In recent years, the neurosciences have opened up new insights into the functioning of the brain as well as previously unknown possibilities for targeted intervention in its functions through expanded methods and research approaches. This not only opens up opportunities for better treatment of diseases. New approaches to influencing brain functions with drugs and the development of brain-machine interfaces bring the prospect of increasing and expanding human abilities within reach - with hardly foreseeable social consequences. Moreover, our self-image as responsibly acting and freely deciding persons is challenged by the theses of some leading neuroscientists. Are mental processes, as they claim, merely the reflex of neuronal events and is our freedom of will only an illusion created by the brain? This volume works through the state of the scientific debate on the most important neuroscientific fields of work and provides a comprehensive overview of the explosive questions that brain research raises for present and future society.