As early as the post-World War II era, physical therapists noticed that Big Band music helped wounded veterans get up and learn to walk again, said Lee Anna Rasar, a musical therapist at the University of Wisconsin, Eau Claire.
Since then, researchers have documented a consistent pattern. When given a rhythm to walk to, people with Parkinson's disease, strokes and other forms of neurological damage are able to regain a symmetrical stride and a sense of balance. Each beat serves as an auditory cue that the brain uses to anticipate timing and regulate footfalls.
In the last decade, researchers have also begun to demonstrate ways that music-based therapies can help with speech recovery. In particular, a type of treatment called melodic intonation therapy has shown the greatest promise, Rasar said. Using a combination of rhythm, pitch, vision and hearing, the brain manages to sing words that it can't say.
For Giffords, therapy started with songs like "Happy Birthday," said Maegan Morrow, the Congresswoman's music therapist at TIRR Memorial Hermann Rehabilitation Hospital in Houston. At first, Giffords would simply sing the word "you" after Morrow sang, "Happy Birthday to..."