Mental illness is one of the greatest causes of human suffering, its nature and origin a long-held mystery. But thanks to new science and technology, our understanding has reached a tipping point. In Connections, Professor Karl Deisseroth intertwines his own breakthrough discoveries with moving case studies from his experience as an emergency psychiatry physician, in order to tell a wider story about the origins of human emotion. Addressing some of the most timeless questions about the human condition while illuminating the roots of misunderstood disorders such as depression, psychosis, schizophrenia and sociopathy, Connections transforms the way we understand the brain, and forges a bold new path forward in our understanding of mental health.