregaria)

Philipps-Universität Marburg (2011)

Processing of sky compass signals at different stages of the polarization-vision pathway in the brain of the desert locust (Schistocerca gregaria)

el Jundi, Basil

Titre : Processing of sky compass signals at different stages of the polarization-vision pathway in the brain of the desert locust (Schistocerca gregaria)

Auteur : el Jundi, Basil

Université de soutenance : Philipps-Universität Marburg

Grade : Doktorgrades der Naturwissenschaften (Dr. rer. nat.) 2011

Description
Although insect brains are small in comparison to those of vertebrates, some species show astonishing navigational abilities. Desert locusts (Schistocerca gregaria) are well-known for forming huge swarms consisting of millions of animals and their long-range migrations throughout North Africa and the Middle East. Experiments on tethered flying locusts showed that the animals respond with a 180°-periodicity of yaw-torque to a dorsally rotating polarizer. This suggests that locusts are able to use celestial polarized light as navigational cue during spatial orientation and navigation. A number of recent studies have explored the neural basis of sky compass orientation in locusts by focusing on the processing of polarized light signals in the brain. In contrast, (1) the mechanisms of compensation for changes of solar position over the course of the day and (2) the integration of different signals from the sky (polarization pattern, solar position, chromatic gradient) are poorly understood, particularly at the level of the optic lobe. Finally, (3) no data exist comparing the sky compass system in diurnal gregarious locusts with that of nocturnal solitarious locusts. Towards these goals, polarization-sensitive neurons at different levels of the polarization vision pathway were analyzed physiologically through intracellular recordings and anatomically by means of detailed three-dimensional reconstructions of neuronal arborizations. First, neurons of the medulla in the optic lobe were analyzed and characterized to understand the combination and integration of sky compass information in the locust brain.

Mots Clés : Insektengehirn , Himmelskompasssignle , Zentralkomplex , räumliche Orientierung , visuelles System ; insect brain , vision , orientation , polarized light , sky compass signals

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Page publiée le 19 mai 2012, mise à jour le 5 janvier 2019