Efficient Algorithms for Searching the Minimum Information Partition in Integrated Information Theory.

Integrated Information Theory (IIT) links the amount of integrated information (Φ) in the brain to the level of consciousness, proposing that Φ should be measured across the partition of a system where information loss from partitioning is minimized—the Minimum Information Partition (MIP). Exhaustively searching for the MIP is computationally infeasible for large systems. Previous work showed that if a measure of Φ is submodular, an optimization algorithm can find the MIP in polynomial time, but later versions of Φ are not submodular. This study empirically tested the algorithm on non-submodular Φ measures using simulated and real neural data, finding it identifies the MIP nearly perfectly, enabling practical Φ measurement in large systems.

Study at a glance

Abstract

The ability to integrate information in the brain is considered to be an essential property for cognition and consciousness. Integrated Information Theory (IIT) hypothesizes that the amount of integrated information ( Φ ) in the brain is related to the level of consciousness. IIT proposes that, to quantify information integration in a system as a whole, integrated information should be measured across the partition of the system at which information loss caused by partitioning is minimized, called the Minimum Information Partition (MIP). The computational cost for exhaustively searching for the MIP grows exponentially with system size, making it difficult to apply IIT to real neural data. It has been previously shown that, if a measure of Φ satisfies a mathematical property, submodularity, the MIP can be found in a polynomial order by an optimization algorithm. However, although the first version of Φ is submodular, the later versions are not. In this study, we empirically explore to what extent the algorithm can be applied to the non-submodular measures of Φ by evaluating the accuracy of the algorithm in simulated data and real neural data. We find that the algorithm identifies the MIP in a nearly perfect manner even for the non-submodular measures. Our results show that the algorithm allows us to measure Φ in large systems within a practical amount of time.