The aerobic brain: lactate decrease at the onset of neural activity

The metabolic events of neuronal energetics during functional activity are still partially unexplained. In particular, lactate (and not glucose) was recently proposed as the main substrate for neurons during activity [Proc Natl Acad Sci USA 91 (1994) 10625] . By means of proton magnetic resonance spectroscopy, lactate was reported to increase during the first minutes of prolonged stimulation Prichard et al 1991 , Sappey-Marinier et al 1992 , Frahm et al 1996 , but the studies reported thus far suffered from low temporal resolution. In the present study we used a time-resolved proton magnetic resonance spectroscopy strategy in order to analyse the evolution of lactate during the early seconds following a brief visual stimulation (event-related design). A significant decrease in lactate concentration was observed 5 s after the stimulation, while a recovering of the baseline was observed at 12 s.