GPS for the brain? New brain atlas wows scientists

It's being called the world's first "anatomically and genomically comprehensive" map of the human brain - a sort of "GPS for the brain" designed to speed research into brain disorders ranging from mental illness to Alzheimer's and Parkinson's diseases, autism, multiple sclerosis, and more. It is the Allen Human Brain Atlas, a detailed, three-dimensional online atlas of the brain that's just making its debut. "Until now, a definitive map of the human brain, at this level of detail, simply hasn't existed," the CEO of the Allen Institute for Brain Science, Dr. Allan Jones, said in a written statement, adding that the atlas gives "never-before-seen views into our most complex and most important organ."

Keep clicking to see incredible images from the atlas, along with photos showing how the atlas was created...

The brain map - created using data from two normal adult human brains - lets scientists see exactly where various genes are "expressed" in the brain. The stripes show gene expression in the the cortex (the brain's outer portion), while the dots (mostly hidden) show gene expression in the inner regions of the brain. Red means high gene activity, while green means lower activity.

This three-dimensional rendering from the atlas shows areas deep within the brain where the gene that controls a protein targeted by the antidepressant Prozac is active.

In this slab of brain tissue sliced from one half of the brain, dark areas are packed with brain cells, while the light areas are bundles of nerve fibers that connect different regions of the brain.

Here, a researcher measures a frozen slab of brain tissue. Each slab is numbered and bar-coded for reference before additional processing can take place.

Here, a frozen brain section about one centimeter thick has been "annotated" with blue dots to keep track of the brain's front-to-back orientation as the brain is further subdivided. After this step, the section is cut into thinner slices.

This brain section has been treated with a silver stain to highlight key anatomic information. Light areas show the brain's outer layer, or cortex, which is packed with nerve cells. Dark regions show nerve fibers that connect different areas of the brain.

Each section of brain is put on a special cutting machine known as a microtome and sliced into sections thinner than a human hair.

Here, a frozen slab of brain tissue is being prepared for slicing. It's tricky work, as the brain has to be sliced thinner than a human hair.

Once the brain has been sliced wafer-thin, each section is placed on a slide for analysis using a microscope.

Here's a thin section of brain treated to show the fine anatomic details. The pink color comes from a "neuropathological" stain.