Deconstructing the default: cortical subdivision of the default mode/intrinsic system during self-related processing

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Brain Imaging

Background:

• The Default Mode network (DM) is a newly identified brain system involved in self-oriented functions.
• The functional homogeneity of the DM remains under investigation, with limited understanding of potential subsystems.

Purpose of the Study:

• To investigate functional subdivisions within the Default Mode network (DM).
• To determine if distinct self-oriented tasks elicit specialized activity within DM nodes, such as the Inferior Parietal Lobule (IPL).

Main Methods:

• BOLD fMRI scans were employed to monitor brain activity.
• Participants recalled self-related positive and negative information across categories (people, food).
• Functional connectivity analysis examined resting-state fluctuations to identify distinct networks.

Main Results:

• Distinct activation regions were observed within the DM in response to different self-oriented tasks.
• The inferior and posterior parietal cortex showed significant subdivisions.
• Functional connectivity analysis confirmed these subdivisions formed distinct networks within the DM.

Conclusions:

• The Default Mode network (DM) is not a unitary system but comprises functionally specialized subregions.
• Findings support the view that the DM, like other cortical areas, is organized into distinct functional subsystems.