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Our complex brains thrive on the edge of chaos

Operating in a state that is neither ordered nor random may help drive our brain's astonishing capabilities

CHAOTIC thinking is rarely a recipe for success, but evidence is emerging that operating at the edge of chaos may drive our brain’s astonishing capabilities.

Neuroscientists have long suspected that the network of neurons in our brains might be connected in such a way that they achieve a state of “self-organised criticality” (SOC), in which they are neither ordered nor random, but somewhere in between. In such a state, even a minor change can prompt a large reaction: for example, forest fires, earthquakes and avalanches tend to propagate under SOC.

In 2003, neuroscientists showed that the propagation of electrical signals in a slice of brain tissue from a rat followed patterns expected for a state of SOC (). To see whether this was also true in people, of the University of Cambridge and his colleagues mapped electrical brain activity in 19 volunteers.

One mark of SOC is that signals should show similar patterns at all frequencies – a property known as scale invariance. Sure enough, when Bullmore’s team measured the length of time that two electrical signals from random locations in the brain were “in phase”, it was the same at all signal frequencies (PLoS Computational Biology, ).

Computer models have shown that when neural networks are in a state of SOC, they maximise information processing and storage. “It might be advantageous for the brain,” Bullmore says.

Topics: Brains / Psychology