No matter what you're afraid of — snakes, spiders, slasher flicks or public speaking — the brain follows its instincts. In this video, Abigail Marsh, associate professor of psychology at Georgetown College, explains how multiple pathways in the brain can trigger a response to fear. When you see something scary, a bundle of brain cells triggers the amygdala, which then releases cortisol thereby increasing stress.

Within a few seconds, your whole body gets involved. Nerve cells start to release endorphins and dopamine, the neurotransmitter best known for ushering in a "feel good" sensation. Soon, the initial feeling of fear passes and your body begins to calm down and your brain's frontal cortex is able to release signals that tell you to calm down.

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