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A novel cytoarchitectonic area induced experimentally within the primate visual cortex.
P Rakic1, I Suñer, R W Williams
1Section of Neuroanatomy, Yale University School of Medicine, New Haven, CT 06510.
Summary
Altering thalamic input to the primary visual cortex (area 17) in developing monkeys created a new brain area, area X. This finding suggests how new cortical areas may evolve through unique cell interactions.
Area of Science:
- Neuroscience
- Developmental Biology
- Comparative Anatomy
Background:
- The cerebral cortex has distinct cytoarchitectonic areas.
- Mechanisms controlling the number and size of these areas are not well understood.
Purpose of the Study:
- To investigate the developmental mechanisms behind the formation of cortical areas.
- To explore how alterations in thalamic input influence cortical development.
Main Methods:
- Midgestational reduction of specific thalamic fibers projecting to the primary visual cortex (area 17) in monkeys.
- Cytoarchitectonic analysis of the resulting cortical structure.
Main Results:
- A novel cytoarchitectonic area, termed area X, was induced.
- Area X was located along the border of and within area 17.
- Area X exhibited distinct cytoarchitectural features compared to areas 17 and 18.
Conclusions:
- Aberrant thalamic and cortical connections can lead to the formation of hybrid cortical areas.
- Supports the protomap hypothesis of cortical organization.
- Suggests a mechanism for the evolution of new cytoarchitectonic regions through cell interactions.