Evidence for quasicritical brain dynamics

TL;DR

This paper proposes that brain cortex operates near a quasicritical state, explaining variability in critical exponents across conditions while maintaining dynamical scaling relations, supported by simulations and experimental data.

Contribution

It introduces the theory of quasicriticality as an organizing principle for brain dynamics, accounting for observed variability in critical exponents.

Findings

Exponents decrease along the Widom line with external stimuli.

Dynamical scaling relations approximately hold despite exponent variability.

Simulations and experimental data support the quasicriticality model.

Abstract

Much evidence seems to suggest cortex operates near a critical point, yet a single set of exponents defining its universality class has not been found. In fact, when critical exponents are estimated from data, they widely differ across species, individuals of the same species, and even over time, or depending on stimulus. Interestingly, these exponents still approximately hold to a dynamical scaling relation. Here we show that the theory of quasicriticality, an organizing principle for brain dynamics, can account for this paradoxical situation. As external stimuli drive the cortex, quasicriticality predicts a departure from criticality along a Widom line with exponents that decrease in absolute value, while still holding approximately to a dynamical scaling relation. We use simulations and experimental data to confirm these predictions and describe new ones that could be tested soon.