Genetic control of neuronal migrations in human cortical development.

The early steps in corticogenesis are decisive for the correct unfolding of neurogenesis, neuronal migration and differentiation under tight genetic control. In this monograph, we outline the main events in human preplate formation, the gradual transformation of the preplate into the cortical plate, and the establishment of the transient compartments of the foetal cortical wall. The main neuronal populations of the embryonic and fetal cortex are presented according to their timetable of appearance and the expression of developmentally relevant gene products, with the main focus on members of the Reelin-Dab1 signalling pathway, LIS1 and Doublecortin, all of which are crucial for cortical migration. The often significant developmental differences between the lissencephalic rodent brain, which has become the prevailing model of corticogenesis, and the highly differentiated, gyrated human brain are pointed out and discussed.