Brain circuits controlling fear, aggression, and mating operate through distinct neural pathways in the hypothalamus and involve estrogen receptors, not testosterone. Dr. David Anderson reveals how emotional states persist beyond triggering stimuli, generalize across contexts, and are shaped by hormones and neuropeptides like tachykinin—with implications for treating aggression, social isolation effects, and mental health. Emotions are persistent internal states that outlast their triggers and generalize across situations, unlike reflexes that terminate when stimuli stop. Estrogen receptors in the ventromedial hypothalamus, not testosterone, drive male aggression; testosterone's effects are mediated through conversion to estrogen via aromatase.