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In 2003, 39-year-old Terry Wallis uttered his first word ("mom") in the 19 years since a car accident had left him with severe brain damage. He had spent much of the previous two decades in what neurologists call a minimally conscious state, somewhere in the gray area between coma and consciousness. In the years before his awakening, however, Wallis's family had noticed that he was growing more alert and responsive, occasionally nodding, grunting, or even crying, until one day he spontaneously started to speak. Though Wallis still has serious impairments in memory and movement, he continues to make remarkable gains.

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