Our brain cells are changing all the time. They’re full of chemicals that send messages from one cell to another, but they’re much faster than the telephone! If scientists had a way of looking at those chemicals in our brains as they change, it would help them find out more about how our brains work, and help figure out how to treat diseases in our brains when they’re not working properly. Now nanotechnology gives scientists a way to do that, by using very tiny molecules that change color when they meet up with the chemicals in our brian cells. We say that these tiny molecules are fluorescent, because they give off a special kind of light. Do you know what a black light is? Have you ever seen your white t-shirt glowing under a black light? That glow is also a kind of fluorescence. Imagine that scientists can hold up a black light to our brain cells and see how much of a certain chemical is present by how much it glows. By watching how the glow changes over time, they can get a better idea of what a healthy brain looks like as compared to a diseased brain. This will help them make better drugs for treating diseases like Alzheimer’s and Parkinson’s Disease, and help us keep our brains healthy longer!