In contrast to the highly evolved prefrontal cortex, the limbic system is an ancient collection of structures located much deeper in the brain (even early mammals one hundred million years ago had limbic systems). The limbic system is the emotional part of the brain and is responsible for things like excitement, fear, anxiety, memory, and desire. It is primarily composed of four regions: the hypothalamus, the amygdala, the hippocampus, and the cingulate cortex. The hypothalamus controls stress. The amygdala is the key to reducing anxiety, fear, and other negative emotions.
