A Dynamic Skull Model for Simulation of Cerebral Cortex Folding

Razavi

et al. 2016

Sci Rep

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As a significant type of cerebral cortical convolution pattern, the gyrus is widely preserved across species. Although many hypotheses have been proposed to study the underlying mechanisms of gyrus formation, it is currently still far from clear which factors contribute to the regulation of consistent gyrus formation. In this paper, we employ a joint analysis scheme of experimental data and computational modeling to investigate the fundamental mechanism of gyrus formation. Experimental data on mature human brains and fetal brains show that thicker cortices are consistently found in gyral regions and gyral cortices have higher growth rates. We hypothesize that gyral convolution patterns might stem from heterogeneous regional growth in the cortex. Our computational simulations show that gyral convex patterns may occur in locations where the cortical plate grows faster than the cortex of the brain. Global differential growth can only produce a random gyrification pattern, but it cannot guarantee gyrus formation at certain locations. Based on extensive computational modeling and simulations, it is suggested that a special area in the cerebral cortex with a relatively faster growth speed could consistently engender gyri.

mentioning

confidence: 99%

Mechanism of Consistent Gyrus Formation: an Experimental and Computational Study

Razavi

et al. 2016

Sci Rep

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“…In a real brain, the depth of sulci can vary, while the distance of the gyri from the center remains relatively consistent. We speculate that the same radial distance of gyri in a real brain arises from the constraint of cerebrospinal fluid pressure 41 and the skull 109 . It has been shown that the skull flattens the crest line of gyri 109 .…”

Section: Discussionmentioning

confidence: 89%

Mechanical hierarchy in the formation and modulation of cortical folding patterns

Chavoshnejad

Vallejo

et al. 2023

Sci Rep

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The important mechanical parameters and their hierarchy in the growth and folding of the human brain have not been thoroughly understood. In this study, we developed a multiscale mechanical model to investigate how the interplay between initial geometrical undulations, differential tangential growth in the cortical plate, and axonal connectivity form and regulate the folding patterns of the human brain in a hierarchical order. To do so, different growth scenarios with bilayer spherical models that features initial undulations on the cortex and uniform or heterogeneous distribution of axonal fibers in the white matter were developed, statistically analyzed, and validated by the imaging observations. The results showed that the differential tangential growth is the inducer of cortical folding, and in a hierarchal order, high-amplitude initial undulations on the surface and axonal fibers in the substrate regulate the folding patterns and determine the location of gyri and sulci. The locations with dense axonal fibers after folding settle in gyri rather than sulci. The statistical results also indicated that there is a strong correlation between the location of positive (outward) and negative (inward) initial undulations and the locations of gyri and sulci after folding, respectively. In addition, the locations of 3-hinge gyral folds are strongly correlated with the initial positive undulations and locations of dense axonal fibers. As another finding, it was revealed that there is a correlation between the density of axonal fibers and local gyrification index, which has been observed in imaging studies but not yet fundamentally explained. This study is the first step in understanding the linkage between abnormal gyrification (surface morphology) and disruption in connectivity that has been observed in some brain disorders such as Autism Spectrum Disorder. Moreover, the findings of the study directly contribute to the concept of the regularity and variability of folding patterns in individual human brains.

“…Compared with the later secondary and tertiary folding patterns, primary folding is particularly better preserved among individuals (Armstrong et al, 1995; Chi et al, 1977; Toro & Burnod, 2005; Lohmann et al 2008, Garel et al, 2001; Gilles et al 2013). Many hypotheses have been proposed to explore the mechanisms of primary folding, such as cranial constraint (Clark 1945; Chen et al 2010; Nie et al 2010), axon maturation (Van Essen 1997; Holland et al 2015; Zhang et al 2017; Zhang et al 2016b), and differential growth at the cellular level (Richman 1975; Bayly et al 2013; Ronan et al 2014; Tallinen et al 2014; Razavi et al 2015; Tallinen et al 2016). However, the mechanisms of secondary and tertiary folding remain largely unknown, which stimulates researchers from different disciplines to decipher the mechanisms of such complex morphogenesis.…”

Section: Introductionmentioning

confidence: 99%

“…Compared with the later secondary and tertiary folding patterns, primary folding is particularly better preserved among individuals (Armstrong et al, 1995;Chi et al, 1977;Toro, & Burnod, 2005;Lohmann et al, 2008, Garel et al, 2001Gilles et al, 2013). Many hypotheses have been proposed to explore the mechanisms of primary folding, such as cranial constraint (Chen et al, 2010;Clark, 1945;Nie et al, 2010), axon maturation (Holland et al, 2015;Van Essen, 1997;Zhang et al, 2016bZhang et al, , 2017, and differential growth at the cellular level (Bayly et al, 2013;Razavi et al, 2015;Richman et al, 1975;Ronan et al, 2014;Tallinen et al, 2014;Tallinen et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Exploring 3‐hinge gyral folding patterns among HCP Q3 868 human subjects

Chen

Razavi

et al. 2018

Human Brain Mapping

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Comparison and integration of neuroimaging data from different brains and populations are fundamental in neuroscience. Over the past decades, the neuroimaging field has largely depended on image registration to compare and integrate neuroimaging data from individuals in a common reference space, with a basic assumption that the brains are similar. However, the intrinsic neuroanatomical complexity and huge interindividual cortical folding variation remain underexplored. Here we focus on a specific cortical convolution pattern, termed 3-hinge gyral folding, which is the conjunction of gyri from multiple orientations and has unique and consistent anatomically, structurally, and functionally connective patterns across subjects. By developing a novel shape descriptor and a two-stage clustering pipeline, we devise an automatic method to identify 3-hinges in the Human Connectome Project Q3 868 human brains, and further parameterize the complexity of such a pattern and quantify its regularity and variation in terms of 3-hinge number, position, and morphology. Our results not only exhibit the huge interindividual variations, but also reveal regular relationship between gyral hinges and other factors, such as their locations and cortical morphologies. It is found that "line-shape" cortices have relatively more consistent 3-hinge shape pattern distributions, and certain types of 3-hinge patterns favor particular cortical morphologies. In addition, more 3-hinges are found on "line-shape" cortices while their numbers vary more across subjects than those on "non-line-shape" cortices. This study adds new insights into a better understanding of the regularity and variability of human brain anatomy, and their functional aspects.