The scientific literature on nostalgia usually refers to nostalgia regarding the personal life and has mainly studied the effects of nostalgia induced during the studies. Smell and touch are strong evokers of nostalgia due to the processing of these stimuli first passing through the amygdala, the emotional seat of the brain. These recollections of one's past are usually important events, people one cares about, and places where one has spent time. Music and weather can also be strong triggers of nostalgia.