For something that weighs only about three pounds, the human brain has a lot of responsibility. Deep within all those gray folds and creases are the controls for everything you do.

More than a century ago, scientists first mapped the brain as they worked to develop an understanding of each particular region. Early on, the maps were simple: Which part of the brain controlled speech? Which controlled hearing? Having a detailed, accurate guide ensures that studies are using the same points of reference and makes for more efficient, accurate investigations.

Now, however, things are much more intricate. Researchers have just released an incredible new map of the brain, revealing nearly 100 new areas that were previously undiscovered or forgotten. Many experts are calling this a milestone in neuroscience, according to the New York Times. The new map has been published in the journal Nature.

The new map draws on data collected by the Human Connectome Project, which studied 1,200 people using high-powered MRI scanners to understand how brain circuitry works. For the study, the participants' brains were recorded while they laid in the scanner, while they did various math problems and memory tests, and while they listened to stories. Researchers drew boundaries based on where these and previous tests seemed to match. They also looked at anatomical differences, measuring, for example, the amount of myelin — a fatty substance that surrounds some neurons — in different areas of the brain.

brain activity map The red and yellow areas of the brain show activation, while the blue and green show deactivation. This is the brain of a participant listening to stories in an MRI scanner. (Photo: Matthew F. Glasser, David C. Van Essen)

“We have 112 different types of information we can tap into,” study co-author David Van Essen of Washington University Medical School told the New York Times.

With all those variables in hand, researchers eventually created a map that included 83 already familiar areas of the brain, plus an additional 97 regions that were either previously undiscovered, or somehow forgotten and lost in scientific literature along the way. Some previously known regions are now broken down into subregions with separate responsibilities. For example, the dorsolateral prefontal cortex is a large area toward the front of the brain that's active during thought. The new map shows that it's made up of many smaller areas that can be key for different kinds of thought, ranging from making decisions to lying.

While experts are lauding the new map, it's far from complete, say the researchers who created it.

“We’re thinking of this as version 1.0,” says lead author Matthew Glasser, a neuroscientist at Washington University School of Medicine. “That doesn’t mean it’s the final version, but it’s a far better map than the ones we’ve had before.”

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.