This paper by Raichle et al. explores the concept of a default mode of brain function, which is defined as a baseline state of the brain that is activated when specific goal-directed behaviors are not in play. The authors use the brain oxygen extraction fraction (OEF) to identify this baseline state, which is uniform in the awake but resting state, such as lying quietly with eyes closed. They find that areas of deactivation, primarily in extrastriate visual cortices, exhibit increases in OEF, suggesting that these areas are more active when the eyes are open. The study also highlights the importance of midline areas like the posterior cingulate and medial prefrontal cortex (MPFC) in maintaining a default state of brain activity, which may involve continuous information gathering and evaluation. The findings suggest that these areas may play a crucial role in attention and awareness, and that their activity is attenuated during focused attention or goal-directed tasks.This paper by Raichle et al. explores the concept of a default mode of brain function, which is defined as a baseline state of the brain that is activated when specific goal-directed behaviors are not in play. The authors use the brain oxygen extraction fraction (OEF) to identify this baseline state, which is uniform in the awake but resting state, such as lying quietly with eyes closed. They find that areas of deactivation, primarily in extrastriate visual cortices, exhibit increases in OEF, suggesting that these areas are more active when the eyes are open. The study also highlights the importance of midline areas like the posterior cingulate and medial prefrontal cortex (MPFC) in maintaining a default state of brain activity, which may involve continuous information gathering and evaluation. The findings suggest that these areas may play a crucial role in attention and awareness, and that their activity is attenuated during focused attention or goal-directed tasks.