Recent advances in the methodology of magnetic resonance spectroscopy now permit localized proton (1H) spectroscopy of the human brain in clinical magnetic resonance systems. In this study, localized 1H spectroscopy was used to observe directly the stimulation of brain metabolic activity in patients undergoing electroconvulsive therapy (ECT) and to compare results obtained before and after treatments. Persistent increases in lactate were expected on the basis of animal data but these increases were small and equivocal 1 hour after ECT. In contrast, a large increase in a lipid signal from before to after ECT was observed in 5 patients when short echo times were used. We postulate that a significant portion of this lipid signal is related to maximal activation of the phosphatidylinositol system (increased levels of diacylglycerol and free fatty acids) have generalized inhibitory effects potentially relevant to both the clinical pathophysiology of seizures and the efficacy of ECT in major affective disorders.