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3D GIF Shows How the Human Brain Folds During Development

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Have you ever looked at a picture or illustration of a human brain and wondered why there are so many wrinkles? Researchers have previously found that the folds are a result of the rate at which the brain's gray matter grows, as well as its thickness. Now, in a new study published in Nature Physics, scientists demonstrate how the folds develop using a 3D gel model of a fetal brain based on MRI scans. 

According to the study, folding begins in human brains around the 20th week of gestation and continues until the child is around a-year-and-a-half old. By coating and immersing the 3D gel model of a smooth brain in a solvent, the researchers at Harvard's John A. Paulson School of Engineering and Applied Sciences, in collaboration with scientists in France and Finland, were able to mimic the folding that occurs as the cortex, or outer layer of the brain, expands.

As shown in the timelapse GIF above, the solvent causes the surface of the brain to swell as it absorbs the liquid and to form folds similar in size and shape to those on a real fetal brain. The researchers say this happens because the swelling—akin to cortical expansion—causes compression, which leads to a "mechanical instability" similar to buckling. This mechanical instability causes the folds.

"I knew there should be folding, but I never expected that kind of close pattern compared to human brain," co-author Jun Young Chung said of the model, which has the "same large scale geometry and curvature" of a real brain. "Our research shows that if a part of the brain does not grow properly, or if the global geometry is disrupted, we may not have the major folds in the right place, which may cause potential dysfunction."

Image credit: Mahadevan Lab/Harvard SEAS

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26 Facts About LEGO Bricks

Since it first added plastic, interlocking bricks to its lineup, the Danish toy company LEGO (from the words Leg Godt for “play well”) has inspired builders of all ages to bring their most imaginative designs to life. Sets have ranged in size from scenes that can be assembled in a few minutes to 5000-piece behemoths depicting famous landmarks. And tinkerers aren’t limited to the sets they find in stores. One of the largest LEGO creations was a life-sized home in the UK that required 3.2 million tiny bricks to construct.

In this episode of the List Show, John Green lays out 26 playful facts about one of the world’s most beloved toy brands. To hear about the LEGO black market, the vault containing every LEGO set ever released, and more, check out the video above then subscribe to our YouTube channel to stay up-to-date with the latest flossy content.

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Of Buckeyes and Butternuts: 29 States With Weird Nicknames for Their Residents
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Tracing a word’s origin and evolution can yield fascinating historical insights—and the weird nicknames used in some states to describe their residents are no exception. In the Mental Floss video above, host John Green explains the probable etymologies of 29 monikers that describe inhabitants of certain states across the country.

Some of these nicknames, like “Hoosiers” and “Arkies” (which denote residents of Indiana and Arkansas, respectively) may have slightly offensive connotations, while others—including "Buckeyes," "Jayhawks," "Butternuts," and "Tar Heels"—evoke the military histories of Ohio, Kansas, Tennessee, and North Carolina. And a few, like “Muskrats” and “Sourdoughs,” are even inspired by early foods eaten in Delaware and Alaska. ("Goober-grabber" sounds goofier, but it at least refers to peanuts, which are a common crop in Georgia, as well as North Carolina and Arkansas.)

Learn more fascinating facts about states' nicknames for their residents by watching the video above.

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