Default mode
Which deep brain structures belong to the default mode network?
Open access · cc by · source: Europe PMC
Resting-state brain scans showed that the default mode network reaches below the cortex into specific thalamic, brainstem and hypothalamic arousal nuclei, while parts of the basal ganglia fluctuate in the opposite direction.
Study at a glance
- Design
- Cross-sectional — Secondary analysis of one 15-minute 7T resting-state fMRI run per person; data were time-aligned across subjects (BrainSync), decomposed into group networks with a tensor method (NASCAR), and the subcortical part of the DMN was quantified in atlas-defined nuclei, with a split-half replication and a seed-based comparison.
- N
- N=168 · 168 healthy Human Connectome Project participants after exclusions, split randomly into two halves of 84 for replication; one post-mortem brainstem specimen was used for tyrosine hydroxylase staining.
- Population
- Healthy young adult volunteers from the Human Connectome Project 7T resting-state release
- Outcome
- Strength and sign of DMN-linked signal in thalamic, brainstem, hypothalamic, basal forebrain and basal ganglia nuclei relative to the cortical DMN
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
Subcortical DMN signal was much weaker than cortical signal overall, but the thalamus, caudate and brainstem reached roughly 30% of cortical strength. As predicted, CL and VTA were significantly more DMN-connected than the thalamus and brainstem on average, and exploratory analyses flagged further thalamic, raphe, reticular and hypothalamic nuclei. The putamen and internal globus pallidus were mostly anti-correlated with the DMN, in line with the proposed mesocircuit in which the pallidum inhibits the central thalamus. The two halves produced almost identical maps (spatial correlation of 0.987).
Methodology
The researchers took high-field (7 tesla) resting-state fMRI from 168 healthy Human Connectome Project volunteers, synchronised everyone's time series, and used a tensor decomposition to find group-level networks spanning cortex and subcortex together. They pulled out the subcortical part of the default mode network (DMN), overlaid it on an ultra-high-resolution post-mortem MRI, and measured it in individual nuclei from several atlases. They tested whether the thalamic central lateral nucleus (CL) and the ventral tegmental area (VTA) were more DMN-connected than their surroundings, explored other nuclei, compared against ordinary seed-based correlation, and repeated everything in two random halves of 84 people.
Limitations
Functional connectivity is correlation, not proof of direct anatomical wiring, and the authors stress that BOLD anti-correlations are not a direct readout of neuronal inhibition, so the mesocircuit is supported but not proven. Subcortical fMRI signal is very noisy and small nuclei are hard to register across people, so the authors warn against voxel-level conclusions; the whole decomposition explained only about 11% of the data's variance. Results come from 7T data in healthy young adults and may not hold on standard 3T clinical scanners or in patients with disorders of consciousness, the group the map is meant to help. Beyond CL and VTA, the extra nuclei are exploratory and hypothesis-generating.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Not yet placed on a claim. This paper has study layers, but no concept page yet cites it as support, challenge, or qualifier.
Related papers in this topic
Same topic cluster — not a recommendation engine.