Changes in connectivity profiles define functionally distinct regions in human medial frontal cortex.

Area of Science:

• Neuroscience
• Brain Imaging
• Cognitive Neuroscience

Background:

• Understanding the relationship between brain structure and function is a core challenge in neuroscience.
• Traditional anatomical landmarks poorly correlate with microstructural boundaries, and cytoarchitecture is not visible in living brains during functional studies.

Purpose of the Study:

• To directly investigate structure-function relationships in the brain using non-invasive imaging techniques.
• To define distinct neocortical regions based on connectivity profiles and identify borders where these profiles change.

Main Methods:

• Utilized diffusion-weighted magnetic resonance imaging (dMRI) and functional magnetic resonance imaging (fMRI) in living subjects.
• Defined brain regions as volumes with similar connectivity patterns, identifying borders by abrupt changes in connectivity profiles.
• Correlated connectivity-defined regions with brain areas activated during tasks specifically engaging the supplementary motor area (SMA) and pre-SMA.

Main Results:

• Identified a distinct border between the supplementary motor area (SMA) and pre-supplementary motor area (pre-SMA) based solely on connectivity profiles, matching expected anatomical locations.
• Demonstrated that the connectivity patterns of the identified SMA and pre-SMA regions corresponded with motor and prefrontal areas, respectively.
• Found strong spatial correlations between regions defined by connectivity and those activated during selective SMA and pre-SMA tasks.

Conclusions:

• Established a strong link between brain structure (defined by connectivity) and function (defined by task-based activation) in the medial frontal cortex.
• Validated a novel strategy using connectivity mapping to delineate functionally distinct brain regions and test structure-function correspondences in other brain areas.