Neuroscience has long supported the idea that our brains need to be used to stay strong. Our brains aren't fixed; they are active, adaptable structures capable of amazing change, a process known as neuroplasticity. When we do challenging mental tasks – like learning a new language, solving a difficult problem, or even finding our way in an unfamiliar city – our brains build new connections and strengthen existing ones. If we don't give our brains enough mental stimulation, our thinking abilities can decline.