Giffords suffered from aphasia -- the inability to speak because of damage to the language pathways in her brain's left hemisphere. But by layering words on top of melody and rhythm, she trained her brain to use a less-traveled pathway to the same destination.
"Music is that other road to get back to language," said Meaghan Morrow, Giffords' music therapist and a certified brain injury specialist at TIRR Memorial Hermann Rehabilitation Hospital in Houston. Morrow compared the process to a freeway detour.
"You aren't able to go forward on that pathway anymore," she said, but "you can exit and go around, and get to where you need to go."
The brain's ability to pave new pathways around damaged areas is called neuroplasticity. An adult can relearn to speak -- with the right training and a lot of practice, according to Dr. Gottfried Schlaug, associate professor of neurology and director of the Music and Neuroimaging Laboratory at Beth Israel Deaconess Medical Center and Harvard Medical School.
Schlaug compared the process to learning to play the piano at age 50 or 60.
"It would be a much more laborious process to do that than if you were to start at the age of 6 or 7," he said.
The brain is a network of connections. The ones most used become reinforced over time -- like freeways. The weaker connections are still there, but as smaller back roads.
To help recover speech, the connection has to be turned from a one-lane road into a super highway, said Schlaug.
Through functional magnetic resonance imaging, scientists have begun to map the brain's many functions to specific regions. Whereas language is largely held in the left side of the brain, music activates visual, motor and coordination areas on both sides as well as areas deep in the brain involved in memory and emotion.
"It has been known literally for centuries that speechless people, people who have lost speech, may sing," he said, citing an 1871 article by neurologist Dr. John Hughlings Jackson titled, "Singing by Speechless Children."
"It was known, but it was not explored or exploited," said Sacks.
In the past decade, music's ability to access language in the brain has been explored in great detail, and exploited as a means of recovering speech after brain injury.
These patients "have some words somewhere," but must be "tricked or seduced into discovering them," said Sacks.
But many people remain skeptical about the benefits of music therapy, and few insurers cover it. Schlaug is currently conducting a clinical trial of "melodic intonation therapy" in aphasic stroke patients, comparing it with speech therapy or no therapy at all.
Schlaug's trial involves 75 intensive one-hour therapy sessions. The therapy can be frustrating and emotional for aphasic patients, whose inability to speak is no reflection on their intelligence.
That frustration was visible in Giffords' face, said Morrow. But the results were well worth the effort.
"It took a few days, but she started to give me a thumbs-up," said Morrow. "Then she would start opening her mouth giving a little hum. Then it would turn into words over the weeks."
And through ditties like "Happy Birthday," "American Pie" and her favorite, "Brown Eyed Girl," Giffords slowly paved the back road to language.
"When I first saw Gabby and I first sang the song with her," said Morrow, "I knew that things were going to get better."