So, If practice with activities like driving, braille reading and guitar playing result in structural and functional changes in the brain, what about mental practice?

In 1995, Pascual-Leone and his colleagues at Harvard Medical School asked a group of research participants to practice a five-finger piano exercise for 2 hours a day for 5 days. After the day’s practice, members of the group were tested with a transcranial-magnetic-stimulation (TMS) test that permitted the researchers to estimate the activity of neurons in the motor cortex, or that part of the brain that reflected the piano practice. With each day’s practice, the area of cortex devoted to the practice grew larger. The researchers then introduced a new twist. They instructed another group just to ‘imagine’ themselves playing the piano, holding their hands still while imagining themselves playing the scales. This group was tested as well and, quite remarkably, the same parts of the brain’s cortex expanded in similar ways both for the real players and the virtual players.