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Exploring Deep Magnetoencephalography via Thalamo-Cortical Sleep Spindles
Gregory F Rattray1, Hugo R Jourde1, Sylvain Baillet2
1Department of Psychology, Concordia University, Quebec, Canada.
Human Brain Mapping
|September 26, 2025
Summary
Magnetoencephalography (MEG) functional connectivity successfully resolved deep brain networks, including the thalamus, during sleep spindles. This non-invasive method advances the study of subcortical brain region functions.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- Subcortical brain regions, such as the thalamus, are crucial for sensory and cognitive functions.
- Magnetoencephalography (MEG) offers high temporal resolution for studying brain networks, but its ability to resolve deep sources like the thalamus is uncertain.
- Functional connectivity (FC) methods can improve source differentiation but are rarely applied beyond cortical regions.
Purpose of the Study:
- To investigate the feasibility of resolving deep brain sources, specifically the thalamus, using MEG functional connectivity patterns.
- To leverage thalamo-cortical sleep spindles and spindle-free non-rapid eye movement (NREM) sleep periods to assess connectivity.
- To explore the application of graph theory in identifying network hubs within thalamo-cortical networks.
Main Methods:
- Simultaneous MEG and electroencephalography (EEG) recordings were obtained from 19 participants during a 2-hour nap.
- Sleep spindle and non-spindle periods were identified, and connectivity was assessed using coherence and imaginary coherence.
- Graph theory analysis was employed to determine network hubs and contributions of different brain regions.
Main Results:
- Functional connectivity significantly increased during sleep spindles within a distributed thalamo-cortical-hippocampal network.
- MEG-based functional connectivity patterns differentiated between small thalamic nuclei, though metric choice influenced results.
- Graph theory revealed distinct cortical, thalamic, and hippocampal roles in fast (13-16 Hz) and slow (10-13 Hz) sigma-band connectivity.
Conclusions:
- MEG functional connectivity can non-invasively resolve deep brain networks, including the thalamus, during NREM sleep and sleep spindles.
- This methodology enables the study of subcortical region functions in healthy humans.
- Findings provide methodological guidance for future research designs and interpretations in neuroimaging studies of deep brain structures.
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