In order to do this, Kalogeraki and her co-authors used a standard test to assess the brain's 'plasticity' -- its ability to change the way it activates in response to an experience. When the visual input of one eye is compromised for a couple of days, then the part of the brain that processes visual information gets preferentially activated by the other, open eye. The brain's ability to change eye dominance (called ocular dominance plasticity) is age-related, being most pronounced in juvenile animals and completely absent in older mice that have been raised without any stimulation. As well as confirming existing knowledge about the anti-aging effects of voluntary physical exercise -- older mice that exercised retained the ability to change eye dominance in comparison to those that didn't -- the study also revealed some exciting new findings. Those mice that had free-access to a running wheel were able to maintain ocular dominance plasticity after suffering a stroke, compared to those that didn't. "We found that mice with free access to a running wheel throughout their life preserved a more juvenile brain into adulthood and were able to prevent the negative effects of a stroke," reveals Kalogeraki. That was not all -- in addition, the researchers observed that exercise could even be used therapeutically after suffering a stroke. "We also found that mice with no previous access to a running wheel showed an equally positive recovery if voluntary exercise started after a stroke had occurred," adds Dr. Justyna Pielecka-Fortuna, co-author of the study. - www.sciencedaily.com