Computerized Mappings of the Cerebral Cortex: A Multiresolution Flattening Method and a Surface-Based Coordinate System

Abstract

We present a new method for generating two-dimensional maps of the cerebral cortex. Our computerized, two-stage flattening method takes as its input any well-defined representation of a surface within the three-dimensional cortex. The first stage rapidly converts this surface to a topologically correct two-dimensional map, without regard for the amount of distortion introduced. The second stage reduces distortions using a multiresolution strategy that makes gross shape changes on a coarsely sampled map and further shape refinements on progressively finer resolution maps. We demonstrate the utility of this approach by creating flat maps of the entire cerebral cortex in the macaque monkey and by displaying various types of experimental data on such maps. We also introduce a surface-based coordinate system that has advantages over conventional stereotaxic coordinates and is relevant to studies of cortical organization in humans as well as non-human primates. Together, these methods provide an improved basis for quantitative studies of individual variability in cortical organization.

CRUISE: Cortical reconstruction using implicit surface evolution

“…Correspondences between cortical reconstructions from different subjects can also be used for image registration (Cachier et al, 2001;Davatzikos, 1997;Hellier and Barillot, 2003;Tao et al, 2002), digital atlas labeling (Jaume et al, 2002;Sandor and Leahy, 1997), and population-based probabilistic atlas generation (Thompson et al, 1997). In addition, cortical reconstruction is important for functional brain mapping (Dale and Sereno, 1993), surgical planning (Grimson et al, 1998), and cortical unfolding or flattening (Carman et al, 1995;Drury et al, 1996;Essen et al, 2001;Fischl et al, 1999a,b;Tosun and Prince, 2001).…”

Volumetric vs. surface-based alignment for localization of auditory cortex activation

“…These methods optimally transform the cortical sheet to a mathematically simpler shape such as a 2D sheet (Drury et al, 1996;Drury et al, 1997;Van Essen et al, 1998;Drury et al, 1999), an ellipsoid (Sereno et al, 1996), or a sphere (Davatzikos, 1996;Toga, 1996, 1998;Fischl et al, 1999;Van Essen, In Press). Van Essen et al (1998) modeled the flattened surface as a viscoelastic fluid sheet (Joshi and Miller, 2000).…”

Cortical surface segmentation and mapping

“…1c shows an example of an original central cortical surface and both a coarse partially flattened map and a spherical map. To obtain a coarser shape and a more regular mesh structure, the central surface mesh is smoothed using the following relaxation operator (Drury et al, 1996) …”

“…For quantitative evaluation, however, it is necessary to establish a coordinate system on the cortex so that features can be identified more rigorously (Angenent et al, 1999;Drury et al, 1996;Fischl et al, 1999;Hurdal et al, 1999;MacDonald et al, 2000;Thompson et al, 2000). Spherical coordinates are appropriate since the topology of the sphere is the same as that of the cortical surface.…”

“…Morphometric measurements such as volume (Kim et al, 2000), surface area (Magnotta et al, 1999), thickness (Kruggel and von Cramon, 2000;Yezzi and Prince, 2003), and sulcal depth (Manceaux-Demiau et al, 1998) can be used to provide valuable information about cortical characteristics in both health and disease. In addition, cortical reconstruction is important for functional brain mapping (Dale and Sereno, 1993), surgical planning (Grimson et al, 1998), and cortical unfolding or flattening (Drury et al, 1996;Fischl et al, 1999).…”