Emotions like fear, anger, sadness, and joy enable people to adjust to their environment and react flexibly to stress and strain and are vital for cognitive processes, physiological reactions, and social behavior. The processing of emotions is closely linked to structures  in the brain, i.e. to what is known as the limbic system. Within this system the amygdala  plays a central role – above all it processes negative emotions like anxiety and fear. If the activity of the amygdala becomes unbalanced, depression and anxiety disorders may develop.