In order to understand how the brain works, it is essential to know what is computed by different brain systems, and how those computations are performed. Brain Computations: What and How elucidates what is computed in different brain systems and describes current computational approaches and models of how each of these brain systems computes. This approach has enormous potential for helping us understand ourselves better in health. Potential applications of this understanding are to the treatment of the brain in disease, as well as to artificial intelligence, which will benefit from knowledge of how the brain performs many of its extraordinarily impressive functions. Pioneering in its approach, Brain Computations: What and How will be of interest to all scientists interested in brain function and how the brain works, whether they are from neuroscience, or from medical sciences including neurology and psychiatry, or from the area of computational science including machine learning and artificial intelligence, or from areas such as theoretical physics.