High-amplitude cofluctuations in cortical activity drive functional connectivity

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Brain Imaging

Background:

• Resting-state functional connectivity (rsFC) is vital for understanding brain organization and developing biomarkers.
• The underlying processes generating correlated brain activity in rsFC remain poorly understood.

Purpose of the Study:

• To decompose rsFC by analyzing moment-to-moment activity cofluctuations.
• To temporally resolve rsFC at the single-frame timescale to link network organization with BOLD signal fluctuations.

Main Methods:

• A temporal unwrapping procedure was employed to analyze rsFC.
• Functional connectivity was resolved at a single-frame timescale, allowing direct comparison with BOLD time series.
• The contribution of high-amplitude cofluctuation frames to overall connectivity and modular structure was assessed.

Main Results:

• A small fraction of high-amplitude cofluctuation frames explains a significant portion of rsFC variance and modular structure.
• These critical frames align with high BOLD activity and show remarkable inter-individual consistency.
• Fluctuations in default mode and control networks were identified as primary drivers of rsFC.
• Cofluctuation amplitude synchronizes across subjects during shared experiences (e.g., movie watching).
• High-amplitude frames contain rich individual-specific information, unlike low-amplitude frames.

Conclusions:

• rsFC possesses fine-scale temporal structure with significant frame-wise variability.
• High-amplitude, consistent activity frames are crucial for establishing rsFC patterns.
• This framework illuminates the relationship between dynamic brain activity and functional connectivity, opening new research avenues.