Data/hora: 15/06/2024 14:34:37

Provedor de dados: 	56	
País: 	Brazil	
Título: 	Critical steps in the early evolution of the isocortex: Insights from developmental biology	
Autores: 	Aboitiz,F.; Montiel,J.; López,J.	
Data: 	2002-12-01	
Ano: 	2002	
Palavras-chave: 	Cdk5; Dorsal ventricular ridge; Reelin; Tangential migration; Ventral pallium.	
Resumo: 	This article proposes a comprehensive view of the origin of the mammalian brain. We discuss i) from which region in the brain of a reptilian-like ancestor did the isocortex originate, and ii) the origin of the multilayered structure of the isocortex from a simple-layered structure like that observed in the cortex of present-day reptiles. Regarding question i there have been two alternative hypotheses, one suggesting that most or all the isocortex originated from the dorsal pallium, and the other suggesting that part of the isocortex originated from a ventral pallial component. The latter implies that a massive tangential migration of cells from the ventral pallium to the dorsal pallium takes place in isocortical development, something that has not been shown. Question ii refers to the origin of the six-layered isocortex from a primitive three-layered cortex. It is argued that the superficial isocortical layers can be considered to be an evolutionary acquisition of the mammalian brain, since no equivalent structures can be found in the reptilian brain. Furthermore, a characteristic of the isocortex is that it develops according to an inside-out neurogenetic gradient, in which late-produced cells migrate past layers of early-produced cells. It is proposed that the inside-out neurogenetic gradient was partly achieved by the activation of a signaling pathway associated with the Cdk5 kinase and its activator p35, while an extracellular protein called reelin (secreted in the marginal zone during development) may have prevented migrating cells from penetrating into the developing marginal zone (future layer I).	
Tipo: 	Info:eu-repo/semantics/article	
Idioma: 	Inglês	
Identificador: 	http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2002001200006	
Editor: 	Associação Brasileira de Divulgação Científica	
Relação: 	10.1590/S0100-879X2002001200006	
Formato: 	text/html	
Fonte: 	Brazilian Journal of Medical and Biological Research  v.35 n.12 2002	
Fonte: 	info:eu-repo/semantics/openAccess