That dark spot is the hole where a cerebellum should be. (Feng Yu et al)

A woman in China's Shandong Province checked into the hospital for dizziness and nausea, but her diagnosis took doctors by surprise: She was missing a big chunk of brain. Specifically, she lacked a cerebellum -- a tiny mass in the back of the skull that holds more neurons than the rest of the organ combined. The results of her examination were published last month in the journal Brain.

The patient reported that she'd always had trouble maintaining her balance (not surprising, since the cerebellum is important in motor control) and that she hadn't been able to walk at all until she was 7. Her speech was slurred as a child (again, not surprising -- scientists are pretty sure that the cerebellum plays a part in language development), but was intelligible by the time she was 6.

So essentially, it took less than a decade of life for the rest of her brain to pick up the missing cerebellum's slack. The fact that the patient is alive and thriving is incredible. This is only the ninth time that doctors have found someone to be missing a whole cerebellum, and most of the others have only been discovered after their early deaths. Studying the case will help scientists understand neuroplasticity -- the ability of the brain to adapt itself to changes in behavior, environment, or the body.

You can read more about the case at New Scientist, and find more information about neuroplasticity at io9.