Physicians noted, for example, that damage to one side of the brain often caused numbness or paralysis on the body"s opposite side, suggesting that the body"s right side is wired to the brain"s left side, and vice versa. Others noticed that damage to the back of the brain disrupted vision, and that damage to the left-front part of the brain produced speech difficulties. Gradually, these early explorers were mapping the brain. In primitive animals, such as sharks, a not-so-complex brain primarily regulates basic survival functions: breathing, resting, and feeding. In lower mammals, such as rodents, a more complex brain enables emotion and greater memory. In advanced mammals, such as humans, a brain that processes more information enables foresight as well: the cerebellum enables one type of nonverbal learning and memory. It helps us judge time, modulate our emotions, and discriminate sounds and textures (bower & parsons, 2003).