Why Girls Mature Faster Than Boys: Brain Connections are Key

It's long been known that girls mature faster than boys during their teenage years. Now, researchers may have found out why. The brain re-organizes connections throughout our lives, and this process begins earlier in girls, which could explain the higher level of maturity.

In order to better understand what happens when the brain reorganizes itself, the researchers evaluated the scans of 121 healthy participants between the ages of 4 and 40 years. More specifically, they used a non-invasive technique called diffusion tensor imaging to demonstrate that fibers in the brain and pruned during this rather large span of life.

"Long-distance connections are difficult to establish and maintain but are crucial for fast and efficient processing," said Marcus Kaiser, one of the researchers, in a news release. "If you think about a social network, nearby friends might give you very similar information--you might hear the same news from different people. 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."

In this case, the researchers found that while long-range connections are affected with time, not all of them are affected to the same extent. Changes were influenced differently depending on the types of connections. Projections that are preserved were short-cuts that quickly link different processing modules and allow fast information transfer and synchronous processing.

In fact, the researchers demonstrated for the first time that the loss of white matter fibers between brain regions is a highly selective process. In addition, the connections between distant brain regions, brain hemispheres and processing modules lose fewer nerve fibers during brain maturation than expected. This is how we retain a stable brain network during maturation.

"The loss of connectivity during brain development can actually help to improve brain function by reorganizing the network more efficiently," said Sol Lim, one of the researchers, in a news release. "Say instead of talking to many people at random, asking a couple of people who have lived in the area for a long time is the most efficient way to know your way. In a similar way, reducing some projections in the brain helps to focus on essential information."

The findings are published in the journal Cerebral Cortex.