Essentials of Functional MRI is explained from the basic theory underlying magnetic resonance imaging. This includes how it can be used to detect dynamic variations in neural activity to become “functional” MRI, and how fMRI can be used for a variety of applications. The reader will gain an understanding of how fMRI is currently used, its limitations, and how it is still developing. This is achieved by explaining the core concepts and building on them to explain how fMRI data are acquired and what physiological information they provide. These ideas are the key to understanding how the data are analyzed to detect physiological changes that are related to neural activity. With an understanding of the basic underlying concepts, the way that fMRI is used, and its limitations, are much easier to understand. This 2nd edition includes explanations of new advances in MRI techniques and fMRI data analysis methods, and updated examples of applications of fMRI, including current or future clinical applications. This book is intended for students, researchers, and clinicians, who want to understand the theory and practice of fMRI in sufficient detail to use it for neuroscience research, clinical research, and for clinical practice.