Notre équipe combine génétique, biophysique, physiologie & comportement pour comprendre comment les entrées sensorielles sont intégrées dans la moelle épinière pendant le développement et la locomotion active. Nous avons découvert que des neurones inhibiteurs qui contactent le liquide céphalorachidien étaient mécanocepteurs qui détectent la courbure de la moelle épinière, et qui en retour modulent la locomotion et la posture. Nous utilisons la larve de poisson zèbre pour suivre et manipuler l'activité neuronale pendant le mouvement. Notre but est de comprendre comment les entrées sensorielles sont intégrées pendant la vie pour former et assurer l'homéostasie de la moelle épinière. A partir de cette recherche fondamentale, notre espoir est d'obtenir des résultats qui seront utiles chez l'homme.

recherche

Neuromodulation in hindbrain and spinal cord

Arousal locomotion is strongly modulated by our inner physiological states. This spontaneous exploratory locomotion reflects the excitability of motor circuits in the spinal cord as well as descending commands from the brain, in particular from the hindbrain. The underlying mechanisms controlling the occurrence of spontaneous locomotion and its natural variability among animals and across physiological states within one animal are not well understood. We are interested in probing neuromodulatory pathways in the hindbrain and spinal cord for setting the frequency of occurrence of locomotion in the context of circadian rhythm, inflammation and feeding.

Modulation of motor circuits via the cerebrospinal fluid

The classical view of spinal cord physiology relies on the fact that motor functions are carried by ventral spinal cord while dorsal spinal cord integrates sensory inputs from the periphery. Up to recently, there was no evidence that the vertebrate spinal cord carried itself sensory functions. Our team has shown evidence for a central sensory motor loop localized in the spinal cord and modulating circuits underlying locomotion and posture. We have evidence that the morphology and molecular markers of this central sensory system is conserved in the mammalian spinal cord.

Mechanosensory feedback to the spinal cord during active locomotion

The contribution of mechanosensory feedback to active locomotion and the nature of underlying spinal circuits remain elusive. We investigate how mechanosensory feedback shapes active locomotion in the zebrafish larva. We find that mechanosensory feedback enhances the recruitment of motor pools during active locomotion. We show that inputs from glutamatergic mechanosensory neurons increase locomotor speed by prolonging fast swimming at the expense of slow swimming during stereotyped acoustic escape responses. Altogether, our efforts reveal the basic principles and circuit diagram underlying speed modulation by mechanosensory feedback in the vertebrate spinal cord.

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