Folding Mechanisms of Cerebral Cortex characterized

Claus Hilgetag, Professor of Neuroscience at IUB, and his colleague Helen Barbas, Professor of Health Sciences at Boston University, found new answers to one of the oldest questions in neuroscience: How do the characteristic folds of the primate brain cortex form? The results of an extensive analysis of neuroanatomic data are published as the cover story in the latest issue of PLoS Computational Biology ("Role of Mechanical Factors in the Morphology of the Primate Cerebral Cortex", Volume 2 | Issue 3 | MARCH 2006, www.ploscompbiol.org).

[ Mar 27, 2006]  By analyzing quantitative data collected in the lab of Helen Barbas over a period of two decades, Claus Hilgetag for the first time was able to provide empirical evidence for the hypothesis that the characteristic folds of the primate brain are mainly formed by mechanical forces of fiber tension. The tension originates from nerve fibers connecting different surface regions of the brain. Strongly interconnected areas are pulled together to form the hills of the brain landscape, while less interconnected areas, subject to less fiber tension, form the valleys between the hills. Furthermore, as the brain expands its surface during its development before and after birth, the cortex folding influences other mechanical forces, such as tissue friction. These, in turn, may affect the passage of new neurons into different regions, thus having an impact on the subsequent development of the brain's architecture, for instance, cortex thickness.

These findings underscore the importance of mechanical forces in shaping the normal brain. Moreover, the findings suggest that pathological changes in brain shape, such as observed in schizophrenia and autism, may result from changes or interferences during the development of the nerve connections.