Morphogenesis and morphometry of brain folding patterns across species.

Area of Science:

• Neuroscience
• Developmental Biology
• Biophysics

Background:

• Cortical folding (gyrification) is a hallmark of mammalian brain evolution, linked to advanced cognitive abilities.
• The complex folding patterns of the mammalian cortex arise during early development, with variations across species suggesting underlying principles.
• Understanding the mechanisms of cortical folding is crucial for comprehending brain evolution and function.

Purpose of the Study:

• To investigate the biophysical mechanisms driving cortical folding across different mammalian species.
• To compare folding patterns generated through physical models, computational simulations, and in vivo observations.
• To determine if differential growth alone can explain the observed variations in cortical gyrification.

Main Methods:

• Construction of two-layer physical gel brain models that swell to mimic cortical expansion and folding.
• Development of a three-dimensional continuum model simulating cortical folding via differential growth in silico.
• Comparative geometric morphometric analysis of surface buckling patterns from in vivo, in vitro, and in silico models.

Main Results:

• Physical gel models successfully replicated in vivo cortical folding patterns observed in ferret, macaque, and human brains.
• Computational simulations demonstrated that differential growth is a sufficient mechanism to induce cortical folding.
• Variations in tangential growth rates and initial geometric configurations explained species-specific differences in cortical folding.

Conclusions:

• Cortical folding is a mechanical process primarily driven by differential growth and resulting instabilities.
• The diversity of mammalian cortical folding patterns can be explained by variations in growth dynamics and initial brain geometry.
• This study provides a unified mechanical framework for understanding cortical gyrification across species.