Collapse of local circuit integrated information Φ during NREM sleep

Clarifying the mechanisms underlying the emergence of consciousness remains a fundamental challenge in modern neuroscience. Integrated Information Theory (IIT) provides a mathematical framework derived from the phenomenological properties of consciousness as its axioms. IIT proposes that consciousness is identical to a system’s intrinsic cause-effect information structure, quantified by integrated information Φ. While IIT predicts that the Φ of a neuronal system should decrease during the loss of consciousness, this hypothesis has remained untested at the neural circuit level. The present study provides empirical support for this IIT prediction. It was found that Φ within local circuits decreases during non-rapid-eye-movement (NREM) sleep compared to wakefulness and REM sleep, independent of cortical laminar structure or firing rates or regions. The reduction in Φ was particularly pronounced during off-periods, when neural activity is collectively suppressed. These results imply that consciousness is an information structure that cannot be reduced to the properties of individual system elements (such as firing rates), and that its collapse is fundamentally linked to the loss of consciousness. The findings provide critical empirical support for IIT as a mathematical theory aiming to explain conscious experiences.