Correlations in low-frequency BOLD fluctuations reflect cortico-cortical connections

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Functional Neuroimaging

Background:

• Brain regions exhibit spontaneous low-frequency fluctuations (<0.08 Hz) that can be correlated.
• Understanding functional connectivity is crucial for mapping brain networks involved in cognitive tasks.

Purpose of the Study:

• To investigate functional correlations between distant brain regions during a spatial working memory task.
• To compare functional connectivity patterns during task activation versus rest or non-activating tasks.

Main Methods:

• Utilized cross-correlation analysis of low-frequency temporal fluctuations in functional MRI (fMRI) data.
• Examined correlations during continuous performance of a spatial working memory task.
• Compared these correlations to baseline conditions or tasks not directly engaging the network.

Main Results:

• Identified high correlations between the right-hemisphere dorsolateral prefrontal cortex and specific anatomic regions.
• These highly correlated regions showed the largest baseline signal changes in conventional block-design fMRI.
• Functional network correlations increased significantly during the spatial working memory task compared to non-activating tasks.

Conclusions:

• Spatial working memory tasks enhance functional connectivity within specific brain networks, particularly involving the dorsolateral prefrontal cortex.
• Cross-correlation of low-frequency fluctuations is a viable method for mapping task-related functional networks.
• Brain network communication dynamics are modulated by cognitive demands.