Most animals have smooth brains. The brains of humans (and a handful of animals we consider pretty intelligent – dolphins, chimps, elephants, pigs) start out smooth in the early days of gestation and get more and more wrinkled through infancy.
A wrinkled brain makes sense - folding means you can have a really big cortex but the different parts of the brain won’t be as far apart. But how do brains become wrinkled? Is it programmed somehow - does some genetic code determine the pattern of folds?
A new study from Harvard says no - its just simple physics. They created a 3D model of a smooth fetal brain and coated it with an elastomer gel “cortex.” When they immersed this brain in a special solution, the gel swelled, mimicking brain growth.
Lo and behold, the brain began to buckle, creating folds similar to size, shape and location of a real brain.
Image credit: Mahadevan Lab/Harvard SEAS