WEDNESDAY, April 13 (HealthDay News) -- The world's first anatomically and genetically detailed map of the human brain has been completed by U.S. scientists, who said their achievement might lead to new treatments for a number of brain diseases.

The team at the Allen Institute for Brain Science used leading-edge technology and took more than four years to complete the project.

The mappings of the biochemistry of two normal adult human brains revealed a 94 percent similarity between human brains, and also showed that at least 82 percent of all human genes are expressed in the brain.

The findings provide the foundation for the Allen Human Brain Atlas, an online public resource available to researchers. The atlas identifies 1,000 anatomical sites in the human brain, along with more than 100 million data points that indicate the particular gene expression and underlying biochemistry of each site.

Researchers will be able to use the atlas in a number of ways, including examining how disease and injury affect specific areas of the brain. They'll also be able to pinpoint where a drug acts in the brain, which could help improve outcomes for a number of therapies.

"Until now, a definitive map of the human brain, at this level of detail, simply hasn't existed," Allan Jones, chief executive officer of the Allen Institute for Brain Science, said in an institute news release.

The atlas "provides never-before-seen views into our most complex and most important organ. Understanding how our genes are used in our brains will help scientists and the medical community better understand and discover new treatments for the full spectrum of brain diseases and disorders, from mental illness and drug addiction, to Alzheimer's and Parkinson's diseases, multiple sclerosis, autism and more," Jones said.

More information

The U.S. National Institute of Neurological Disorders and Stroke has more about the brain.