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Cortical scaling in mammals: a repeating units model
1Department of Biological Structure, University of Washington, Seattle 98195-74201, USA. pwj@u.washington.edu
Journal Fur Hirnforschung
|January 1, 1997
Summary
A new scaling model explains how brain size relates to cortical thickness, surface area, and volume in mammals. This model suggests brain development patterns are consistent across evolutionary and individual growth.
Area of Science:
- Neuroscience
- Comparative Anatomy
- Evolutionary Biology
Background:
- Mammalian brains exhibit significant variation in size and structure.
- Understanding the scaling rules governing brain morphology is crucial for neuroscience and evolutionary studies.
Purpose of the Study:
- To propose a simple scaling model for gyrencephalic mammalian cortices.
- To account for empirical scaling of cortical morphometric variables (thickness, surface area, volume) with brain size.
Main Methods:
- Assumed modular construction of gyrencephalic cortices from repeating units.
- Model posits that both the number and size of cortical units increase with brain size.
- Assumed invariant surface-density of repeating units and consistent brain/unit shape.
Main Results:
- Predicted model exponents for cortical thickness, folded surface area, and volume as a function of cerebral volume are 1/9, 8/9, and 1, respectively.
- These exponents align with diverse phylogenetic and ontogenetic scaling data.
- Suggested that phylogenetic scaling may reflect ontogenetic scaling across adult brain size ranges.
Conclusions:
- The proposed model provides a framework for understanding mammalian cortical scaling.
- The scaling exponents are likely not adaptive in the conventional sense.
- The model is applicable to ontogenetic and phylogenetic scaling patterns.