Your brain contains two kinds of tissue: gray matter (the billions of neurons that act as processors for your endless computations) and the lesser-known white matter (threadlike extensions of these nerve cells, which twist together to form the brain’s wiring). Neuroscientists believe that disruptions in the white-matter wiring may play a role in many neuropsychiatric disorders. The NIH-funded Human Connectome Project, launched in 2009, mapped the major white-matter “highways” in healthy adults. Anastasia Yendiki is among the first researchers to take this work to the next level, studying the brains of adolescents with depression and anxiety disorders to learn how their white matter differs from that of healthy subjects as well as other patients with similar diagnoses. “The difference between someone with depression or anxiety and someone [without] isn’t going to be so coarse as a missing highway,” she says. “We have to go deeper and map the smaller roads.” Early detection through white-matter scanning using next-generation MRIs, Yendiki explains, will ultimately enable more effective diagnosis and treatment.