High-resolution intersubject averaging and a coordinate system for the cortical surface

TLDR

The human cerebral cortex is a highly folded sheet with most surface area buried in folds, yet cortical maps are usually localized using 3‑D stereotaxic coordinates instead of positions relative to the 2‑D cortical sheet. The study aims to create a surface‑based coordinate system by generating an average cortical folding pattern on the unit sphere and nonrigidly aligning individual subjects to it. The authors generate an average folding pattern across many subjects on the unit sphere and nonrigidly align each individual cortical surface to this average. The resulting spherical surface‑based coordinate system, adapted to each subject’s folding pattern, improves localization accuracy of structural and functional brain features. © 1999 Wiley‑Liss, Inc., Brain Mapping 8:272–284.

Abstract

The neurons of the human cerebral cortex are arranged in a highly folded sheet, with the majority of the cortical surface area buried in folds. Cortical maps are typically arranged with a topography oriented parallel to the cortical surface. Despite this unambiguous sheetlike geometry, the most commonly used coordinate systems for localizing cortical features are based on 3-D stereotaxic coordinates rather than on position relative to the 2-D cortical sheet. In order to address the need for a more natural surface-based coordinate system for the cortex, we have developed a means for generating an average folding pattern across a large number of individual subjects as a function on the unit sphere and of nonrigidly aligning each individual with the average. This establishes a spherical surface-based coordinate system that is adapted to the folding pattern of each individual subject, allowing for much higher localization accuracy of structural and functional features of the human brain. Hum. Brain Mapping 8:272–284, 1999. © 1999 Wiley-Liss, Inc.