Gyrification and cortical measures

There are a variety of morphometric measures to describe the cortex, such as thickness, area, volume, and curvature.  In our lab,  we focus on local, surface-based methods.

The cortical thickness measure can be applied to studies of Alzheimer’s dementia, schizophrenia, brain development, and aging. The fundamental problem is that there are different approaches to estimating cortical thickness, which produce significantly different results. Thickness measurement methods can be divided into three categories: voxel-, surface- and gradient-based. The estimation of cortical thickness is part of our central surface reconstruction process.

The brain surface in healthy human adults is normally highly convoluted, with ridges (gyri) and faults (sulci). Gyrification refers to both this folding process and quantitative measures thereof. Given that abnormal gyrification patterns have been found in patients with schizophrenia and other neuropsychiatric disorders, we develop methods, based on structural MRI scans, to measure gyrification automatically on both local and whole-brain levels. We hope that these methods may eventually contribute to an earlier diagnosis and for monitoring patients during the therapeutic phase. The gyrification of the the cortex can be measured by curvature, as a relation between different cortical surfaces for the global brain, or as the relation between the curves of these surface in a slice.

The depth of sulci can be measured based on a hull surface which surrounds the whole brain and gives additional information on the convolution of the brain. Like thickness measures, sulcal depth also allows different definitions.