Stress creates rapid molecular changes inside the amygdala, the brain region that processes fear, alertness and emotional reactions. When the body senses a stressful event, nerve pathways send fast signals to the amygdala. This activates cells that release chemical messengers such as glutamate. Glutamate makes nearby neurons fire more easily, raising the overall activity level of the region. At the same time, stress hormones released from the adrenal glands begin to reach the brain through the b