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Developing Brains Fold Like Crumpled Paper to Get Their Convolutions
A single mathematical function explains how both a sheet of paper and a developing brain folds
By Sabrina Imbler | July 7, 2015


The growing mammalian brain folds just like any sheet of office paper, governed by a single mathematical function.
Suzana & Luiza Herculano-Houzel

A brain and a crisp sheet of office paper may seem to have little in common. But if someone crumples the paper into a ball, they’re holding the solution to one of the most longstanding mysteries of brain development, according to a study published July 2 in Science. As it turns out, the growing mammalian brain folds just like any sheet of office paper, governed by a single mathematical function.

The “brilliant study” represents a significant advance in scientists’ understanding of how the brain develops, says neurologist Arnold Kriegstein of the University of California, San Francisco, who was not part of the study. The research also casts light on the mechanisms behind certain structural disorders of the brain and could inform future efforts to ease those ailments.

Cryptic cortices
The human brain cortex—its outer layer—is an intricately furrowed landscape with ridges called gyri and valleys called sulci. There is a clear advantage to such cortical folding. Having a thinner, folded cortex means ...

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The Problem of Artificial Willpower
The ethical threat posed by Adderall and other drugs that improve motivation
By Hazem Zohny | July 7, 2015


What do we risk by using substances that enhance our enjoyment and interest in certain pursuits – say, a university major or career – which we would otherwise find meaningless and alienating?
Credit: FtWashGuy via Wikimedia Commons

For the avid coffee drinker bound to a monotonous desk job, there is a moment – perhaps two thirds of the way through a cup – when the unbearably tedious task at hand starts to look doable. Interesting, even. Suddenly, data entry is not something that merely pays the rent, it’s something you’re into. A caffeine-triggered surge of adrenaline and dopamine works to enhance your motivation, and the meaninglessness of it all fades as you are absorbed into your computer screen.

At least until the effect wears off. Then it’s time for another caffeine hit. Except, several thousand of those hits later, you find yourself middle-aged and struggling with a sense that you haven’t quite spent your life as you would have liked.

Unlikely as this may sound, it illustrates a reasonable possibility: drugs like caffeine can positively alter ...

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