In 1955, Bernard Brodie and Arvid Carlsson found that an herbal drug called reserpine seemed to make animals " lethargic, " " apathetic, " and " depressed."

1955 年，Bernard Brodie 和 Arvid Carlsson 发现，在摄入了一种名叫蛇根碱的草药后，动物会表现出“无精打采”、“无动于衷”以及“情绪低落”等多种症状。