A model of tension-induced fiber growth predicts white matter organization during brain folding

The past decade has experienced renewed interest in the physical processes that fold the developing cerebral cortex. Biomechanical models and experiments suggest that growth of the cortex, outpacing growth of underlying subcortical tissue (prospective white matter), is sufficient to induce folding. However, current models do not explain the well-established links between white matter organization and fold morphology, nor do they consider subcortical remodeling that occurs during the period of folding. Here we propose a framework by which cortical folding may induce subcortical fiber growth and organization. Simulations incorporating stress-induced fiber elongation indicate that subcortical stresses resulting from folding are sufficient to induce stereotyped fiber organization beneath gyri and sulci. Model predictions are supported by high-resolution ex vivo diffusion tensor imaging of the developing rhesus macaque brain. Together, results provide support for the theory of cortical growth-induced folding and indicate that mechanical feedback plays a significant role in brain connectivity. Associations have been established between brain folding and white matter connectivity. Here the authors show that axon elongation, in response to mechanical stresses during cortical expansion and folding, may be sufficient to induce tissue remodeling consistent with white matter organization.

Automated summary

The article discusses a new theoretical framework regarding the physical processes of cerebral cortex folding, proposing that cortical folding may induce subcortical fiber growth and organization. Through simulations and experiments, it is demonstrated that subcortical stresses resulting from folding are sufficient to induce stereotyped fiber organization beneath gyri and sulci, supporting the viewpoint of cortical growth-induced folding.