Opioid circuits and dopamine pathways are important components of what has been called the limbic system, or the emotional brain. The circuits of the limbic system process emotions like love, joy, pleasure, pain, anger, and fear. For all their complexities, emotions exist for a very basic purpose: to initiate and maintain activities necessary for survival. In a nutshell, they modulate two drives that are absolutely essential to animal life, including human life: attachment and aversion.
