Abstract

between neurons and permit most neuronal-glial interactions in the CNS. Approximately 80 % of all neurons use glutamate, and almost all interneurons use GABA. A third neurotransmitter, NAAG, modulates glutamatergic neurotransmission. Concentration changes in these molecules due to defec-tive synthetic machinery, receptor expression, or errors in their degradation and metabolism are accepted causes of several neurologic disorders. Knowledge of changes in neurotransmitter concen-trations in the brain can add useful information in making a diagnosis, helping to pick the right drug of treatment, and monitoring patient response to drugs in a more objective manner. Recent advances in 1H-MR spectroscopy hold promise in providing a more reliable in vivo detection of these neurotrans-mitters. In this article, we summarize the essential biology of 3 major neurotransmitters: glutamate, GABA, and NAAG. Finally we illustrate possible applications of 1H-MR spectroscopy in neuroscience research. ABBREVIATIONS: AD Alzheimer disease; ALS amyotrophic lateral sclerosis; AMPAR -ami-no-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors; ATP adenosine triphosphate; CNS central nervous system; Cr creatine; EAAT excitatory amino acid transporter; EEG electro-encephalography; 18FDG-PET [18F]fluorodeoxyglucose–positron-emission tomography; GABA -aminobutyric acid; GLAST glutamate/aspartate transporter; 1H-MR proton MR; NAA