e! Science NewsPublication in Nature showcases most comprehensive wiring diagram of the mammalian brain to date
Published: Wednesday, April 2, 2014 - 21:53 in Biology & Nature
Researchers from the Allen Institute for Brain Science have published the first comprehensive, large-scale data set on how the brain of a mammal is wired, providing a groundbreaking data resource and fresh insights into how the nervous system processes information. Their landmark paper in this week's issue of the journal Nature both describes the publicly available Allen Mouse Brain Connectivity Atlas, and demonstrates the exciting knowledge that can be gleaned from this valuable resource. "Understanding how the brain is wired is among the most crucial steps to understanding how the brain encodes information," explains Hongkui Zeng, Senior Director of Research Science at the Allen Institute for Brain Science. "The Allen Mouse Brain Connectivity Atlas is a standardized, quantitative, and comprehensive resource that will stimulate exciting investigations around the entire neuroscience community, and from which we have already gleaned unprecedented details into how structures are connected inside the brain."
Using the data, Allen Institute scientists were able to demonstrate that there are highly specific patterns in the connections among different brain regions, and that the strengths of these connections vary with greater than five orders of magnitudes, balancing a small number of strong connections with a large number of weak connections. This publication comes just as the research team wraps up more than four years of work to collect and make publicly available the data behind the Allen Mouse Brain Connectivity Atlas project, with the completion of the Atlas announced in March 2014.
Creating a Roadmap for the Brain
The human brain is among the most complex structures in the entire universe, containing roughly 100 billion neurons -- as many stars as are in the Milky Way. The mouse brain's 75 million neurons, arranged in a roughly similar structure to the human brain, provide a powerful model system by which to understand how nerve cells of the human brain connect, process and encode information. Despite the foundational need to understand how areas of the brain are connected, the only species for which we have a complete wiring diagram is the simple microscopic worm C. elegans -- a far simpler system, with only 302 neurons, compared to the human or any other mammalian nervous system.
Scientists at the Allen Institute set out to create a wiring diagram of the brain -- also known as a "connectome" -- to illustrate short and long-range connections using genetically-engineered viruses that could trace and illuminate individual neurons. In order to get a truly comprehensive view, scientists collected imaging data at resolutions smaller than a micrometer from more than 1,700 mouse brains, each of which was divided into 140 serial sections. "The data for the Allen Mouse Brain Connectivity Atlas was collected in a way that's never been done before," says Zeng. "Standardizing the data generation process allowed us to create a 3D common reference space, meaning we could put the data from all of our thousands of experiments next to each other and compare them all in a highly quantitative way at the same time."
The Allen Mouse Brain Connectivity Atlas contains more than 1.8 petabytes of data -- the equivalent of 23.9 years of continuous HD video -- all of which is freely available online to the entire community. The research team behind the Atlas has been steadily releasing new data since November 2011; and in March, they released the last major update to the Atlas, though the resource will continue to be updated as technology develops and researchers are able to add more new types of connectivity data. Like all of the Allen Brain Atlas resources, the data and the tools to browse and analyze them are freely available to the public at http://www.brain-map.org
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