Integrated Information in the Spiking-Bursting Stochastic Model.

Integrated information has been recently suggested as a possible measure to identify a necessary condition for a system to display conscious features. Recently, we have shown that astrocytes contribute to the generation of integrated information through the complex behavior of neuron-astrocyte networks. Still, it remained unclear which underlying mechanisms governing the complex behavior of a neuron-astrocyte network are essential to generating positive integrated information. This study presents an analytic consideration of this question based on exact and asymptotic expressions for integrated information in terms of exactly known probability distributions for a reduced mathematical model (discrete-time, discrete-state stochastic model) reflecting the main features of the "spiking-bursting" dynamics of a neuron-astrocyte network. The analysis was performed in terms of the empirical "whole minus sum" version of integrated information in comparison to the "decoder based" version. The "whole minus sum" information may change sign, and an interpretation of this transition in terms of "net synergy" is available in the literature. This motivated our particular interest in the sign of the "whole minus sum" information in our analytical considerations. The behaviors of the "whole minus sum" and "decoder based" information measures are found to bear a lot of similarity-they have mutual asymptotic convergence as time-uncorrelated activity increases, and the sign transition of the "whole minus sum" information is associated with a rapid growth in the "decoder based" information. The study aims at creating a theoretical framework for using the spiking-bursting model as an analytically tractable reference point for applying integrated information concepts to systems exhibiting similar bursting behavior. The model can also be of interest as a new discrete-state test bench for different formulations of integrated information.