In a recent study of the brain's waste drainage system, researchers discovered a direct connection between the brain and its tough protective covering, the dura mater. These links may allow waste fluid to leave the brain while also exposing the brain to immune cells and other signals coming from the dura. This challenges the conventional wisdom which has suggested that the brain is cut off from its surroundings by a series of protective barriers, keeping it safe from dangerous chemicals and toxins lurking in the environment.