The human nervous system is a complex and fascinating structure whose capabilities are far-reaching. How surprising is it that we know so much more about stars billions of light years away than our own brains? Why is the brain so mysterious? Well, studying the brain is a significant challenge. First of all, we cannot simply open the skull and observe the living brain, for obvious reasons. Second, the brain's many functions are at the molecular level, making them impossible to observe, even with the world's most powerful microscopes. According to the World Health Organization, "N eurological disorders, ranging from epilepsy to Alzheimer disease, from stroke to headache, affect up to one billion people worldwide. An estimated 6.8 million people die every year as a result of neurological disorders." Therefore, understanding the human brain is crucial.