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Afferent control of neuron numbers in the developing brain.
1Instituto de Biofisica da UFRJ, Rio de Janeiro, Brazil.
Brain Research. Developmental Brain Research
|December 1, 1988
Summary
The size of incoming nerve connections influences how many brain cells survive during development. This suggests that nerve supply size is key for determining neuron numbers in the developing brain.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Neuronal development involves precise matching between innervating and target populations.
- The role of afferent supply size in regulating target neuron survival during natural cell death is not fully understood.
Purpose of the Study:
- To investigate if the quantitative matching of developing neuronal populations is dependent on the size of the afferent supply.
- To determine the impact of afferent neuron numbers on the survival of target neurons during development.
Main Methods:
- Partial deafferentation of the middle division of the parabigeminal nucleus (PBm) was performed in developing subjects.
- This deafferentation was achieved by reducing the neuronal population of the superior colliculus via partial lesions or eye removal.
- The number of surviving neurons in the PBm was quantified after the period of natural cell death.
Main Results:
- A linear relationship was observed between the number of surviving PBm neurons and the number of their afferent neurons.
- Partial deafferentation did not prevent neuronal survival but modulated the final neuron number in the PBm.
Conclusions:
- The size of the afferent neuronal supply is a significant factor in determining the number of target neurons that survive during natural cell death.
- Neurotrophic factors provided by the afferent supply play a critical role in regulating neuronal population size during brain development.