Hierarchical organization of critical brain dynamics

TL;DR

This study investigates how signatures of criticality in neuronal activity vary systematically along the brain's anatomical hierarchy, revealing a complex, measure-dependent organization linked to brain structure and function.

Contribution

It applies renormalization group methods to large-scale neuronal data, uncovering non-uniform, measure-dependent criticality signatures that relate to brain hierarchy and task engagement.

Findings

Criticality signatures vary systematically along the anatomical hierarchy.

Different criticality exponents show inconsistent gradients, indicating measure-dependent organization.

Correlations among criticality markers can reconstruct brain hierarchy during active tasks.

Abstract

The hierarchical organization of the brain is a fundamental structural principle, while brain criticality is a leading hypothesis for its collective dynamics. However, the connection between structure and signatures of criticality remains an open question. Here, we address this issue by applying phenomenological renormalization group approaches to large-scale neuronal spiking activity from the mouse visual cortex and hippocampus. We find that signatures of criticality are not uniform, but instead vary systematically along the known anatomical hierarchy in both brain systems. Strikingly, the direction along this gradient is inconsistent across different criticality exponents, revealing a nontrivial, measure-dependent organization: exponents based on static properties point to a gradient in one direction, while the exponent based on dynamic properties points in the opposite direction. Moreover, the signatures across the visual system are strongly modulated by the engagement in a visual task. We show that the correlations among criticality markers of different brain regions during active engagement are sufficient to reconstruct the anatomical hierarchy from the dynamics. Scaling exponents closely follow a theoretically predicted scaling relation among them, and covary with the hierarchical position. Our findings provide a direct link between the collective dynamics of neurons and the macroscopic architecture of the brain.