The multiplet fractional amount is calculated by the area of each multiplet relative to the total resonance area of the isotopomer as described in the methods section. Overall, the fractional amount of each multiplet in each isotopomer reaches steady state at 150 min with the present infusion protocol, implying brain metabolic equilibrium. Open square: singlet; C2: open circle: doublet12, closed circle: doublet23, diamond: quartet; C3: open circle: doublet, closed square: triplet. C4: open circle: doublet34. For aspartate C3: open circle: doublet23, closed circle: doublet34.