Patterns of neuronal migration in the embryonic cortex.

Real-time imaging of migrating neurons has changed our understanding of how newborn neurons reach their final positions in the developing cerebral cortex. The migratory routes and modes of migration are more diverse and complex than previously thought. The finding that cortical interneurons migrate to the cortex from origins in the ventral telencephalon has already markedly altered our view of cortical migration. More recent findings have demonstrated additional nuances in the migratory pattern and highlighted differences between subsets of interneurons. Moreover, radial migration of pyramidal neurons does not progress smoothly from ventricle to cortical plate, but is instead characterized by distinct migratory phases in which neurons change shape and direction of movement. Integrating these findings with the molecular machinery underlying migration will provide a more complete picture of how the cerebral cortex is assembled.