Reorganization of columnar architecture in the growing visual cortex

Area of Science:

• Neuroscience
• Developmental Biology
• Computational Neuroscience

Background:

• Cortical areas grow significantly during postnatal development, leading to neuronal displacement.
• The impact of this cortical expansion on neuronal circuit development remains poorly understood.

Purpose of the Study:

• To investigate how postnatal cortical growth influences the spatial organization of ocular dominance (OD) columns in the primary visual cortex.
• To identify the mechanisms underlying the preservation of OD column spacing and the observed changes in their arrangement during development.

Main Methods:

• Acute and chronic experiments were conducted on cat primary visual cortex.
• The study analyzed the layout and spatial arrangement of ocular dominance columns.
• A computational model, the Elastic Network model, was used to simulate and analyze the observed phenomena.

Main Results:

• Despite substantial cortical expansion, the spacing between ocular dominance columns is largely preserved.
• The spatial arrangement of OD columns transitions from band-like in young animals to more isotropic in mature animals.
• The "zigzag instability" mechanism was proposed and shown to explain both the preservation of column spacing and the observed reorganization.

Conclusions:

• Cortical circuits maintain plasticity during development to accommodate growth.
• Neuronal selectivities systematically reorganize during cortical expansion, preserving column width.
• The "zigzag instability" provides a robust model for activity-dependent OD column formation and reorganization during brain development.