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Development of the cerebral cortex : recent findings from studies in mouse and primate Volume 20, issue 4, Octobre, Novembre, Décembre 2008

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Authors
Inserm, U839, Paris, France et Université Pierre et Marie Curie, Paris, France, Institut du Fer à Moulin, 17 rue du Fer à Moulin, 75005 Paris

The development of the cerebral cortex is a protracted process implying the generation of many different neuronal cell types. These neurons organize in layers and set functional networks and areas whose function range from basic perception to abstract thought. Although cerebral cortex has a very large expansion in human, its development is quite similar in mammals, from rodent to primates. Studies conducted in mice, using genetic approaches, allowed great advances in our understanding of cerebral cortical development during the last decade. Several sources for the cortical neurons were discovered, as well as different classes of pioneer cortical neurons. Tremendous progress has been made over these last years in identifying genes that specify the identity of cortical neurons, their migration pattern, as well as more complex features of their organization such as arealization, and axon network formation. Experiments conducted in primates confirmed these observations -or showed primate specificities. Thus, while principal glutamatergic and GABA interneurons originate from different primordia in mice, in primates, interneurones mostly arise from contical ventricular zone, as glutamatergic neurons do. Differences in the kinetics of cell division in the ventricular and subventricular cortical zone appear to control the expansion of the cerebral cortex and particularly of the upper cortical layers in primates. The better knowledge of the mechanism of cerebral cortex development that we have reached allows to understand better developmental disorders, from lamination defects to subtle disequilibrium in cortical networks. Such, anomalies underlie several neuropsychiatric disorders, including epilepsy.