Grateful Dead drummer Mickey Hart is taking his love of rhythm and applying it to the medical field.

In the early '80s, Hart was caring for his grandmother, who had dementia. She no longer spoke, but when he played his drum for her, she smiled, a tear came to her eye, and she said his name. Hart says, "That was one of the key experiences in my life, which showed me what the power of rhythm can do. Rhythm was re-connecting her to the world that was fading away.”

Now Hart is collaborating with Adam Gazzaley, director of the Neuroscience Imaging Center at the University of California - San Francisco, in trying to understand the neuroscience of rhythm and to apply it to therapeutic uses. In other words, can the right external source of rhythm help a wounded brain enter a state of consciousness that it can no longer sustain on its own?