I have included the parts of the brain that are active, mainly consuming Oxygen at which time the subjects are in a state of awake, eyes closed, restful waking. Images are a sort of average over many individual subjects. The red areas are mostly in the midline in the front of the brain, the Medial prefrontal cortex and in the back of the brain posterior cingulate gyrus and Precuneus in the midline, and the right and left angular gyrus of the parietal lobe. Even without knowing exactly where these areas are in the brain they constitute a network of brain regions working together.
Active areas are signified here in fMRI in red which means they extract Oxygen in preference to other brain areas. The subjects were at rest, not working on any external problem and had their eyes closed. This situation is similar to the EEG lab, restful waking eyes closed.
Now here is an important point. When the subject opens eyes specifically looking at something, or if involved in a task such as trying to find the solution to a problem, the Default mode network is liable to switch off in favor of other regions of brain that take over and become active. Therefore the imaging beautifully defines a type of inactive waking by becoming less active performing a specific task. So the Default Mode Network is as much defined by diminished activity in task related behavior as it is by the red areas of activity during undirected rest.
You can see this on the scans but on the EEG too as soon as a subject opens his eyes the amplitude of alpha on the EEG, which is most visible in the visual part of the brain, markedly decreases. So the alpha EEG resembles PET and fMRI as well.
Most people work for ‘the man,’ your boss, the system, all day. Then you come home and your brain, remaining nominally awake, wants to turn off and ‘watch’ television or do something unproductive. Some who might be called lazier people among us like this off time. Some focussed people, Elon Musks and Thomas Edisons remain intensely focused, always solving problems. Who’s experiencing more, accomplishing more, burning more calories? More on this later.
