Brain Plasticity - the story of Jody - --three. (SINGING) Cinderella dressed-- NARRATOR: We are beginning to harness the brain's incredible ability to invent itself then reinvent itself throughout life. This girl is a testament to the amazing resilience of the human brain. Young Jody Miller leads an idyllic life as a nine-year-old girl. You would never guess that she has undergone some of the most drastic surgery imaginable. [CHATTER AND LAUGHTER] - (SINGING) Happy birthday-- NARRATOR: Jody's first three years were textbook normal. - (SINGING) Happy birthday dear Jody, happy birthday-- NARRATOR: Then about six weeks after her third birthday, a storm of epileptic seizures took control of her brain. WOMAN VOICE OVER: --go back. Oh! - [CRIES] LYNN MILLER (VOICEOVER): She couldn't use her left arm hardly at all. She could barely use the left leg, seizing a good deal of the time, multiple types of seizures. NARRATOR: Ordinary life became impossible. Medicines did nothing, and the seizures threaten to turn fatal. Desperate, Jody's parents brought her to a pediatric neurologist Eileen Vining. EILEEN VINING: We found her seizures were all, all coming from her right hemisphere. And we knew that there is virtually nothing else, nothing but Rasmussen's syndrome that can produce that picture in a young child. NARRATOR: Rasmussen's syndrome is a degenerative brain disorder that disrupts the electrical activity that makes our brains work. Tiny electrical explosions were flaring up in Jody's right hemisphere. The seizures became almost constant. She lost control of her left side. Only one radical treatment option remained. EILEEN VINING: We knew that she was never going to have her seizures controlled with medicine, and we knew that she and her family faced taking out that half of the brain. NURSE: OK? NARRATOR: Dr. Vining recommended a daring surgery called a hemispherectomy. It would be performed by pediatric neurosurgeon Ben Carson. BEN CARSON (VOICEOVER): The whole concept of taking out half of a person's brain would seem to most people impossible. Human beings are incredible creatures with a brain that is beyond belief in terms of its capabilities, to the point where we can take half of it out and still function in a normal way. NARRATOR: 85% of our brain consists of the cerebral cortex, which is divided into two hemispheres, each with four main lobes. The cortex handles many of our higher functions. Areas on both sides control thinking, movement, and sensation. But the right side controls our left side and vice versa. Jodi would lose almost all of her right hemisphere, and the cavity would fill with cerebrospinal fluid. The operation has to be performed with great precision to avoid damaging the parts of the brain that control Jody's life functions, like heartbeat and breathing. [MUSIC PLAYING] [DRILL] The surgery went flawlessly. EILEEN VINING: What we're looking at here is an image, an MRI, that was done on Jody after her surgery, and what it shows us is the fact that we removed her entire right hemisphere. And what we're able to see here is indeed her very normal left hemisphere and all the beautiful gyri of her cortex. And we can see right down the middle, the right hemisphere that was there is now replaced by fluid. NARRATOR: But how could Jody function normally with only one hemisphere? It's because of a miraculous ability of the brain called plasticity. Our brains can actually change shape, creating new connections between neurons, or brain cells, to replace lost or damaged ones. Jody's left brain started reconnecting almost immediately. EILEEN VINING: At least as good as this, and if I remember, he wore pink, just like you! [LAUGHTER] This young lady had half her brain removed, went home, I guess maybe 10 days later, and was already walking! She was ambulating. She was able to walk out of the hospital! And that's because her left hemisphere had such resilience, such plasticity. It was able to say, OK, something needs to move her left leg. Whoa! You going to open it? OK. NARRATOR: Jodi continues to work on training her brain to overcome the slight paralysis in her left side. - --but enough-- now, that's very good. You need to do that stretching stuff, honey. You know that, don't you? Are you doing enough of it? No, I didn't think so. BEN CARSON (VOICEOVER): The human brain is just an awesome thing because every time I look at it, I say to myself, this is the thing that makes this person unique. It still is just such a wonderful thing to find a young person who's life now can move on, who's no longer having seizures, who's developing in a normal fashion. I take the good with the bad, and I say, this is a bad thing, potentially, that we have to do for an extremely good cause.