Seven brain structures are briefly described as they relate to the text. Brizendine claims that the anterior cingulate cortex (ACC), involved in decision-making and worrying, is larger in female humans; she also states that the prefrontal cortex, which manages emotional regulation, is larger and matures sooner in female brains than in male ones. Other structures include: the insula, the repository of gut feelings; the hypothalamus, which manages hormones; the amygdala, or the locus of instinct; the pituitary gland, which produces reproductive hormones; and the hippocampus, which impacts memory. The last is less active in male brains, according to Brizendine.

Relevant hormones are divided into two categories: those “your doctor knows about” and those “you doctor may not know about” (15)—an unscientific categorization that seemingly disparages Brizendine’s colleagues. Estrogen, progesterone, and testosterone fall into the first category, and oxytocin, cortisol, vasopressin, DHEA,