The Dana site has a good little article by Jim Schnabel on the search for neural correlates of consciousness why it is difficult? Some of those trying and how? (here). I recommend reading the article for a simple explanation of how the experiments are done.
But there are other interesting bits. Below is a very clear description of nonconscious and conscious activity. This is the process that the researchers are trying to explore in more detail.
Essentially, they found that during nonconscious perception, activity occurred in multiple areas of the cortex, yet never became coherentfiring in syncover large distances; this nonconscious activity also dissipated relatively quickly.
By contrast, during conscious perception the activity was able to ignite into much longer-term, self-reinforcing, interconnected activity across widely separated cortical areas. This coherent activity included areas of the prefrontal cortex and appeared to be concentrated in the gamma wave range of frequencies, which previous research has linked to attention and consciousness.
Another interesting part of the article is reference to Koch’s take on Tononi’s theory:
Among possible explanations, Koch tentatively favors the Information Integration theory of consciousness put forward by neuroscientist Giulio Tononi at the University of Wisconsin. Tononi proposes that consciousness is a fundamental property arising from any system that uses interdependent, information-exchanging parts. By this logic, the most powerful consciousness-generating networks of the brain would be those that integrate the largest amount of neural activityas the results from Naccache and colleagues also suggest.
The theory implies, however, that consciousness is not limited to highly evolved animals or even to biological brains. As Koch puts it, Whether its my iPhone or the flatworm C. elegans or the human brain, it would differ only in the amount of consciousness. But all would be conscious.