title: Pallial patterning and the origin of the isocortex.
abstract: Together with a complex variety of behavioral, physiological, morphological, and neurobiological innovations, mammals are characterized by the development of an extensive isocortex (also called neocortex) that is both laminated and radially organized, as opposed to the brain of birds and reptiles. In this article, we will advance a developmental hypothesis in which the mechanisms of evolutionary brain growth remain partly conserved across amniotes (mammals, reptiles and birds), all based on Pax6 signaling or related morphogens. Despite this conservatism, only in mammals there is an additional upregulation of dorsal and anterior signaling centers (the cortical hem and the anterior forebrain, respectively) that promoted a laminar and a columnar structure into the neocortex. It is possible that independently, some birds also developed an upregulated dorsal pallium.
authors.affiliation: Facultad de Medicina, Centro de Investigación Biomédica, Universidad Diego Portales Santiago, Chile ; Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Montiel
authors.affiliation: Departamento de Psiquiatría, Escuela de Medicina, and Centro Interdisciplinario de Neurociencia, Pontificia Universidad Católica de Chile Santiago, Chile.
authors.forename: Francisco
authors.initials: F
authors.lastname: Aboitiz
keywords: Pax6; Wnt; antihem; hem; isocortical development