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Updated: Mar 31, 2026
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Ex utero Electroporation and Whole Hemisphere Explants: A Simple Experimental Method for Studies of Early Cortical Development
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Pallial patterning and the origin of the isocortex.
Juan F Montiel1, Francisco Aboitiz2
1Facultad 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.
Frontiers in Neuroscience
|October 30, 2015
Summary
Mammalian neocortex evolution involved conserved brain growth mechanisms, Pax6 signaling, and unique upregulation of specific signaling centers. This led to the characteristic laminated and columnar structure found only in mammals.
Area of Science:
- Neuroscience
- Evolutionary Biology
- Developmental Biology
Background:
- Mammals possess a highly developed isocortex (neocortex) with a unique laminated and radially organized structure.
- This contrasts with the brain organization observed in reptiles and birds.
Purpose of the Study:
- To propose a developmental hypothesis for evolutionary brain growth in amniotes.
- To investigate the conserved and divergent mechanisms underlying neocortex formation.
Main Methods:
- Comparative analysis of developmental signaling pathways across amniotes.
- Focus on the role of Pax6 signaling and related morphogens.
Main Results:
- Evolutionary brain growth mechanisms are partially conserved across mammals, reptiles, and birds, involving Pax6 signaling.
- Mammals exhibit unique upregulation of dorsal (cortical hem) and anterior (anterior forebrain) signaling centers.
- This upregulation is hypothesized to drive the laminar and columnar organization of the neocortex.
- Some bird species may have independently evolved an upregulated dorsal pallium.
Conclusions:
- The evolution of the mammalian neocortex relies on both conserved developmental pathways and novel signaling center upregulation.
- Pax6 signaling plays a fundamental role in amniote brain evolution, with differential regulation leading to distinct cortical structures.
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