Researchers have created the first large-scale data set that gives an in-depth look at the wiring of a mouse's brain; helping gain insight into how the nervous system processes information.

"Understanding how the brain is wired is among the most crucial steps to understanding how the brain encodes information," Hongkui Zeng, Senior Director of Research Science at the Allen Institute for Brain Science said in a news release. "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."

The data shows how the brain has extremely specific patterns of connection in various regions, and these connections "vary with greater than five orders of magnitudes," the news release reported.

The human brain has 100 billion neurons, which is about as many as there are stars in the Milky Way. A mouse's brain only has 75 million neurons, but its structure is similar to a human's and could help scientists gain insight into the mammalian brain. In the past the only fully-mapped brain belonged to the C. elegans worm, which only has 302 neurons.

The researchers worked to create the "connectome" map of the mouse's brain in order to demonstrate "short and long-range connections using genetically-engineered viruses that could trace and illuminate individual neurons," the news release reported.

The researchers gathered image data tinier than a micrometer from the brains of over 1,700 mice.

 "The data for the Allen Mouse Brain Connectivity Atlas was collected in a way that's never been done before," Zeng said. "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 final results can be seen as a "road map" to the mammalian brain.

"The Allen Mouse Brain Connectivity Atlas provides an initial road-map of the brain, at the level of interstate highways and the major cities that they link," David Anderson, Professor of Biology and Howard Hughes Medical Institute Investigator at the California Institute of Technology, said in the news release. "Smaller road networks and their intersections with the interstates will be the next step, followed by maps of local streets in different municipalities. This information will provide a framework for what we ultimately want to understand: 'traffic patterns' of information flow in the brain during various activities such as decision-making, mapping of the physical environment, learning and remembering, and other cognitive or emotional processes."

The map will be an important tool for neuroscientists in the future.

"Who you are-all your thoughts and actions your entire life-is based on connections between neurons," Ed Callaway, Professor in the Systems Neurobiology Laboratories at the Salk Institute for Biological Studies said in the news release. "So if we want to understand any of these processes or how they go wrong in disease, we have to understand how those circuits function. Without an atlas, we couldn't hope to gain that understanding."