Human cortex organizes dynamic co-fluctuations along sensation-association axis

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• The human brain's functional organization relies on coordinated neural fluctuations.
• Understanding how these large-scale co-fluctuations transition across different amplitude levels is crucial but remains largely unknown.

Purpose of the Study:

• To investigate the principles governing amplitude-dependent transitions of functional brain network interactions.
• To introduce a novel metric, the co-fluctuation score, for quantifying these dynamic reorganizations.

Main Methods:

• Utilized resting-state functional magnetic resonance imaging (fMRI) data.
• Introduced and applied a "co-fluctuation score" to analyze instantaneous functional interactions relative to global amplitude dynamics.
• Examined data across multiple independent samples, including high-resolution 7T fMRI.

Main Results:

• Identified distinct amplitude-dependent co-fluctuation states aligned with the sensorimotor-association (SA) axis.
• Sensorimotor networks dominated high-amplitude states, associative systems thrived in intermediate amplitudes, and limbic systems engaged in low-amplitude states.
• Observed developmental refinement of this hierarchy from childhood to adulthood and adaptive reconfiguration under external stimuli.

Conclusions:

• The sensorimotor-association (SA) axis serves as a fundamental organizational principle for amplitude-dependent brain network transitions.
• The brain dynamically balances external processing (high-amplitude) with internal cognition/emotion (mid-to-low amplitude) via amplitude-stratified interactions.
• This framework integrates transient coordination with stable functional architecture, offering insights into brain dynamics across development and in response to stimuli.