Major events in the development of the forebrain

The development of the central nervous system can be divided into a number of phases, each of which is characterized by particular developmental disor ders. In recent years, much progress has been made in elucidating the mecha nisms by which the forebrain develops and in our understanding of major dev elopmental disorders such as holoprosencephaly and neuronal migration disor ders. In this general introduction to this symposium the major stages in th e development of the forebrain, its regionalization and the genes involved, and some of the developmental disorders derailing cortical development wit h subsequent damage to the main cortical fiber connections (pyramidal tract and corpus callosum) are discussed.