New MRI Study Reveals Surprisingly Simple Structure Underlying Complexity of Connections within the Primate Brain

BUSM researchers were part of an international team of investigators to discover a remarkably simple organizational structure in the brains of humans and non-human primates. The researchers found that the brains of higher animals are built from parallel and perpendicular fibers that cross each other in an orderly fashion. According to the researchers this kind of simple organization was completely unsuspected. The findings were reported in the March 30 issue of Science.

Researchers employed sophisticated mathematical analysis of advanced MRI imaging data developed by the lead author, Dr. Van Wedeen of Harvard Medical School, to reveal that fiber pathways carrying neural signals through the brain are arranged in a simple, curved, three-dimensional grid. To verify this, Drs. Douglas L. Rosene and Farzad Mortazavi of the Laboratory for Cognitive Neurobiology at BUSM applied sophisticated immunohistochemical methods to identify the 3D organization of individual nerve fibers using confocal microscopy. Their findings confirmed at a microscopic level, this surprising grid-like structure of parallel and perpendicular fibers.

“Our study demonstrates that all crossing or adjacent fibers are either perpendicular or parallel to the principal axes of the forebrain creating interwoven three-dimensional curved grid structures,” said Doug Rosene, professor of Anatomy and Neurobiology at BUSM. “This is important because we know that there is a simple plan, modified by evolution and development, that gives rise to all brain connections and this should facilitate construction of an atlas of brain connections. Such an atlas would be useful for investigating how the brain develops and how it responds to pathology as well as for expanding theories of how the brain works,” he added.

Additional co-authors of the Science article are Ruopeng Wang and Guangping Dai of the Martinos Center; Patric Hagmann of the University of Lausanne, Switzerland; Jon Kaas of Vanderbilt University in Nashville; and Wen-Yih Tseng of the National Taiwan University College of Medicine. The study was supported by grants from the National Science Foundation and the National Institutes of Health, including the Human Connectome Project.