Gyral net: A new representation of cortical folding organization

Abstract

One distinct feature of the cerebral cortex is its convex (gyri) and concave (sulci) folding patterns. Due to the remarkable complexity and variability of gyral/sulcal shapes, it has been challenging to quantitatively model their organization patterns. Inspired by the observation that the lines of gyral crests can form a connected graph on each brain hemisphere, we propose a new representation of cortical gyri/sulci organization pattern – gyral net, which models cortical architecture from a graph perspective, starting with nodes and edges obtained from the reconstructed cortical surfaces. A novel computational framework is developed to efficiently and automatically construct gyral nets from surface meshes, and four measurements are devised to quantify the folding patterns. Using an MRI dataset for autism study as a test bed, we identified reduced local connectivity cost and increased curviness of gyral net bilaterally on the parietal lobe, occipital lobe, and temporal lobe in autistic patients. Additionally, we found that the cortical thickness and the gyral straightness of gyral joints are higher than the rest of gyral crest regions. The proposed representation offers a new tool for a comprehensive and reliable characterization of the cortical folding organization. This novel computational framework will enable large-scale analyses of cortical folding patterns in the future.

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

“…Besides the morphologies of lobes and gyro-sulcal patterns, other factors could have a close relationship with 3-hinge numbers and shape patterns. For example, in one of our recent studies (Ge et al, 2017), denser dMRI derived fiber connections were found in 3-hinges than other gyral regions. Such a relationship leads to a hypothesis that axonal growth might play a role in 3-hinge formation.…”

“…The locations and the morphological skeletons of 3-hinges were extracted based on our recently developed automatic pipeline (Chen et al 2017), which is illustrated in Figure 2. To make the manuscript self-contained, we present a summarized version of this pipeline.…”

“…Generally, gyral skeletons are the crest curves located in the central parts of gyri, which are the furthest locations on gyral regions from the borders between gyral crests and sulcal basins. The method detailed in (Chen et al 2017) are an enhanced version of the one in (Li et al 2010a). First, distance transform was conducted on the segmented gyral area to highlight the center of gyral crest.…”

“…In response, we recently developed an automatic data processing and analysis pipeline that is capable of handling big datasets to extract 3-hinges gyri based on a ‘gyral net’ system (Chen et al 2017). With the availability of hundreds of thousands of automatically extracted 3-hinges in many different brains, the objective of this work is to devise novel morphological features to depict and parameterize those 3-hinges’ morphologies, and design a pipeline to group them to clusters.…”

“…In fact, 3-hinges are of unique structural and functional importance in terms of structural and functional features, brain development, and brain evolution, and has the potential to determine intersubject correspondence (Chen et al, 2014;Ge et al, 2017;Jiang et al, 2015Jiang et al, , 2016aJiang et al, , 2016bLi, et al, 2010;Nie et al, 2012;Yu et al, 2013;Zhang et al, 2014). In our previous works (Supporting Information, Figure S7 and Table S3), it has been demonstrated that 3hinges have thicker cortices , higher fiber density and diversities (Chen et al, 2014;Ge et al, 2017;Li et al, 2010;Yu et al, 2013), and are more strongly functionally connected (Jiang et al, 2015(Jiang et al, , 2016a(Jiang et al, , 2016b compared to other gyral regions.…”