Healthy humans use all of their brain. There is no part of the brain that goes unused. Certain tasks work certain parts of the brain more, but they all play important roles, as explained by neurobiologist Dr. Eric Chudler. Brain maps, as found in modern anatomy books, indicate that each part of the brain has a specific function essential to a healthy human. If there were a part of your brain that really went unused, then you could safely damage that part in an accident with no ill effects. But decades of medical records show that damage to any part of the brain has severe effects. If 90% of the brain were not used, then 90% of the brain tumors would cause no problem. Imagine brain doctors telling 90% of their cancer patients, "I have good news and bad news. Bad news: you have a brain tumor. Good news: it's in the part of the brain that you will never use." The thought is absurd.