Hormones and the BrainCrafting a Personality Through Hormones —iVnen she was 13, Mary Lou spent a whole summer in the intensive care ward of a hos-pital with a grave illness that doctors could not diagnose. When she finally got out of thefospital, she assumed that her life would be short, so Mary Lou pursued it with gusto,.•. ;'king as an artist, playing in a band, working on a PhD in electrical engineering at an. _eague school. But by her early 20s, Mary Lou's medical condition was deteriorat-ing. She was sleeping 20 hours per day, coping with constant headache and repeatedomiting, and periodically wheelchair bound, but the worst part for Mary Lou was that,x the first time in her life, she felt stupid.Then doctors finally detected a slow-growing brain tumor that had disruptedfunction : I a oea-sized structure called the pituitary gland. The tumor was removed, butthe pitu-•3'V was damaged beyond repair. As we'll learn in this chapter, the lack of afunctioning. :ary means Mary Lou fails to make a host of hormones, some of which are crucial :'survival. Fortunately, pharmacies can provide many of these missing hormones, so in e20 years after surgery, a recovered Mary Lou has been able to found several technologystart-ups and has headed projects, first for Google then Facebook, where she has ~zefforts in virtual reality.Taking hormones saved Mary Lou's life. But in the process of tinkering to get the right: ;es and combinations of hormones, Mary Lou learned that hormones influence notinly her physical health and intelligence, but also her moods and personality. As sheaays, "It took me years to craft a better 'me' after my personality was essentially killed>y the effects of the tumor and surgery" (Jepsen, 2013). What are these hormones thatLou must tinker with, and how can they have such a large effect on her brain andcehavior?cells in your body use chemicals to communicate, including an extensive array fhormones. Alterations in hormone levels can produce striking changes in brainion. Cognitive abilities, emotions, our appetite for food or drink or sex, ouraggressiveness or submissiveness, our care for children—the scope of hormonal in-fluences on behavior is vast. Furthermore, hormones do more than influence adultichavior. Early in life, thyroid and sex hormones regulate brain development. Latern life, the changing outputs of endocrine glands and the body's changing sensitivity3 hormones are prominent aspects of adolescence and aging. In this chapter weconsider the major hormones, their anatomical sources, their slogical actions, andtheir effects on behavior. This discussion sets the stage for apics in later chapters,such as hormonal effects in reproductive behavior (Chapter ! >: feeding, drinking,and body maintenance (Chapter 13); and stress and emotion Liter 15).