Juggling for your brain

The BBC today reports that “complex tasks such as juggling produce significant changes to the structure of the brain”. These findings come from a study that performed brain scans on 48 volunteers before and after a six-week period, in which half of them were learning how to juggle. At the end of the study, jugglers showed a 5% increase in the white matter in an area at the back of the brain called the intraparietal sulcus. This is an area that is involved in “reaching and grasping for objects in our peripheral vision”.

This study indicates that learning a complex skill can result in changes in brain structure. This research will be of interest to the research community, but at the moment the practical implications of these findings are unclear. One of the authors suggests that this sort of knowledge could eventually help in developing new treatments for neurological diseases, but acknowledges that such clinical applications are a long way off.

Where did the story come from?

The research was carried out by Jan Scholz and colleagues from the Oxford Centre for Functional Magnetic Resonance Imaging of the Brain and the University of Oxford. The study was funded by the Wellcome Trust and the UK Medical Research Council. It was published in the peer-reviewed journal Nature Neuroscience .

What kind of scientific study was this?

This was a controlled study looking at the effect of learning to juggle on the brain. The researchers say that cross-sectional studies have shown that differences in brain structure have been linked to differences in behaviour, but the cross-sectional nature of these studies means that they could not prove that the behaviour was causing the differences seen.

The researchers enrolled 48 healthy adult volunteers (average age of 25) with no previous juggling experience. All of the participants received a brain scan using a technique known as DTI (diffusion tensor imaging) at the start of the study. Half of the participants were given juggling training, while the other half had no training.

The training group volunteers eached received three small beanbags and written instructions on how to learn a basic three-ball juggling pattern. They were asked to practise for half an hour a day, six days a week, for six weeks.

After six weeks, both groups of participants had a second DTI brain scan. The participants then had a third scan after a further four weeks during which they did not juggle. Two participants did not receive this third scan. The researchers then compared changes in various parts of the brain between the groups after six and ten weeks.

What were the results of the study?

After six weeks, all of the training group could perform at least two continuous cycles of three-ball juggling. The scans showed the control group had no brain changes. The training group had changes in an area at the back of the brain called the right posterior intraparietal sulcus after their six weeks of juggling training. These changes remained, even after four weeks of not juggling.

The researchers say the changes seen could in part have been caused by intricate changes in the thickness of the nerve fibres, or the amount of insulation around the nerve fibres. The training group also showed an increase in the density of their overlying grey matter in this area. This change was again not seen in the control group.

There was no clear relationship between the changes and how much a person’s juggling improved, or how well they could juggle by the end of the training. The researchers say this suggests the changes were more related to the time spent training rather than the skill gained.

What interpretations did the researchers draw from these results?

The researchers say that this is the first evidence for changes in the structure of the white matter of the healthy human adult brain as a result of training. They also say that the biological interpretation of the changes is complex, and further studies will be needed to understand exactly what changes are occurring at the level of the nerve cells.

What does the NHS Knowledge Service make of this study?

It was unclear how the participants were assigned into groups. If they were not randomly assigned there may have been imbalances between the groups that could have affected the results.
The study was carried out in healthy adults, so results may differ in children or people with medical conditions affecting the brain.
It is not clear whether changes in brain structure would remain after a longer follow-up period.