Role of the caudal appendage during locomotion in the Urodele: kinematic and electrophysiological study
Defended on December 15, 2014
Tetrapod locomotion involves rhythmic and coordinated movements of the limbs and body. The locomotor movements of the limbs and their neural control have been extensively studied. In contrast, studies addressing the movements of the body during locomotion are rare and limited to the trunk, while in many species the caudal appendage plays a crucial role in maintaining dynamic balance during locomotion. The goal of my doctoral work was to characterize the caudal movements during locomotion in Urodeles and to identify the underlying neural mechanisms. This species was chosen because of the diversity of its aquatic and terrestrial locomotor modes. A combination of kinematic and EMG recordings in freely moving animals have evidenced complex and variable caudal movements and muscle activity patterns, depending on the environment and locomotor mode used. In vitro electrophysiological recordings have demonstrated the existence of a neural network generating the movements of the caudal appendage. This network is a double chain of hemi-segmental oscillators distributed all along the caudal spinal cord. Glutamatergic excitatory connections are essential for segmental rhythmogenesis and glycinergic inhibitory connections control the coupling between hemi-oscillators. Finally, we have shown that the coupling between trunk and caudal locomotor networks involves short intra-spinal connections In conclusion, our work suggests a functional modularity of the axial locomotor network in Vertebrates. This modularity enhances their adaptive capacity to move in changing environment.
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- Anick ABOURACHID
MC, Rapporteur – Muséum National d’Histoire Naturelle – Paris, France
- Michèle ALLARD
PU Bordeaux, EPHE, France – Co-directrice
- Jean-Marie CABELGUEN
PU Bordeaux, France – Co-directeur
- Jean-René CAZALETS
DR, CNRS, Bordeaux, France – Président
PU Québec, Montréal, Canada – Rapporteur
- Raul RUSSO,
Professeur, Instituto Clemente Estable, Montevideo, Uruguay – Examinateur
Professeur de Biophysique et Médecine Nucléaire.
Université de Bordeaux
INSERM U862 – Neurocentre Magendie
Equipe: Motor System Diseases Team