Your Emotional Brain
Your brain gets information from two different sources: Your senses tell you what's going on in the outside world, while your emotions exist inside your body to tell you what these events and circumstances mean to you. Just as hunger motivates you to find food, emotions motivate you to take care of other needs--like safety and companionship--that ultimately promote survival and reproduction.
How it Works
Emotions are controlled by the levels of different chemicals in your brain, but there is no one "love" or "hate" chemical. At any given moment, dozens of chemical messengers, or neurotransmitters, are active. Some of these neurotransmitters go between individual cells, while others are broadcast to entire brain regions. By layering signals on other signals, your brain can adjust how you respond to things and can effectively alter your mood. If you're in danger, for example, your brain releases stress hormones that make you react faster, flooding certain regions with the neurotransmitter epinephrine (adrenaline). When the danger subsides, your brain sends out a calming signal in the form of chemicals that dampen the response of regions that create fear.
When you're feeling an emotion, it's often written all over your face. While all mammals produce basic emotions like fear and anger, humans have especially highly developed social emotions, such as shame, guilt, and pride, which involve an awareness of what other people think and feel about us.
Beyond Our "Lizard Brain"
Lizards and humans share similar brain parts, which they inherited from fish. These parts handle basic body functions like breathing, balance, and coordination, and simple survival urges like feeding, mating, and defense. Together, these parts--the brain stem, cerebellum, and basal ganglia--are casually referred to as your "lizard brain." How are mammals different from lizards?
Millions of Americans take antidepressant drugs that alter how the brain processes serotonin, a neurotransmitter linked to feelings of serenity and optimism. These drugs, called selective serotonin reuptake inhibitors (SSRIs), increase levels of serotonin in the synapse by blocking its removal. What happens to the brain when an antidepressant is introduced? What other practices can be implemented to combat depression?
What is love? Neuroscientists can't answer that question yet. But they have learned more about how the feelings that occur when people "bond" are produced in the brain. If you look at how humans bond with their mates and care for their young, you'll see some surprising similarities between us and other species. Can family bonds be strengthened and weakened by chemicals in your brain?