Study leader Dr. Marcus Kaiser and Sol Lim at Newcastle University in England say as people grow and mature, the brain undergoes a major reorganization reducing the connections in the brain and as the overall connections in the brain get streamlined, long-distance connections that are crucial for integrating information are preserved.
"Long-distance connections are difficult to establish and maintain but are crucial for fast and efficient processing. If you think about a social network, nearby friends might give you very similar information -- you might hear the same news from different people," Kaiser says in a statement.
"People from different cities or countries are more likely to give you novel information. In the same way, some information flow within a brain module might be redundant whereas information from other modules, say integrating the optical information about a face with the acoustic information of a voice is vital in making sense of the outside world."
The researchers say they suspect this newly-discovered selective process might explain why brain function does not deteriorate -- and indeed improves -- during this pruning of the network.
Kasier and Lim, along with colleagues in Glasgow University in Scotland and Seoul University in South Korea evaluated the brain scans of 121 healthy participants ages 4-40.
The researchers demonstrated the loss of white matter fibers between brain regions is a highly selective process -- a phenomenon they call preferential detachment. They show connections between distant brain regions, between brain hemispheres, and between processing modules lose fewer nerve fibers during brain maturation than expected.
The findings were published in Cerebral Cortex.