In the last decade of this millennium, while, on the one hand, the international scientific community has focused with increasing endeavour on the research about the great unknowns of the mechanisms and the pathologies of the human brain, on the other hand, the NMR community has achieved some important results, which should widely affect, in the future, the possibility of understanding the function and disfunction of the human brain.

In the early 1980s, the beginning of the application of Magnetic Resonance Imaging (MRI) to the morphological study of the brain in vivo, has played an extraordinary role, which, since then, placed MRI in a leading position among the methodologies used for investigation and diagnostics of the Central Nervous System.

In the 1990s, the objective of finding new means based on MRI capable of giving functional and metabolic information, with the highest possible space resolution, drove the scientists towards different approaches. Among these, the first one to generate a breakthrough in the localization of specific cerebral functions was the Blood Oxygen Level Dependent (BOLD) MRI. A very wide range of applications followed the discovery of BOLD imaging. Still, this method gives an indirect information of the localization of functions, via the variation of oxygen release and deoxyhemoglobin formation. Of course, a high-resolution spatial distribution of the metabolites, crucial to brain function, would give a deeper insight into the occurring processes. This finality is aimed at by the Double Magnetic Resonance methods, which are developing new procedures, able to detect some metabolites with increasing sensitivity and resolution. A third new promising approach to functional MRI should derive from the use of hyperpolarized gases like xenon. In fact xenon is soluble in blood and capable of getting bound to hemoglobin and albumin; these preliminary features, together with its very intense NMR signal, when hyperpolarized, opens a series of potential applications to the study of brain function.

These three new methods, BOLD MRI, Double Resonances and Hyperpolarized Gases, were widely proposed by the lecturers in this Varenna Course; thus, this book contains the widest and deepest presentation of these fields. The Course was intended for people who mean to work at the development of these areas, i. e. for physicists, chemists, engineers, etc., but wide openings, to the biomedical aspects of brain function and disfunction in connection to the potentialities of NMR, were also made. I therefore believe that this book, made by the contributions of some of the leading scientists in this research area, represents an original and crucial tool for those who want to investigate by NMR the fascinating world of the human brain function.

B. Maraviglia