A child's brain is a magnificent engine for learning. A child learns to crawl, then walk, run and explore. A child learns to reason, to pay attention, to remember, but nowhere is learning more dramatic than in the way a child learns language. As children, we acquire language -- the hallmark of being human. In nearly all adults, the language center of the brain resides in the left hemisphere, but in children the brain is less specialized. Scientists have demonstrated that until babies become about a year old, they respond to language with their entire brains, but then, gradually, language shifts to the left hemisphere, driven by the acquisition of language itself. As children, we acquire language-- the hallmark of being human. But if the left hemisphere becomes the language center for most adults, what happens if in childhood it is compromised by disease? Brain seizures such as those resulted by epilepsy and Rasmussen's syndrome, have a devastating effect on brain development in some children.