You are What You Think?

In chapter two of The Shallows by Nicholas Carr, the subject of our vital paths affecting how we act is brought up through an experiment. Earlier, neurologists had proven that repeated actions can rewire our brains and neural circuitry. The experiments they had done led other neurologists to believe that our vital paths could be rewired purely through mental activity. To take this theory even further, Pascual-Leone discovered even more evidence to prove earlier conclusions. In his experiment, Pascual-Leone had one group of people practice a melody on a keyboard two hours a day, for five days. While this group was physically practicing the melody, he had another group of people simply imagine playing the melody in their minds. He later discovered that the brains of the group who had only imagined playing the melody had gone through the same exact changes of the group who had physically played the melody every single day. He later states that "our thoughts can exert a physical influence on, or at least cause a physical reaction in, our brains". He also explains that we "neurologically" become what we think.
Most neurologists believe that our brains can be rewired, but do you agree? Was this experiment liable or was it silly? Do you believe that through our thoughts we can physically become what we had only imagined?