Development and plasticity of the cerebral cortex: from molecules to maps

Area of Science:

• Neuroscience
• Developmental Biology
• Systems Biology

Background:

• Environmental influences on nervous system development are extensively studied.
• Characterizing activity-dependent and -independent processes in mammalian neocortex development is ongoing.
• Recent progress in understanding cortical connection development is reviewed.

Purpose of the Study:

• To review recent progress in the field of environmental influences on nervous system development.
• To distinguish between establishment and maintenance phases of cortical connections.
• To propose a synthetic view of top-down and bottom-up influences on cortical development.

Main Methods:

• Review of recent scientific literature.
• Distinguishing between systems-level phases of cortical connection development.
• Cellular-level analysis of molecular contributions to cortical plasticity.

Main Results:

• Cortical connection development involves an "establishment" phase (activity-dependent/independent) and a "maintenance" phase (activity-dependent).
• Emergence of orientation selectivity in visual cortex illustrates top-down vs. bottom-up influences.
• NMDA receptors, neurotrophins, and other molecules mediate activity-dependent cortical rearrangement during critical periods.

Conclusions:

• Neuronal activity plays a critical role in the maintenance phase of cortical connections.
• Reciprocal thalamo-cortical projections are key in processes like orientation selectivity development.
• Molecular mechanisms underpin activity-dependent cortical plasticity during specific developmental windows.