An Integrated Software Suite for Surface-based Analyses of Cerebral Cortex
- Affiliation of the authors: Washington University School of Medicine, St. Louis, Missouri
- Correspondence and reprints: David C. Van Essen, PhD, Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 Euclid Avenue, St. Louis, MO 63110; e-mail: < >
- Received 16 March 2001
- Accepted 8 May 2001
The cerebral cortex is the dominant structure of the mammalian brain and is responsible for an impressively diverse range of sensory, motor, and cognitive functions. Anatomically, the cortex is a sheet-like structure whose surface area greatly exceeds the surface area of a smooth, solid shape containing it. In large-brained mammals, including humans, the cortex is extensively folded, and the pattern of convolutions varies considerably from one individual to the next. The irregularity and variability of these convolutions pose major challenges in analyzing and visualizing cortical structure, function, and development. These problems are particularly acute in view of the explosion of high-resolution data derived from many different experimental methods, particularly non-invasive neuroimaging methods such as structural and functional magnetic resonance imaging (MRI) applied to human beings and nonhuman primates.
Computational cortical cartography represents a powerful general approach to dealing with these problems by using surface-based visualization and analysis methods. The essence of the approach is to represent the cortex by explicit surface reconstructions onto which various types of experimental information are mapped. The advantages of surface reconstructions can be grouped into four main categories:
Visualization using multiple configurations. Once generated, surface reconstructions can be manipulated in shape to improve visualization. Commonly used configurations, besides the initial (fiducial) three-dimensional shape of the cortex, include inflated (extensively smoothed) surfaces, spherical surfaces (used for surface-based coordinates, as discussed below), and flat maps, which allow the entire hemisphere to be viewed with only modest distortions, albeit at the price of artificial cuts (akin to those used in maps of the earth's surface).
Localization using surface-based coordinates. It is often important to be precise about exact locations in the cortex. Surface-based coordinates (latitude and longitude on a sphere) provide a concise, precise, and objective metric that respects the topology of the cortical surface. In this respect, …