How does the brain learn movement? Bridging the gap between behavioral processes and functional imaging signals

From the fluid grace a of ballet dancer to the lightning finger-speed of a concert pianist, the ability to produce skillful movements is one of man's most astonishing capabilities. Motor control, however, is a hard problem -- complex computations are necessary to control even the most mundane of movements. One can appreciate this fact when noting that even advanced robotic devices only poorly approximate human performance, or when watching a stroke victim try to relearn motor skills once taken for granted.

What happens in the human brain when we learn new motor skills? Because recovery from stroke and healthy motor learning are likely driven by overlapping mechanisms, this question is not only important to basic neuroscience, but also has profound clinical implications. Functional magnetic resonance imaging (fMRI) is one of the most powerful techniques for studying activity in the human brain and ought to play a key role in answering this question. However, despite many efforts over the past two decades fMRI studies have contributed disappointingly little to our understanding of motor learning. Hundreds of published studies have resulted in a bewildering and often inconsistent picture of activation changes, without providing a satisfying answer to what "more"