For 170 years, medicine has placed human beings into the suspended state of anesthesia without fully reckoning with what that suspension does to the brain's inner architecture. A study published in Science Advances now reveals that ketamine — a drug used both to silence pain and to treat despair — quietly remodels the female brain in ways it does not touch the male, driven by a cascade of stress hormones and immune cells acting in concert. The finding is a reminder that the body is not a universal instrument, and that the drugs we offer it may play entirely different songs depending on who rec