Functional connectivity maps based on hippocampal and thalamic dynamics may account for the default-mode network.

Area of Science:

• Neuroscience
• Brain Imaging
• Functional Connectivity

Background:

• The default-mode network (DMN) is a widely studied brain network, primarily characterized by its cortical components.
• However, the precise role and contribution of subcortical structures to the DMN remain incompletely understood.
• Existing research often focuses on cortical regions, potentially overlooking subcortical influences.

Purpose of the Study:

• To investigate whether subcortical structures contribute to the neural patterns observed in the default-mode network (DMN).
• To determine if correlation maps derived from subcortical regions align with established DMN activity.
• To clarify the subcortical constituents of the DMN using advanced neuroimaging techniques.

Main Methods:

• Utilized structural and resting-state functional MRI data from 36 participants in the Rockland sample.
• Selected the hippocampus and thalamus as subcortical regions of interest (ROIs).
• Employed seed-based correlation analyses and conjunction analyses comparing PCC-seeded and ROI-based DMN patterns.

Main Results:

• Correlation patterns seeded from the hippocampus, thalamus, and posterior cingulate cortex (PCC) showed significant overlap.
• Combined signals from the thalamus and hippocampus fully accounted for the PCC-seeded DMN.
• Subcortical nuclei like the caudate, putamen, and globus pallidus did not show DMN-similar BOLD signal dynamics.

Conclusions:

• The default-mode network (DMN) encompasses significant subcortical contributions, particularly from the hippocampus and thalamus.
• The DMN may represent integrated limbic and region-specific information processed by interacting neural substrates.
• Neocortical DMN manifestations potentially reflect limbic information within transmodal brain regions.