APRIL-MAY 2000

MAPPING THE HUMAN BRAIN

By Jill Elish
FSU Communications Group

Using a 150-year-old mathematical theorem, Florida State University researchers are creating cutting-edge maps of the cerebellum to chart a groundbreaking new course in the study of the human brain.

Monica Hurdal, a postdoctoral research associate of mathematics who is working for FSU Professor DeWitt Sumners, and a team of researchers have developed a one-of-a-kind computer program that can map the human brain in ways never done before. The program is a computer realization of the Riemann Mapping Theorem, which allows a three-dimensional surface to be flattened - while preserving the angular information.

While there are other researchers who are looking at new ways to create maps of the brain, the FSU team is the only group to create conformal brain maps - those that preserve the angles - using information from magnetic resonance imaging (MRI) scans. Other techniques usually display cross-sections of the brain surface, making it difficult to view the entire brain surface at once.

The new method allows researchers to observe the entire surface of the brain, particularly regions buried within cortical folds.

"Everybody's brain is different, like a fingerprint," Hurdal said. "The fissures of the brain vary greatly from person to person, and we think this method will allow scientists to make comparisons that will hopefully lead to a greater understanding of how the brain works. Even though there has been a lot of research, we still know really very little about the brain."

This new way of brain mapping will allow scientists to impose a unique coordinate system on the brain's surface in order to measure and compare brains. The maps can be used to compare anatomical regions of the brain, compare brains from two or more subjects and display data from PET and MRI scans.

"It's a mathematically sound method to create maps that will allow comparison of brain activity to diagnose illness or identify a problem, such as a tumor," she said. "These maps are unique for each person."
In addition to using them as diagnostic tools, Hurdal said doctors may eventually use the maps to help them prepare for brain surgery.

The maps could also help researchers discover how different brains handle the same task or how brains change as people age. The maps may also allow scientists to observe how diseases such as Alzheimer's affect the way the brain functions, she said.

Hurdal is using the computer program to produce maps in a number of different ways. For example, the new maps can be created in the Euclidean plane where distance is measured or scaled as expected, as on a road map.
The program also can be used to create a map using hyperbolic geometry. With these hyperbolic maps, the software can be used to select map points or anatomical landmarks to be the new map center, forcing distortion to the map periphery. In this manner, the map focus can be changed to any desired location, much like moving a magnifying glass over a piece of paper or a microscope over a slide specimen. In addition, the hyperbolic maps are all the same shape - a circle - making it easier to compare different maps from different brains.
Brain maps also can be created on a sphere, which is comparable to viewing the surface of the earth on a globe. Hurdal's maps can be viewed at her Web site: www.math.fsu.edu/~mhurdal.

Hurdal is currently producing flat maps of the brains of some patients suffering from cerebellar ataxia - a disease that involves atrophy of the cerebellum - using data from the PET Imaging Center at the Veterans' Affairs Medical Center at the University of Minnesota.

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