That you're satisfied with the definition supplied astounds me. The words are loose as can be. Amoebae integrate information and produce behavior reflecting the actions of a unified singular system insofar as those undefined words mean anything.

Somehow unknowable indeed. "While neuroscience might shed light on the input and output functions of the brain, the quantification for integrated information we have presented here implies that it will be unable to shed light on the complex tangle that is core consciousness."