PET scan studies: It appears there is a default network that becomes active whenever the brain is not specifically occupied and breaks off when the brain has other tasks to attend to. The default network utilizes large amounts of glucose, and more oxygen gram for gram that a beating heart. With strong connections to the hippocampus, it appears to be involved in selectively storing and updating memories. (Fox, Douglas. The Secret Life of the Brain. New Scientist. 2008.)

Stanford University studies: The hippocampus appears to be part of what is now being called the default network of the brain. The activity of the default network is diminished in individuals with Alzheimer’s Disease as compared to the brains of healthy elderly adult controls. It may be that this can be used as an early marker for AD. (Greicius, Michael D., et al. Default-mode network activity distinguishes Alzheimer’s disease from healthy aging: Evidence from functional MRI. CA, 2004.)

The human brain has some default positions, One of those is a tendency to analyze everything in terms of “what does this mean to me?” Examples of defaults:

  • Perception that something you want is growing scarcer (whether or not this is actually occurring)
  • First impressions of other people

(Ornstein, Robert, PhD, and Paul Ehrlich. New World New Mind. p 90-93. MA: Malor Books, 1989, 2000.)