The Elite Brain Network

Using MRI scans, researchers have found 12 hubs of extraordinarily dense connections in the brain that are all tied together. Now they want to figure out why this special network exists.

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That the brain is a powerful and complex organ is no mystery. But what researchers have begun to discover is that there are select areas of the brain that are so dense in their activity and interconnections that researchers have dubbed them the "rich clubs" of the brain.

A new study used a special type of MRI scan to map out the connections in the brains of 21 men and women. There are regions of the brain in which connectivity is extraordinarily dense -- that's been known for some time. What the present study set out to do was visualize how these dense regions might be connected to one another, possibly forming an elite network between these distinct and powerful regions of the brain.

They found exactly that: Twelve discrete hubs in the brain were interconnected with one another across hemispheres, forming what the researchers call a "rich club," distinct from the regular or "lower" network of the brain.

The work was carried out at Indiana University and at the Rudolf Magnus Institute of Neuroscience in the Netherlands. Author Olaf Sporns says that his team's findings show that "these regions are not only individually rich, they are forming a 'rich club.' They are strongly linked to each other, exchanging information and collaborating."

The group connectome, with the nodes and connections colored according to their rich-club participation.
Green represents few connections. Red represents the most. The Journal of Neuroscience, 2011.

But what's going on in this special network? That's a good question. "You sort of wonder what they're talking about when they're communicating with each other," said Sporns. "All these regions are getting all kinds of highly processed information, from virtually all parts of the brain."

This part is still somewhat up for debate, but many areas of the rich club are involved in complex cognitive and behavioral processes. For this reason, the researchers suggest that damage to the rich club would lead to disproportionately large problems in brain function, while damage to the lesser networks would be relatively less severe. The team did find that the rich club network overlapped with several "functional modules" of the brain, like those involved in executive planning, vision, audition (hearing), and salience (relevance).

Study author Martijn van den Heuvel sums it up nicely by saying that the rich club network is like the "G8 summit of our brain. It's a group of highly influential regions that keep each other informed and likely collaborate on issues that concern whole brain functioning," he said. "Figuring out what is discussed at this summit might be an important step in understanding how our brain works."

Clearly more research will look into this elite network in the brain. Researchers have made a lot of recent progress in mapping out the brain's inordinate number of connections in what's referred to as the "connectome," and this study is one more piece in the massive puzzle.

"People are coming around to the idea that mapping the connectome is not only technically feasible but also very important to do," Sporns said. "It's a fundamental step toward understanding the brain as a networked system. Networks are everywhere these days, found in technology, social media and economics, ecology, and systems biology -- They're becoming more and more central in many areas of science. The human brain is perhaps the most challenging example to date."

The researchers published their study in the November 2, 2011, issue of the Journal of Neuroscience. It was carried out at Indiana University and at the Rudolf Magnus Institute of Neuroscience in the Netherlands.

Image: Oliver Sved/Shutterstock.

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