How complex is the brain? With over 10 billion neurons, each connecting with thousands of other neurons, even one small change to the brain can alter someone's beliefs, abilities, memories, and countless other characteristics. But how do scientists know that the brain is the control center of our personalities and motor skills? Find out the answer to these questions and more through a short video from Dr. David Eagleman. Continue your exploration of the brain with the other videos in the series, which can be found in the Additional Materials section.