What Does It Mean That Your Brain Is Missing a Cerebrum?

Article: The cerebellum is a part of the brain that holds half of our neurons. But until now, scientists haven't known exactly all that it allows us to do or not do. Thanks to some people born without cerebellums or cerebellums damaged due to stroke, infection or disease--and willing to have their brains scanned and studied--we are learning a lot more. Until now, scientists thought the cerebellum was only responsible for helping us keep our balance and fine motor control. So when one gets drunk and fails a police walking test or can't touch the tip of their nose, that is the cerebellum impaired. (Kids: try walking in a straight line; that is your cerebellum helping you out.) But now we also know that the cerebellum is like the fine tuner to most of our other functions. Other parts of the brain enable us to do things-- like telling us when to walk or speak or feel an emotion--but the cerebellum fine tunes that and helps us do it well -- walk well, speak in an understandable way, or show empathy. For instance, one person in the study who was born without a cerebellum could walk, talk, think and express some feelings, but none very well. In a conversation, he speaks slurred and can only say basic things, like "how are you? how was your day?" But if the conversation progresses beyond that, like someone saying "I felt sad today. My friends were mean to me," his brain cannot process the next step of where to take that conversation. Or if he were driving, he could drive in a straight line, but could not process what to do if a car honked at him and a bus pulled in front of him and he had to figure out what to do next.