Emergence—how galaxies form or consciousness arises from neurons—lacks formal tools for rigorous study. This article summarizes, elaborates, and extends a recent formal theory of causal emergence based on information decomposition, which is quantifiable and empirically testable. The theory links emergence to information about a system's temporal evolution that cannot be obtained from its parts separately. The article provides an accessible but rigorous introduction to this framework, discussing its merits in various scenarios, interpretation issues, and potential misunderstandings, highlighting the distinctive benefits of this formalism.
The brain balances order and disorder in its activity patterns to adapt to a complex environment. Depression involves excessively rigid, ordered brain states, while psychedelics induce more disordered, overly flexible states. This review uses dynamical system theory and neuroimaging to characterize how different healthy and altered brain states correspond to distinct spacetime dynamics, potentially guiding new treatments for rebalancing brain states in disease.