The Limbic System
Diagram of Brain..
The brain parts that you do not often see in drawings is found deep within the brain. This brain part is called the limbic system and is involved in emotions and basic drives. Some refer to the limbic system as the lower brain, not only because of where it is located, but because it handles the things about us that are a bit less civilized. For example, the amygdala and nucleus accumbens are important for processing fear and reward. They are also involved in drug, alcohol and other addictions. The cingulate gyrus runs the day to day activities of the body that we do not directly control, like heart rate and blood pressure.
One interesting part of the limbic system that actually resides in the parietal cortex is called the hippocampus. The hippocampus is the brain part that forms memories. You have one of these on each side of the brain. If one hippocampus is injured, say by a stroke, the other one will still allow your brain to make memories. However, if both hippocampi are removed, as was once done through surgery, then you cannot form new memories! This horrible thing happened to a person that underwent surgery to prevent almost continuous, life-ruining seizures. After the surgery, it was found that the person could only remember things that happened prior to the surgery and could not make new memories. Each day, in fact each new moment was a confusing, perpetual question of â€œHow did I get here?â€ Needless to say this surgery never happens anymore but this terribly unfortunate occurrence demonstrates the importance of the hippocampus in memory.
Diagram of Brain...