Neuronal Migration and Neuronal Migration Disorder in Cerebral Cortex

Abstract

Neuronal cell migration is one of the most significant features during cortical development. After final mitosis, neurons migrate from the ventricular zone into the cortical plate, and then establish neuronal lamina and settle onto the outermost layer, forming an inside-out gradient of maturation. Neuronal migration is guided by radial glial fibers and also needs proper receptors, ligands, and other unknown extracellular factors, requests local signaling (e.g. some emitted by the Cajal-Retzius cells of the marginal zone) to stop neuronal migration. This process is highly sensitive to various physical, chemical and biological agents as well as to genetic mutations. Any disturbance of the normal process may result in neuronal migration disorder. Such neuronal migration disorder is believed as major cause of both gross brain malformation and more special cerebral structural and functional abnormalities in experimental animals and in humans. A number of instructive studies on nongenetic models (e.g. MAM- or irradiation-treated rodents) and mutations (e.g. Reelin- or Tish-mutant animals) have established the foundation of cortex formation and provided a framework in which to understand mutants of cortex development. The recent studies on several genetic model systems of neuronal migration disorder provide further insight into the development pathways that underlie normal and abnormal neuronal migration.