For decades scientists have tried, mostly in vain, to explain where intelligence resides in our brains. The answer, a new study suggests, is everywhere.
After analysing the brain as an incredibly dense network of interconnected points, a team of Dutch scientists has found that the most efficiently wired brains tend to belong to the most intelligent people.
And improving this efficiency with drugs offers a tantalising – though still unproven – means of boosting intelligence, say researchers.
The concept of a networked brain isn’t so different from the transportation grids used by cars and planes, says Martijn van den Heuvel, a neuroscientist at Utrecht University Medical Center who led the new study.
“If you’re flying from New York to Amsterdam, you can do it in a direct flight. It’s much more effective than going from New York, then to Washington, and then to Amsterdam. It’s exactly the same idea in the brain,” he says.
Instead of airports, van den Heuvel’s team mapped the communications between tiny slivers of brain measured by a functional magnetic resonance imaging (fMRI) machine. Rather than scan the brains of subjects performing mental tasks, as most fMRI studies do, researchers took 8-minute-long snapshots of the brains of 19 volunteers, as they did nothing in particular.
The subjects’ brains, of course, didn’t go completely quiet, and the researchers reasoned that any brain activity they measured represented underlying connectivity between brain regions, near and far.
This allowed van den Heuvel’s team to build connectivity networks for each volunteer, and to measure the efficiency of each network. “It more or less reflects how many steps a [brain] region has to take to send information from one region to another,” he says.
This measure proved a decent predictor of each person’s IQ, explaining about 30 per cent of the differences between subjects, van den Heuvel says.
Intriguingly, the researchers found no link between the total number of connections in a subject’s brain network and their IQ. “We show that more intelligent people don’t have more connections, but they have more efficiently placed connections,” he says.