A video showing the swelling of the brain and the formation of the folds is available on YouTube. (Video credit: Tuomas Tallinen, Jun Young Chung, and L. Mahadevan. Uploaded by NPG Press to YouTube).

A video showing the swelling of the brain and the formation of the folds is available on YouTube. (Video credit: Tuomas Tallinen, Jun Young Chung, and L. Mahadevan. Uploaded by NPG Press to YouTube).

The folds  on the surface of the human brain exist because of physics, not biology, according to a new study using 3D printing. The researchers believe their results suggest that physical forces play a crucial role in neurodevelopment, and may provide insights into diagnosing and treating some neurological disorders.

The study proves a model from 1975, which proposed the brain’s shape is explained as a physical growth process.

Researchers mimicked the development of the human brain by layering different types of gel, designed to swell when immersed. They found mechanical compression forces created the folds.

Original research paper published in Nature Physics on February 1, 2015.

Names and affiliations of selected authors

L. Mahadevan, Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, U.S.A.