Understanding how the brain works is one of the most complex and exciting challenges in science. If we succeed, we can better grasp what it means to be human, help “fix” the brain when diseases cause it to malfunction, and inspire better artificial intelligence. To gain this understanding, we need tools that let us break the brain down into its building blocks, see how they work, and control their activity. In this article, I describe optogenetics—a method for controlling brain activity with light—and how combining optogenetics with other tools may bring us closer to truly understanding the brain—and what it means to be human.
