Mechanics of cortical folding

Many studies have shown that knowledge of cortical folding is key to interpreting the normal development of the human brain during the early stages of growth. Cognitive or physiological difficulties and problems, e.g. epilepsy, retardation, autism and schizophrenia, are consequences of abnormal cortical folding in the fetal stage fetal stage. In order to discover the underlying mechanisms of the common pattern and structure-function relationship, scientists have long been intrigued and have put forward hypotheses of radial convolution morphogenesis being influenced by multiple possible external/internal causes, e.g., cranial constraint, differential growth on cellular bases, or axon maturation. Therefore, there is a critical need to explore the fundamental mechanical principles of normal cortical folding and provide novel diagnostics and treatments of neurological disorders during early brain development.

growing brain with different cortex thickness ratio
Morphological evolution of the growing model with different thickness of cortex.

 

Three hinges patterns
First row: Three examples of three hinges on convoluted models; second row: similar gyral folding patterns on white matter surface in real brains.

The living human brain is modeled with a soft structure having outer cortex and inner core to investigate the brain development. Analytical interpretations of differential growth of the brain model provide preliminary insight into the critical growth ratio for instability and crease formation of the developing brain followed by computational modeling as a way to offer clues for brain’s postbuckling morphology. Especially, tissue geometry, growth ratio, and material properties of the cortex are explored as the most determinant parameters to control the morphogenesis of a growing brain model. As indicated in results, compressive residual stresses caused by the sufficient growth trigger instability and the brain forms highly convoluted patterns wherein its gyrification degree is specified with the cortex thickness. Morphological patterns of the developing brain predicted from the computational modeling are consistent with our neuroimaging observations, thereby clarifying, in part, the reason of some classical malformation in a developing brain.

3-hinges procedure
Bigdata procedure of 3-hinges formation in human brain.

Publications

M. J. Razavi, T. Zhang, T. Liu and X. Wang, "Cortical Folding Pattern and its Consistency Induced by Biological Growth", Scientific Reports, 5: 14477, 2015.

M. J. Razavi, T. Zhang, X. Li, T. Liu and X. Wang, "Role of Mechanical Factors in Cortical Folding Development", Physical Review E, 92: 320701, 2015.

Collaborators

Dr. Tianming Liu (UGA Department of Computer Science)