Multivariate Granger causality unveils directed parietal to prefrontal cortex connectivity during task-free MRI

Area of Science:

• Neuroscience
• Brain Imaging
• Network Science

Background:

• Functional brain connectivity research often overlooks interaction directionality.
• Brain anatomical connections are typically bidirectional, but functional interactions may not be symmetrical.

Purpose of the Study:

• To develop and validate a method for estimating directed brain-brain interactions.
• To investigate the directionality of functional connectivity in the human brain using resting-state fMRI data.
• To explore the implications of directed functional connectivity for understanding brain function.

Main Methods:

• Employed a multivariate Granger Causality-based approach to estimate directed in-network interactions.
• Utilized extensive realistic synthetic BOLD data simulations for method validation, matching Human Connectome Project (HCP) data specifications.
• Applied the developed framework to resting-state fMRI (rs-fMRI) data from the HCP.

Main Results:

• Functional interactions between parietal and prefrontal cortices are asymmetrical, showing directional connectivity from parietal to prefrontal areas.
• These directional effects are primarily localized within the same hemisphere.
• No significant cross-hemispheric functional interactions were observed in terms of directionality.

Conclusions:

• Directed functional connectivity provides crucial information beyond traditional connectivity measures.
• Findings support neurophysiological models where posterior parietal cortices modulate prefrontal regions involved in goal-directed behavior.
• Understanding functional connectivity directionality is vital for interpreting rs-fMRI studies in both healthy and clinical populations.