Juggling and probably other visual skills that take time to master increase the size of your brain, say researchers, challenging the traditionally held view that the anatomical structure of the normal adult human brain does not alter.

MRI scans found that learning to juggle increased by about three per cent the volume of grey matter in the mid-temporal area and left posterior intra-parietal sulcus, which process data from visual motion. The increase subsided if the subject did not maintain practice.

The change could be caused by an increase in production of neurons or connections between the cells, the authors speculated.

The study is published Jan. 22 in Nature.