This book illustrates and celebrates recent NMR investigations of brain, identifying its molecular constituents
and following their metabolic activities in vivo. This physical, spectroscopic method is anchored
in its two origins - its present technical methods descended from Bloch and his colleagues and its present
metabolic information derivable from the simple, beautiful NMR experiments on water of Bloembergen,
Purcell and Pound. Water continues as an endlessly fascinating material and in the present volume plays
the central role in MRI and fMRI experiments. From the beginning NMR studies have depended upon
interaction between atomic nuclei and their chemical environment and have been valuable reporters of
these environments. These interactions have been readily interpreted because of two simplifying characteristics
of the NMR phenomena. First spin 12
nuclei of the common elements, e.g. hydrogen, carbon and
phosphorus, interact very weakly with their environment relative to the strong forces they can experience
in available laboratory magnetic fields. Accordingly environmental interactions affecting chemical shifts,
multiplet structure and relaxation times, being weak compared to these Zeman interactions, are perturbations
and as such are readily and quantitatively evaluated. The second simplifying property that allows
reliable information about the nuclei's surroundings is that NMR phenomena, in contrast to most spectroscopic
methods, take place in the ground electronic state, and thereby provide a well-established basis for
interpreting the perturbations by the molecular environment. As a quantitatively understandable measure of
molecules and their interactions NMR has grown continually in these years.