Intrinsic functional connectivity as a tool for human connectomics: theory, properties, and optimization

Area of Science:

• Neuroscience
• Brain Imaging
• Connectomics

Background:

• Resting state functional connectivity MRI (fcMRI) investigates brain networks via correlated fluctuations.
• fcMRI is constrained by anatomy, enabling characterization of brain system architecture.
• It complements high angular resolution diffusion imaging (HARDI) in human connectomics.

Purpose of the Study:

• To review fcMRI knowledge and explore data reliability and optimization.
• To provide recommendations for optimizing fcMRI acquisition and preprocessing.

Main Methods:

• Six studies (n=98) varied run length, structure, temporal/spatial resolution, and task conditions.
• Preprocessing steps included regression of nuisance signals.
• Data reliability and correlation strengths were assessed across acquisition times.

Main Results:

• Moderate to high test-retest reliability was observed.
• Run structure, temporal, and spatial resolution had minimal influence.
• Fixation and eyes-open rest conditions yielded stronger correlations.
• Correlation estimates stabilized with acquisition times as short as 5 minutes.
• Nuisance signal regression effectively minimized nonspecific correlations.

Conclusions:

• fcMRI is a robust and brief tool for large-scale brain architecture and genetic influence studies.
• It has complementary strengths when combined with HARDI for human connectomics.
• Recommendations for optimizing fcMRI acquisition and analysis are provided.