Architectonic Brain Mapping
Cytoarchitectonic probability maps
Neuroscientist Prof. Dr. Katrin Amunts and her team go on a unique research expedition to create a three-dimensional atlas of the brain.
At first glance, the “route” is limited. The human brain contains about 1,500 cm³ of brain tissue, and the terrain is quite something. The goal “is to develop a realistic, three-dimensional computer brain model based on structural, cytoarchitectonic, genetic, and molecular characteristics.” As part of this project, scientists at INM-1 are examining many thousands of histological brain sections. The sections are analyzed using modern scanning microscopes and image analysis methods. Then the cellular architecture are statistically analyzed and digitally reconstructed in 3-D. With her colleague, Prof. Dr. Karl Zilles, and a large team of medical doctors, physicists, biologists, mathematicians and graduate students, Prof. Dr. Katrin Amunts is developing a unique brain atlas that will gradually replace Brodmann’s map from 1909. “The psychiatrist and anatomist Korbinian Brodmann mapped the cerebral cortex and divided it into about 50 areas. He not only created a cytoarchitectonic map, but also provided the basis for later comparative neuroanatomical investigations. Brodmann was convinced that each brain area is responsible for a specific function, an assumption that could only be proven for a small fraction of the areas with the resources available at that time,” [K. Amunts, director of the Institute of Neuroscience and Medicine (INM-1) at Forschungszentrum Jülich, and professor of structural-functional brain mapping at the Department of Psychiatry and Psychotherapy at RWTH Aachen University.Klinik für Psychiatrie, Psychotherapie und Psychosomatik]
Although Brodmann’s discovery was groundbreaking, the hundredyear- old map is merely a schematic drawing, not the three-dimensional record that is needed today as a basis for comparison in modern imaging studies to assign patient data to the microscopic structures of the brain. “We need to understand the ‘healthy’ brain before we can take the next step and distinguish differences in people suffering from neurological or psychiatric disorders,” explains Katrin Amunts. Although only about 70 percent of the brain is mapped, the 3-D model from Jülich is already more complex than the Brodmann map. There are several reasons for this: Katrin Amunts and her interdisciplinary team analyze inter-individual differences in brain structure, then register their inter- individual variability; they not only map the cerebral cortex, but also nuclei deep in the brain. “The areas of the cortex do not operate in isolation like islands. Rather, they form networks and cooperate with the subcortical nuclei,” she explains. The 3-D brain model continues to develop with each newly defined area. The procedure is very time-consuming, as a scientist needs about a year to analyze and map a new area.
About 70 percent of the brain has now been mapped. Thousands of histological brain sections have been, and are being, investigated at Forschungszentrum Jülich. The tissue samples are scanned using microscopes and advanced image analysis techniques. They are then statistically analyzed and reconstructed on a computer in 3-D.