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12 Connected Neural Hubs Control 100% of The Brain: #OccupyConsciousness

Not all brain regions are created equal – instead, a “rich club” of 12 well-connected hubs orchestrates everything that goes on between your ears. This elite cabal could be what gives us consciousness, and might be involved in disorders such as schizophrenia and Alzheimer’s disease.

As part of an ongoing effort to map the human “connectome” – the full network of connections in the brain – Martijn van den Heuvel of the University Medical Center in Utrecht, the Netherlands, and Olaf Sporns of Indiana University Bloomington scanned the brains of 21 people as they rested for 30 minutes.

The researchers used a technique called diffusion tensor imaging to track the movements of water through 82 separate areas of the brain and their interconnecting neurons. They found 12 areas of the brain had significantly more connections than all the others, both to other regions and among themselves. “These 12 regions have twice the connections of other brain regions, and they’re more strongly connected to each other than to other regions,” says Van den Heuvel. “If we wanted to look for consciousness in the brain, I would bet on it turning out to be this rich club,” he adds.

Members of The Elite

The elite group consists of six pairs of identical regions, with one of each pair in each hemisphere of the brain. Each member is known to accept only preprocessed, high-order information, rather than raw incoming sensory data. Best connected of all is the precuneus, an area at the back of the brain. Van den Heuvel says its function is not well understood, but thinks that it acts as an “integrator region” collating high-level information from all over the brain.

Another prominent hub is the superior frontal cortex, which plans actions in response to events and governs where you should focus your attention. The superior parietal cortex – the third hub – is linked to the visual cortex and registers where different objects in your immediate vicinity are. To bring memory into the equation, the hippocampus is another hub – that’s where memories are processed, stored and consolidated. The fifth member of the club is the thalamus, which, among other things, interlinks visual processes; the last member, the putamen, coordinates movement.

Together the hubs enable the brain to constantly assess, prioritise and filter incoming information, and then puts it all together to make decisions about what to do next. This network makes the way the brain functions more robust overall, but it could also leave the entire system vulnerable to breakdown if key hubs are damaged or disabled, says Van den Heuvel.

Downfall of The Rich

After mapping the connections, Van den Heuvel’s team manipulated the data to see what might happen if parts of the rich club were damaged. The simulated brain lost three times as much function if the elite hubs were taken out than if random parts of the brain were lost.

“If [one of these] regions goes down, it can take the others down too, just like when banks failed in the global economic crisis,” says Van den Heuvel. Such vulnerability probably has great relevance to diseases such as schizophrenia, which is known to result from faulty connectivity within the brain, he says. It could also have role in Alzheimer’s disease, Parkinson’s disease and autism.

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