Dr. Jacques Michaud is a physician in the Department of Medical Genetics at the CHU Sainte-Justine. His laboratory research concentrates on dissecting the developmental program of the paraventricular nucleus (PVN), a small group of neurons located in the hypothalamus. Its size and well-characterized cellular composition make the PVN an interesting model for studying the fundamental mechanisms controlling the differentiation of neurons and the generation of cellular diversity of the brain. PVN neurons participate in controlling a large number of physiological phenomena including appetite, thirst and response to stress. We have postulated that the study of PVN development will also allow us to better understand diseases affecting the physiological phenomena. In April 2006, the laboratory initiated an important research project focused on identifying genes responsible for mental retardation. During this five-year project, 300 genes involved in synapses will be studied in 285 subjects suffering from non-syndromic mental retardation. The most interesting variations will become the subjects of a more in-depth functional biological study.