Information integration: its relevance to brain function and consciousness

Abstract

This final contribution further emphasizes that there is no full understanding of cognition without an understanding of consciousness. In fact, consciousness is what makes human cognitive abilities especially sensitive to context and therefore powerful in facing a world having a rich causal structure. Moreover, it argues that the coexistence of functional specialization and functional integration in brain networks – the kind of complexity that allows for the brain’s cognitive prowess and robustness - is precisely responsible for generating consciousness. Below, we briefly revisit the idea that consciousness is a function of a system’s capacity for information integration. We define integrated information as a fundamental quantity associated with every causal mechanism capable of choosing among alternatives, revealing a duality between causation and information. We emphasize that both the quantity and the quality of experience can be accounted for in terms of the information structures or qualia (set of informational relationships) generated by a complex of mechanisms. We briefly discuss how information integration can vary with the spatial and temporal grain size of the interactions within a system, leading to a straightforward definition of emergence. Finally, we consider how a system’s capacity for information integration reflects its ability to match the causal structure of the world, both on the input and the output side. The account below builds upon and extends an approach featured in an earlier article in this journal (Tononi, 2001) and in subsequent articles (Tononi, 2004; Balduzzi and Tononi, 2008; Tononi, 2008; Balduzzi and Tononi, 2009). It concludes with some prospective remarks about the relevance of understanding information integration for analyzing cognitive function, both normal and pathological.