The human brain is a vast network of billions of neurons. For more than a century, that dizzyingly complex neuronal code was thought to be the sole arbiter of perception, thought, emotion, and behavior, as well as related health conditions. If you wanted to understand the brain, you turned to the study of neurons: neuroscience. But a recent body of work from several labs provides the strongest evidence yet that a narrow focus on neurons is woefully insufficient for understanding how the brain wo