Juggling matters on the brain

UK scientists have used magnetic resonance imaging to reveal that learning a complex task like juggling can causes changes in the white matter in the brain. The findings could have implications for developing new approaches to neurodegenerative diseases, such as multiple sclerosis.

In 2008, US researchers reported that surfing the net could apparently boost brain power, essentially the same results were reported again in October by the mainstream media. However, UK scientists have discover that a much older human skill can boost white matter in the brain - juggling.

Writing in the journal Nature Neuroscience, Heidi Johansen-Berg of the Department of Clinical Neurology, at the University of Oxford, explains that juggling appears to improve connections in parts of the brain involved in making the movements necessary to catch the balls as one throws them skyward from hand to hand.

"'We tend to think of the brain as being static, or even beginning to degenerate, once we reach adulthood,' explains Johansen-Berg, however, there is growing evidence of plasticity, which may one day be good news for those working to develop novel therapies for brain injury victims and stroke patients.

"We find the structure of the brain is ripe for change," adds Johansen-Berg, "We've shown that it is possible for the brain to condition its own wiring system to operate more efficiently."

Johansen-Berg and her colleagues Jan Scholz, Miriam Klein, and Timothy Behrens in the Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB) hoped to demonstrate plasticity in the white matter of the adult brain. To do this, they needed a task stimulating enough to putatively trigger new connections and changes in the brain. Juggling is just such a task requiring a novice to use their inherent hand-to-eye coordination in a new way to develop the skill.

Johansen-Berg points out that the white matter in the brain consists of bundles of long nerve fibres that conduct electrical signals between nerve cells and connect different parts of the brain together. The more familiar "grey matter" consists of the nerve cell bodies where the brain does its processing and computation. Other researchers have already demonstrated plasticity in the grey matter where new experiences and learning new skills cause changes. However, this is the first demonstration of enhancements in the white matter.

The Oxford team has developed a new approach to measuring changes in white matter based on assessing diffusion MRI images. Their approach lets them compare the anatomical features of white matter between individuals or over time.

"We detected a localized increase in fractional anisotropy, a measure of microstructure, in white matter underlying the intraparietal sulcus following training of a complex visuo-motor skill," the team says, "This provides, to the best of our knowledge, the first evidence for training-related changes in white-matter structure in the healthy human adult brain."

The team studied a group of healthy young adults, none of whom had ever learned to juggle. They divided them into two groups of 24 people. One group were given weekly juggling lessons for six weeks and asked to practice for at least half an hour each day. The team scanned the members of each group using diffusion MRI before and after the six-week period.

They saw changes in the white matter of the juggling group compared to the others who had received no training. The changes were in regions of the brain which are involved in reaching and grasping in the periphery of vision, so that seems to make a lot of sense, team member Jan Scholz explains.

"This exciting new result raises a lot of questions," says Johansen-Berg, "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 myelin sheath surrounding the fibres."

There were big differences between juggling ability in the trained group. All participants could juggle three balls for at least two cascades, but some of them learned how to juggle five balls and perform various tricks. Although there were big differences in white matter between the jugglers and the non-jugglers there was little difference in changes between the different jugglers regardless of the skill level attained. This suggests that the changes in white matter are determined by the time spent training and practising rather than the results achieved.

"Of course, this doesn't mean that everyone should go out and start juggling to improve their brains," concedes Johansen-Berg. "We chose juggling purely as a complex new skill for people to learn. But there is a 'use it or lose it' school of thought, in which any way of keeping the brain working is a good thing, such as going for a walk or doing a crossword." Or, indeed, the learning to surf the net reported in 2008 by US researchers.

"There are potential clinical applications of this work, although they are a long way off," adds Johansen-Berg. "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."

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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