MichellelMack and her mother (left) meet Alan

Conventional wisdom holds that we use only ten percent of our brains, but a remarkable young woman named Michelle Mack proves otherwise.

Michelle was born with half a brain. Her left hemisphere was almost completely destroyed by a stroke she suffered in her mother's womb. But Michelle's verbal and object-recognition capabilities, normally seated in the missing left brain, are hardly compromised.

An MRI scan reveals the missing left half of Michelle's brain

In "The Power of Half," meet Michelle and Dr. Jordan Grafman, of the National Institutes of Health outside of Washington D.C. Although their work together has just begun, it's already clear that Michelle's right hemisphere controls tasks handled by the left brain in other people. But this compensation comes with a price; Michelle struggles with visual-spatial tasks, which are normally processed in the right brain. It's as if the two abilities, linguistic and visual-spatial, had to duke it out for space in Michelle's brain- and language won.

Michelle's extraordinary case is yet more evidence that the brain is a flexible—and competitive—organ, always prioritizing and re-organizing. Stay tuned—Dr. Grafman's work with Michelle will be updated in a future episode of Frontiers.