Study of embryonic development, its large-scale phylogenetic evolution, and its physiology in mice.

A long line of biologists, from the physiologist Xavier Bichat (1771-1802) to the paleontologist Alfred Romer (1894 -1973), have described the vertebrate body in general, and its nervous system in particular, as made of two parts, one somatic and one visceral, “imperfectly welded onto each other”: the somatic part deals with “external affairs” (i.e. our relation to the environment), the visceral part deals with “internal affairs” (i.e. homeostasis, through the control of respiratory, cardiovascular and digestive functions). In a striking echo of this view, we discovered some years ago that the majority of the constituent neurons of the visceral circuits (sensory neurons of epibranchial ganglia, ganglionic autonomic neurons, their preganglionic neurons, and several classes of interneurons) share a dedicated transcription factor, Phox2b, a veritable “master gene” of the visceral circuits, which sets them apart from somatic neurons. This ontogenetic unity—which makes visceral reflex circuits, collectively, one organ, and visceral neurons, collectively, one class (or super-class) of neurons—, informs much of our work. We study simultaneously several parts of the visceral circuits, and from several perspectives: embryological, physiological and evolutionary, each line of research contextualized by the others.

Current physiological work, under the direction of Gilles Fortin who joined us at the ENS, concerns respiration, one of the three cardinal visceral functions, with blood circulation and digestion. Respiration is a vital behavior, relatively simple and conserved among vertebrates. In this model, we aim to identify the principles by which neural circuits orchestrate the precise and timely control of behavior. We seek to understand how the nervous system can generate/modulate ongoing rhythmic activity and compute the neural commands that mediate homeostatic aspects of breathing (gas exchange in the lungs) and non-homeostatic ones (e.g., vocalization). To decipher how brainstem respiratory circuits engage in the control of various functional tasks, we need to unravel the neural subpopulations organized into specific circuits with dedicated executive functions. These questions are addressed through multiple approaches that include state-of-the-art genetics in mice, viral tracing strategies, functional manipulation (opto-/chemo-genetics) and biophysical (e.g., electrophysiology, calcium imaging...) and video tracking for quantitative behavioral analysis. Thanks to investigations at different stages of development, these approaches also touch upon the mechanisms of circuit assembly.

Address :
46 Rue d'Ulm, 75005, Paris

Team leader :
Brunet Jean-François
Name of co-team leader :

Administrative Contact Name :
VILLA Tommaso

Website : Cliquez ici
Key words : #opto-/chimio-génétique#électrophysiologie#imagerie calcique#vidéo tracking #opto-chemo-genetics#electrophysiology#calcium imaging#video tracking