How does the brain work? How do billions of neurons bring about ideas, sensations, emotions, and actions? Why do children learn faster than elderly people? What can go wrong in perception, thinking, learning and acting? Scientists use computer models to help us to understand the most private and human experiences. In this work, Manfred Spitzer shows how these models can fundamentally change how we think about learning, creativity, thinking and acting, as well as such matters as schools, retirement homes, politics, and mental disorder. Neurophysiology has told us a lot about how neurons work; neural network theory is about how neurons work together to process information. Spitzer provides a basic, nonmathematical introduction to neural networks and their clinical applications. Part 1 explains the fundamental theory of neural networks and how neural network models work. Part 2 covers the principles of network functioning and how computer simulations of neural networks have profound consequences for our understanding of how the brain works. Part 3 covers applications of network models (for example, to knowledge representation, language, and mental disorders such as schizophrenia and Alzheimer's disease) that shed light on normal and abnormal states of mind. Finally, Spitzer concludes with his thoughts on the ramifications of neural network for the understanding of neuropsychology and human nature.