“Use it or lose it” applies as much to the mind as to the body. Evidence suggests that a fair fraction of the observed loss of physical strength and fitness with age is lack of activity and training rather than inexorable processes of aging – though those inexorable processes exist, and will kill you if nothing is done about them. The situation is most likely similar for the brain. Not all of the observed loss is necessary or inevitable, even given the present lack of effective rejuvenation therapies that can address the causes of age-related neurodegeneration. Some fraction of the decline occurs because people choose to not to stretch their minds as much as they might. How large is this fraction? That is an interesting question without any precise answer at this time.
For a long time, it has been assumed that brain plasticity peaks at young age and then gradually decreases as one gets older. Interestingly, thanks to tremendous advances in medical imaging techniques for assessment of brain structure and function, mounting evidence for lifelong brain plasticity has been generated over the past years. In the context of practice-induced task learning, a key question