A “startle response” or “startle reflex” is when people jump at the sound of a loud, unexpected noise. The reflex is generally dependent on cues: it can be made stronger by viewing negative photographs, such as traffic accident victims; it can be made weaker by positive photographs, such as happy babies and favorite foods. The amygdala is essential for the changes in the defensive startle reflex. The amygdala is involved in forming emotions in response to exposure to aversive emotional pictures or warning cues that an individual sees and hears (Levenston et al 2000). The amygdala is controlled in part by the brain’s dopamine system, the same system that responds to alcohol and produces feelings of pleasure when good things happen.
