A core interest of our research is the dissection of the cellular, molecular and epigenetic mechanisms of neuronal development using interdisciplinary experimental approaches. Currently, we exploit the unique genetic methodology called MADM (Mosaic Analysis with Double Markers) to dissect the fundamental principles controlling the development and assembly of the cerebral cortex in the mouse. With MADM it is for the first time possible to generate and visualize genetic mosaics allowing the functional analysis of virtually any gene in the whole mouse genome at unprecedented cellular resolution. By using this unparalleled approach we determine the molecular mechanism regulating neurogenesis and neuronal migration in the cortex, and analyze the cellular pathology associated with genes that when mutated in human cause severe neurodevelopmental disorders. In a second line of research we explore genomic imprinting (an epigenetic phenomenon) and its role in neurodevelopment.