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Ex utero Electroporation and Whole Hemisphere Explants: A Simple Experimental Method for Studies of Early Cortical Development
Published on: April 3, 2013
The early differentiation of the neocortex: a hypothesis on neocortical evolution
1Graduate School of Neurosciences Amsterdam, Department of Visual System Analysis, AMC, University of Amsterdam, PO Box 12011, 1100 AA Amsterdam, The Netherlands. h.super@ioi.knaw.nl
Cerebral Cortex (New York, N.Y. : 1991)
|November 16, 2001
Summary
The mammalian neocortex
Area of Science:
- Neuroscience
- Developmental Biology
- Evolutionary Biology
Background:
- The cerebral cortex develops from the telencephalic vesicle in reptiles and mammals.
- A primordial preplate gives rise to a cell-dense cortical plate, crucial for neuronal development.
- Preplate neurons regulate cortical plate neuron migration and form initial axonal connections.
Purpose of the Study:
- To investigate the evolutionary implications of differing axonal entry points in reptilian versus mammalian neocortical development.
- To propose a hypothesis explaining how neocortical expansion is facilitated by specific developmental pathways.
Main Methods:
- Comparative analysis of cortical development in reptiles and mammals.
- Discussion of neuronal migration patterns and axonal connectivity.
- Evolutionary hypothesis formulation based on developmental observations.
Main Results:
- In reptiles and mammalian hippocampus, afferent axons enter above the cortical plate, interacting with pyramidal neuron dendrites.
- In the mammalian neocortex, axons primarily enter below the cortical plate, bypassing apical dendrites.
- This difference suggests a functional constraint was lifted in neocortical evolution.
Conclusions:
- The entry of axons below the cortical plate in mammals, coupled with inside-out neuronal migration, maintains the neocortex as an 'open' system.
- This openness allows for the differentiation of new sublayers and cortical areas, driving neocortical expansion.
- This developmental strategy is key to the evolutionary success and complexity of the mammalian neocortex.
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