Department of Mathematics Colloquium
University of Michigan
Ann Arbor, MI
December 4, 2001

Discrete Conformal Flattening of the Human Brain Using Circle Packing

Monica K. Hurdal, Department of Mathematics, Florida State University

The human brain is composed of many folds and fissures which vary considerably in their size and extent between individuals. It is also known that most of the functional processing occurs on the surface of the brain in the grey matter, of which 60-70% is hidden from view as it is buried in the folds. This individual variability makes it very difficult to compare different brains across subjects. As a result, there is great interest amongst neuroscientists to unfold and flatten the cortical surface, with the aim of comparing brain maps across individuals. It is impossible to preserve linear or areal information when flattening a surface with intrinsic curvature such as the brain. However, it is possible to preserve conformal information. I will discuss a method which uses circle packings to compute a discrete approximation of the conformal map of a surface embedded in 3-space. I will present results of some of the maps I have created of the brain and discuss some of the topological and computational problems that arise.


Updated November 2001.
Copyright 2001 by Monica K. Hurdal. All rights reserved.