A default mode of brain function
Proceedings of the National Academy of Sciences January 16, 2001 Marcus E. Raichle, Ann Mary MacLeod, Abraham Z. Snyder et al. 12,440 citations
A baseline state of the normal adult human brain is identified in terms of the brain oxygen extraction fraction (OEF), the ratio of oxygen used to oxygen delivered by blood flow. In the awake but resting state (lying quietly with eyes closed), the OEF is remarkably uniform across the brain. Local deviations in OEF underlie functional MRI signals of changes in neuronal activity. Using PET measurements, all significant deviations from the mean hemisphere OEF were increases, indicating deactivations, almost exclusively in the visual system. These findings suggest an organized, baseline default mode of brain function that is suspended during goal-directed behaviors.