Complex tasks such as juggling¹ produce significant changes to the structure of the brain, according to scientists at Oxford² University.

牛津大学的科学家发现，诸如杂技类的复杂任务可以显著改变人脑的结构。

juggle³ with three balls" width="226" border="0" src="/upimg/091012/4_015900_1.jpg" />
The volunteers were taught to juggle with three balls

In the journal, Nature Neuroscience, the scientists say they saw a 5% increase in white matter - the cabling network of the brain.

The people who took part in the study were trained for six weeks and had brain scans before and after.

Long term it could aid treatments for diseases like multiple sclerosis（多发性硬化）.

Diffusion⁴ MRI

The team at Oxford's Department of Clinical Neurology used a diffusion MRI（磁振影像） which is able to measure the movement of water molecules⁵ in the tissues of the brain.

The signal changes according to how many bundles of nerve fibres there are and how tightly packed they are.

Changes in grey matter, where the processing and computation in the brain happens, have been shown before, but enhancements in the white matter have not previously⁶ been demonstrated.

Three ball cascade⁷

The scientists studied a group of 24 healthy young adults, none of whom could juggle.

They divided them into two groups.

One of the groups was given weekly training sessions in juggling for six weeks and was asked to practice 30 minutes every day the other 12 continued as normal.

After training, the 12 jugglers could perform at least two continuous cycles of the classic three ball cascade（小瀑布）.

Both groups were scanned using diffusion MRI before and after the training.

At the six week point, a 5% increase in white matter was shown in a rear section of the brain called the intraparietal（壁内的，顶骨内的） sulcus（槽，沟） for the jugglers.

This area has been shown to contain nerves that react to us reaching and grasping for objects in our peripheral⁸ vision（周围视觉）.

There was a great variation in the ability of the volunteers to juggle but all of them showed changes in white matter.

The Oxford team said this must be down to the time spent training and practising rather than the level of skill attained⁹.

Dr Heidi Johansen-Berg, who led the team, said: "MRI is an indirect way to measure brain structure and so we cannot be sure exactly what is changing when these people learn.

"Future work should test whether these results reflect changes in the shape or number of nerve fibres, or growth of the insulating（绝缘的） myelin sheath（髓鞘） surrounding the fibres.

"Of course, this doesn't mean that everyone should go out and start juggling to improve their brains.

"We chose juggling purely¹⁰ as a complex new skill for people to learn."

Clinical Applications

Dr Johansen-Berg said there were clinical applications for this work but there were a long way off.

She said: "Knowing that pathways in the brain can be enhanced may be significant in the long run in coming up with new treatments for neurological diseases, such as multiple sclerosis, where these pathways become degraded."

Professor Cathy Price, of the Wellcome Trust Centre for Neuroimaging, said: "It's extremely exciting to see evidence that training changes human white matter connections.

"This compliments（贺词，问候） other work showing grey matter changes with training and motivates further work to understand the cellular¹¹ mechanisms¹² underlying¹³ these effects."