Can we exercise our brain to improve at difficult mental tasks?

Check out the research MRI scans on retired professional musicians brains age 70+ tested at Illinois University USA and another university in France near Paris
They have discovered that playing musical instruments with both hands and some also used both feet for organs harps percussion etc stimulates the brain cells and this shows up as super sparkly cells that have not deteriorated as fast as others of similar retirement age -hence the expression if we don't use it and move it we lose it
Thus playing music eg simple hand held chime bars with elderly retired groups and children and disabled adults using Chinese style simple numbers as poster music could stimulate memories and help reduce dementia problems Playing instruments does help a child's cognitive skills especially for learning reading skills and new languages -a series of trials were done daily as 'brain gym' simple exercises in Norfolk primary schools for ten minutes before school lessons and at lunchtime and at the end of lessons in 2008-2010 and class attention and learning skills did improve .Worth testing again with more counties and primary schools as they are very easy and are used by the Armed services and Police force to improve and sharpen reaction times in combat skills and in some sports UK teams at Loughborough and other FE Colleges sports departments- exercising the brain as well as the physical muscles of the body is definitely really important and not always understood