The intrinsic geometry of the cerebral cortex

Area of Science:

• Neuroscience
• Differential Geometry
• Evolutionary Biology

Background:

• The mammalian cerebral cortex is a six-layered surface that expands with evolution.
• Cortical area increases nearly linearly with cortical volume, unlike geometric predictions.
• Brain size correlates with surface folding (lissencephaly vs. gyrencephaly).

Purpose of the Study:

• To investigate the geometric properties of the mammalian cerebral cortex.
• To determine if the cortex can be accurately modeled using differential geometry.
• To explore the implications of cortical geometry on brain function and development.

Main Methods:

• Reconstruction of a cortical surface from cross-sections.
• Application of differential geometry techniques to analyze intrinsic and extrinsic properties.
• Theoretical considerations and simulations of cortical geometry's effects.

Main Results:

• The cerebral cortex exhibits significant intrinsic curvature, refuting the 'crumpled bag' model.
• Cortical geometry results in functional areas being closely situated.
• Simulations suggest intrinsic geometry influences cortical development, integrative area location, and neuronal firing synchronization.

Conclusions:

• The cerebral cortex is not merely a folded surface but possesses significant intrinsic geometric properties.
• Intrinsic geometric descriptions may be more suitable for understanding the cortex than extrinsic ones.
• Cortical geometry plays a crucial role in brain development and function.