Oxidative metabolism is essential for normal neuronal function. The brain consumes 20% of the oxygen that is used by the body even though it represents only 2% of the total body mass. Most of this oxygen is utilized for the catabolism of glucose and the production of ATP. However, mild to moderate decreases in the availability or utilization of oxygen or glucose impair brain function without reducing the levels of energy metabolites (i.e., ATP).1–4 The cerebral dysfunction that accompanies impaired oxidative metabolism is associated with changes in neurotransmitter metabolism. Thus, an understanding of the pathophysiological basis of altered neuronal function requires knowledge of the relationship of metabolism to neurotransmission.