Sessions científiques, CRG Group Leader Seminars
Sensory Systems and Behaviour Group, Systems Biology Programme, CRG
Matthieu Louis was brought to life sciences after being trained as a theoretical physicist at the Free University of Brussels (ULB). Gradually his interest in dynamical systems theory and complex systems shifted to the study of living matter. For his PhD at the European Bioinformatics Institute (EMBL outstation), he studied the regulatory logic of simple gene networks. In the group of Dr. Liisa Holm, he developed the first quantitative model for the process of sex determination in Drosophila - a textbook standard in developmental biology. He then joined the lab of Dr. Leslie Vosshall (Rockefeller University) where he received training in behavioral neurogenetics and sensory neuroscience. His postdoctoral research concentrated on the mechanistic basis of the peripheral encoding and the processing of olfactory stimuli in the Drosophila larva. In 2008 he started his own group at the CRG where perception and orientation behavior have remained a research focus. Using a systems perspective, the main question the Louis lab aims to address is how decision making and sensory-driven behaviors come about in terms of neural computation.
Chemotaxis is a powerful paradigm to investigate how nervous systems represent and integrate changes in sensory signals to direct navigational decisions. In the Drosophila melanogaster larva, chemotaxis consists of an alternation of distinct behavioral modes: runs and directed turns. Through sensory integration, turns are triggered by temporal decreases in odor intensity and, upon turning, the direction of motion is corrected with respect to the odor gradient. While the anatomy of the peripheral olfactory system and the locomotor system of the larva are reasonably well described, the neural circuits connecting the sensory neurons to the motor neurons remain elusive. We conducted a loss-of-function screen and gain-of-function perturbations to identify neurons that are necessary and sufficient for the control of reorientation behaviors in odor gradients. In this presentation, I will report our progress towards a systematic mapping of the neural circuitry participating in larval chemotaxis.