Mapping the subcortical connectivity of the human default mode network

Area of Science:

• Neuroscience
• Neuroimaging
• Computational Neuroscience

Background:

• The default mode network (DMN) is crucial for self-awareness and consciousness.
• Restoring consciousness in brain injury patients often targets subcortical areas linked to the DMN.
• Subcortical DMN connectivity is not fully mapped, hindering identification of optimal therapeutic targets.

Purpose of the Study:

• To create a comprehensive map of default mode network (DMN) subcortical connectivity.
• To identify optimal subcortical targets for neuromodulation therapies aimed at restoring consciousness.
• To advance understanding of the neural basis of human consciousness.

Main Methods:

• Utilized 7 Tesla resting-state functional MRI (rs-fMRI) data from 168 healthy volunteers (Human Connectome Project).
• Employed advanced signal processing, including BrainSync for temporal synchronization and a novel Nadam-Accelerated SCAlable and Robust (NASCAR) tensor decomposition method.
• Integrated functional data with high-resolution ex vivo MRI for neuroanatomic analysis of brainstem, thalamus, hypothalamus, basal forebrain, and basal ganglia.

Main Results:

• The NASCAR method revealed strong correlations between DMN activity and the central lateral nucleus of the thalamus and ventral tegmental area.
• Exploratory analysis identified correlations with median and dorsal raphe, lateral hypothalamus, and caudate nuclei.
• Negative correlations were found with the putamen and globus pallidus, supporting the mesocircuit hypothesis of consciousness.

Conclusions:

• The study provides a detailed map of DMN subcortical connectivity, advancing our understanding of consciousness.
• Identified specific subcortical regions (e.g., thalamus, ventral tegmental area) as strongly connected to the DMN.
• The findings can guide the selection of therapeutic targets for disorders of consciousness in clinical trials.