Watch The Brain Our Universe Within online: Episode 3 The Miraculous Mind

For all its evolutionary armor, the human brain is still a fragile organ. Our skull provides the first line of defense against physical injury. On the inside, sheets of membrane covering the brain keep out invading germs and toxins. But even these safety barriers cannot stave off all injury. They are no match against a head-on collision or the missile force of a bullet. In fact, traumatic brain injury is the number one killer of people under thirty-four. There is a saying used by doctors, "Touch the brain, never the same." When injury, stroke or disease touch the brain, lives change profoundly. But some of these lives tell stories of quiet victories, of miracles, both great and small. And these tales also open a window to the remarkable capacities of the brain, its power to repair and restore itself - a power we are just beginning to discover and understand.

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