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Cover Picture: ¹³C nuclear magnetic resonance (NMR) spectroscopy of the human brain. The spectroscopic volume of detection was positioned in the occipital parietal lobe of the brain on scout MR images (background image). ¹³C NMR spectra were acquired during an intravenous infusion of [2-¹³C] acetate (right panel), showing ¹³C incorporation into the C2, C3, and C4 atomic positions of glutamate and glutamine. Comparison with spectra acquired during an infusion of [1-¹³C] glucose (left panel) shows clear differences in labeling patterns reflecting cell-type-specific metabolism: acetate and glucose are metabolized primarily in different metabolic compartments in human brain, astroglia, and neurons, respectively. Mathematical modeling of ¹³C incorporation indicates that the glutamate/glutamine neurotransmitter cycle between astroglia and neurons is the major pathway for neuronal glutamate repletion, and that the astroglial TCA cycle flux accounts of ~14% of brain oxygen consumption. For details, see the article by Lebon et al. in this issue (pages 1523-1531).