Theory: Flexibility is at the heart of human intelligence

Centuries of study have yielded many theories about how the brain gives rise to human intelligence. Some neuroscientists think intelligence springs from a single region or neural network. Others argue that metabolism or the efficiency with which brain cells make use of essential resources are key.

A new theory, published in the journal Trends in Cognitive Sciences, makes the case that the brain's dynamic properties - how it is wired but also how that wiring shifts in response to changing intellectual demands - are the best predictors of intelligence in the human brain.

"When we say that someone is smart, we understand intuitively what that means," said University of Illinois psychology professor Aron Barbey, the author of the new paper. "Usually, we're referring to how good they are at making decisions and solving particular types of problems. But recently in neuroscience, there's been a focus on understanding in biological terms how general intelligence arises." That requires studying the structural and functional characteristics of the brain.