Brain 'pruning' linked to maturity

Teenage girls may mature faster than boys because of the way their brains are "pruned", scientists believe.

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Scientists believe teenage girls may mature faster than boys because of the way their brains are 'pruned'

Teenage girls may mature faster than boys because of the way their brains are "pruned", scientists believe.

New research shows that as we age, excess brain connections are cut back while those transmitting essential long-distance signals are preserved.

Studying a group of volunteers up to the age of 40, scientists found that this pruning of neurons takes place earlier in females than in males.

The study suggests that during the process brain function actually improves, since cutting back the connections prevents an overload of unimportant information.

Dr Marcus Kaiser, a member of the team from the University of Newcastle, said: "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.

"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 scientists used a special kind of magnetic resonance image (MRI) scan to peer into the brains of 121 healthy participants aged between four and 40.

Their findings are reported in the journal Cerebral Cortex.

As people get older, connections in their brains are thinned out as nerve fibres are pruned, the study showed.

But fewer connections between distant brain regions, brain hemispheres, and processing modules were lost than expected.

Loss of nerve fibres linking different regions of the brain was found to be highly selective - a phenomenon the scientists called "preferential detachment".

Co-author Sol Lim, from Seoul University in South Korea, said: "The loss of connectivity during brain development can actually help to improve brain function by reorganising the network more efficiently.

"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."