36 - Cortical Development and Disorders

Abstract

Cortical neuronal cell development starts at about 7 weeks' gestation from stem cells in the germinal matrix that line the ventricles. The stem cells proliferate and differentiate into glial cells and neurons. The glial cells migrate radially to the brain surface and create a scaffold for the neurons to follow to the outer cortex, where the neurons organize connections and commissures. Other neurons derived from the ganglionic eminence migrate tangentially to form inhibitory neurons and basal ganglia. Rapid development occurs at about 15 to 20 weeks' gestation. By about 30 weeks' gestation, neuron development is completed, resulting in the six cortical layers. Neurons are formed in larger numbers than needed, and more than half undergo apoptosis.