Last Updated on September 12, 2025
During sleep and quiet rest, the neocortex generates large-scale slow-wave (SW) activity. These synchronized rhythms suggest the presence of a network capable of coordinating inhibitory interneurons across brain regions. But which structure enables this coordination?
For years, neuroscientists have suspected the claustrum, a thin, sheet-like structure with widespread cortical connections, could be the key. A landmark study from the Yoshihiro Yoshihara lab at the RIKEN Center for Brain Science (Nature Neuroscience, 2020) sought to answer this question directly. Their findings reveal the claustrum as a central driver of synchronous neocortical slow waves.
Why Studying the Claustrum Is Challenging
The claustrum’s deep location and intricate connectivity make it difficult to study. Traditional tethered EEG systems add further limitations:
Restricted animal behavior – long cables tangle, restrict movement, and disrupt social interactions.
Signal noise – the tether acts as an antenna, introducing motion artifacts and environmental interference.
Limited scalability – multiple tethered animals in one cage increase tangling risk and data loss.
These issues make it difficult to measure large-scale brain synchronization accurately.
A Wireless EEG Approach to Claustrum Research
To overcome these barriers, researchers turned to the ELG-2 Datalogger Wireless EEG system, which records EEG, EMG, and local field potentials (LFPs) in freely moving mice.
The lightweight headstage connects directly to implanted electrodes and stores data on a microSD card, enabling researchers to:
Record without motion artifacts.
Monitor multiple mice simultaneously.
Preserve natural behaviors such as sleep and social interaction.
Combined with genetic tools, this approach allowed the team to create a claustrum-specific Cre-expressing mouse line, making it possible to visualize, manipulate, and record activity from claustral glutamatergic neurons.
Study Design at a Glance
Genetic model: Claustrum-specific Cre line for targeted manipulation.
Electrodes: Implanted in prefrontal, cingulate, and parietal cortex for LFP; parietal cortex for EEG; neck muscle for EMG.
Experimental groups: Claustrum-ablated mice (Cre-dependent diphtheria toxin) vs. GFP controls.
Recording conditions: Freely moving mice under a 12h light/dark cycle, acclimated with dummy head stages before experiments.
Key Findings
- Connectivity: Claustrum neurons showed widespread reciprocal connections with multiple cortical regions.
- Cellular activity: Optogenetic stimulation of claustral neurons drove excitatory inputs, strongly activating inhibitory interneurons.
- Behavioral states: In vivo EEG revealed claustral neurons were more active during slow-wave periods than during other brain states.
- Loss-of-function: Ablating claustral neurons dramatically reduced synchronized slow-wave activity during both sleep and quiet rest.
Together, these results demonstrate that the claustrum is essential for coordinating cortical slow-wave activity across the brain.
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Wirelessly recording EEG in freely moving animals has unlocked numerous possibilities for discoveries in sleep, seizure, and other neurological disorder research studies. This has previously been limited to tethered recording systems, which can alter animal behavior and add noise to data.
Why This Matters for Neuroscience
For researchers studying sleep, consciousness, or neural circuits, this study demonstrates that:
The claustrum is not just connected, but essential for synchronizing brain rhythms.
Wireless EEG in freely moving animals overcomes the limits of tethered systems.
Combining genetic tools and wireless recording enables new circuit-level discoveries.
About the ELG-2 Wireless EEG System
The ELG-2 Wireless EEG system is designed for neuroscience research in rodents, offering:
4–7 customizable recording channels (EEG, EMG, LFP)
Lightweight, removable headstage for animal comfort
Direct-to-microSD storage for interference-free data
Flexible electrode configurations to match study design
By reducing artifacts and removing behavioral restrictions, ELG-2 helps researchers achieve reproducible, high-quality data in naturalistic conditions.
Reference
Narikiyo, K., Mizuguchi, R., Ajima, A., Shiozaki, M., Hamanaka, H., Johansen, J.P., Mori, K., Yoshihara, Y. (2020). The claustrum coordinates cortical slow-wave activity. Nature Neuroscience, 23(6), 741–753. doi:10.1038/s41593-020-0625-7
FAQs
What is the claustrum?
The claustrum is a thin sheet of neurons beneath the neocortex with widespread cortical connections. It has been described as one of the most interconnected brain regions, possibly serving as a hub for synchronizing activity. For an overview, see this review of the claustrum and this anatomical perspective.
How did researchers record claustrum slow-wave activity?
They combined a claustrum-specific transgenic mouse line with wireless EEG and optogenetics to record and manipulate activity in vivo.
Why use wireless EEG instead of tethered systems?
Wireless EEG avoids cable tangling, motion artifacts, and behavior restrictions — enabling accurate, scalable, and naturalistic neuroscience experiments.