In recent years, the brain's “default network”, a set of regions characterized by decreased neural activity during goal-oriented tasks, has generated a significant amount of interest, as well as controversy. Much of the discussion has focused on the relationship of these regions to a “default mode” of brain function. In early studies, investigators suggested that, the brain's default mode supports “self-referential” or “introspective” mental activity. Subsequently, regions of the default network have been more specifically related to the “internal narrative,” the “autobiographical self,” “stimulus independent thought,” “mentalizing,” and most recently “self-projection.” However, the extant literature on the function of the default network is limited to adults, i.e., after the system has reached maturity. We hypothesized that further insight into the network's functioning could be achieved by characterizing its development. In the current study, we used resting-state functional connectivity MRI (rs-fcMRI) to characterize the development of the brain's default network. We found that the default regions are only sparsely functionally connected at early school age (7–9 years old); over development, these regions integrate into a cohesive, interconnected network.
(abstract fra: The maturing architecture of the brain's default network, af Damien A. Fair,*† Alexander L. Cohen,‡ Nico U. F. Dosenbach,‡ Jessica A. Church,* Francis M. Miezin,*‡ Deanna M. Barch,‡§¶ Marcus E. Raichle,*†‡‖Steven E. Petersen,*‡§‖ and Bradley L. Schlaggar*†‡‖)
We have arrived at the following provisional conclusions. The mind itself is unconscious , but we percieve it conciously by looking inwards. It is this capacity for "looking inwards" (for introspection and self-awareness) that is the most essential property of the mind. The "me" that we percieve through introspection can also be percieved through our external senses as a physical body.
Although it is not neessecary to be conscious of the external environment in order to percieve it, it is nevertheless usefull. It is usefull to be able to say things like: "I feel like this (hungry) so I want to eat that thing over there," og, "I feel like this (upset)), because that thing over there bite me." In this way, consciousness - that is, value - is imparted to objects, and objects come to be known as "good" or "bad".
Consciousness consists of awareness of what is happening around us, grounded in a background medium of self-awareness.