Cortical Folding Pattern and its Consistency Induced by Biological Growth

Abstract

Cortical folding, characterized by convex gyri and concave sulci, has an intrinsic relationship to the brain’s functional organization. Understanding the mechanism of the brain’s convoluted patterns can provide useful clues into normal and pathological brain function. In this paper, the cortical folding phenomenon is interpreted both analytically and computationally, and, in some cases, the findings are validated with experimental observations. The living human brain is modeled as a soft structure with a growing outer cortex and inner core to investigate its developmental mechanism. Analytical interpretations of differential growth of the brain model provide preliminary insight into critical growth ratios for instability and crease formation of the developing brain. Since the analytical approach cannot predict the evolution of cortical complex convolution after instability, non-linear finite element models are employed to study the crease formation and secondary morphological folds of the developing brain. Results demonstrate that the growth ratio of the cortex to core of the brain, the initial thickness, and material properties of both cortex and core have great impacts on the morphological patterns of the developing brain. Lastly, we discuss why cortical folding is highly correlated and consistent by presenting an intriguing gyri-sulci formation comparison.

Mechanism of Consistent Gyrus Formation: an Experimental and Computational Study

“…The dimension of the model is 300 × 300 × 50  mm and the thickness of the cortex is 2  mm before growth. Growth in the model is simulated via thermal expansion233562. For understanding the detail of analogy between volumetric growth model and thermal stress model please check reference62.…”

“…Recent 2D and 3D FE models have been designed and implemented to elucidate the role of mechanical parameters during brain development2331. Interestingly, results show that morphological abnormalities related to the developing brain can be presented by mechanical models3435. In a recent study, considerable advancement has been made with respect to the modeling of the morphological evolution of the developing brain, but many questions remain unanswered which beg for further analytical, computational, and experimental investigations.…”

“…S1(a)). The top layer represents the developing cortical plate (cortex) and the bottom layer is the core of the brain which is considered as a simple organization of the subplate, intermediate zone, and ventricular zone35. The Dynamic-Explicit solver in the ABAQUS software is implemented to perform morphological evolution of the growing brain.…”

Is bigger always better? The importance of cortical configuration with respect to cognitive ability

“…Both size and changes in SA and CT are important for brain morphology as suggested by recent work on the mechanisms behind cortical folding patterns (Tallinen et al 2014; Razavi et al 2015). Moreover, cortical stretching suggests that SA and CT are inversely related in some regions (Hogstrom et al, 2013).…”

“…This phenomenon is seen throughout adulthood (Hogstrom, Westlye, Walhovd, & Fjell, 2013) and is most pronounced in some prefrontal regions (Hogstrom et al 2013; Panizzon et al, 2009); also when looking at the relative SA and CT (Winkler et al, 2010). Further evidence for the importance of looking at both relative SA and relative CT comes from studies of gyrification (Tallinen, Chung, Biggins & Mahadevan, 2014; Razavi, Zhang, Liu & Wang, 2015). Gyrification of the cortex, an important characteristic of the human brain, is positively correlated with SA but negatively with CT (Hogstrom et al, 2013).…”