New images of a human brain when it regains consciousness from anesthesia show that the more primitive Reptilian complex part of the brain is the first part to awaken. It is often noted that patients struggle when coming out of anesthesia, and this is a good explanation as to why.
As humans developed along evolutionary lines, the brain has has developed and gotten bigger and more complex, but the old formation of the brain is still tucked away underneath the newer neocortex. The R-complex is responsible for the basic functions and emotions, such as aggression, dominance, and territoriality. These basic, instinctual urges are usually suppressed by the neocortex, but since the neocortex does not fire up immediately when coming out of anesthesia it is easy to see why sometimes patients flail and are very aggressive and wary of their surrounding when they awake.
Scientists discussed how when under anesthesia patients lose the ability to be aware of their self and lose self conscious, instead become oblivious to the world around them. This also shows how when under drugs the brain begins to lose control of its more developed parts. These results are all very interesting as people will continue to try and understand exactly how the brain works and how it is able to create a conscious awareness of ones self and the social expectations of those around it.