FIGURE 8-9 Prenatal Development of the Human Cerebral Cortex Brain weight and body weight increase rapidly and in proportion. The cortex begins to form about 6 weeks after conception, with neurogenesis largely complete by 25 weeks. Neural migration and cell differentiation begin at about 8 weeks and are largely complete by about 29 weeks. Neuron maturation, including axon and dendrite growth, begins at about 20 weeks and continues until well after birth.

Information from M. Marin-Padilla (1993). Pathogenesis of late-acquired leptomeningeal heterotopias and secondary cortical alterations: A Golgi study. In A. M. Galaburda (Ed.), Dyslexia and development: Neurobiological aspects of extraordinary brains. Cambridge, MA: Harvard University Press.