  It has been said that complexity lies between order and disorder. In the case
of brain activity, and physiology in general, complexity issues are being
considered with increased emphasis. We sought to identify features of brain
organization that are optimal for sensory processing, and that may guide the
emergence of cognition and consciousness, by analysing neurophysiological
recordings in conscious and unconscious states. We find a surprisingly simple
result: normal wakeful states are characterised by the greatest number of
possible configurations of interactions between brain networks, representing
highest entropy values. Therefore, the information content is larger in the
network associated to conscious states, suggesting that consciousness could be
the result of an optimization of information processing. These findings
encapsulate three main current theories of cognition, as discussed in the text,
and more specifically the conceptualization of consciousness in terms of brain
complexity. We hope our study represents the preliminary attempt at finding
organising principles of brain function that will help to guide in a more
formal sense inquiry into how consciousness arises from the organization of
matter.
