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The postnatal growth of the callosal connections of primary and secondary visual cortex in the rat
Brain Research
|June 1, 1984
Insights
Callosal projection development finishes sooner in primary visual cortex than secondary. This indicates distinct developmental timelines for axon pruning and infiltration across different cortical areas.
Area of Science:
- Neuroscience
- Developmental Biology
- Visual Cortex Development
Background:
- Callosal projections connect homologous areas of the cerebral cortex.
- Understanding the developmental timing of these projections is crucial for comprehending cortical circuit formation.
Purpose of the Study:
- To investigate the developmental timeline of callosal projections in different visual cortical areas.
- To compare the maturation of areal and laminar distributions of callosal projections between primary and secondary visual cortices.
Main Methods:
- Analysis of callosal projection development in rodent models.
- Histological examination of axonal growth and distribution at specific developmental time points.
Main Results:
- Callosal projection growth is completed earlier in primary visual cortex (area 17) compared to secondary visual cortex (area 18b).
- Areal maturation in area 17 occurs by postnatal day 9, and laminar maturation by day 12.
- Areal and laminar maturation in area 18b are completed by postnatal days 12 and 15, respectively.
Conclusions:
- The developmental schedules for callosal axon pruning and infiltration differ between distinct cortical areas.
- These temporal differences in development may influence the functional maturation of visual processing circuits.
Abstract:
The growth of callosal projections is completed earlier in primary than in secondary visual cortex. In area 17, the areal and laminar distributions of callosal projections are mature by days 9 and 12, respectively, whereas in area 18b, these developmental milestones occur by days 12 and 15, respectively. This suggests that the pruning and infiltration of callosal axons follow different schedules in different cortical areas.