MRSI in mice reveals changes in glutamate and lactate levels in somatosensory brain areas elicited by electric hindpaw stimulation. Using increasing stimulus amplitudes, lactate signals consistently decreased with increasing stimulus strength. This surprising result might reflect accelerated lactate clearance triggered by a generalized CBF increase in response to hindpaw stimulation, previously observed in this species. In contrast to mice, Lac levels in the contralateral somatosensory cortex of rats significantly increased with stimulus amplitude reflecting increased glycolytic activity and no obvious indication of increased lactate clearance. Despite the difference in Lac responses, similar Glu responses have been observed in both species.