The claustrum is one of the brain’s most intriguing structures: a thin, deeply located sheet of neurons, densely and reciprocally connected with many cortical areas. Because of this connectivity, it has often been discussed as a possible hub for attention, integration, or even consciousness. In this review, in collaboration with the group of Dr. Jesse Jackson at University of Alberta, we propose a more specific and timely perspective: the claustrum may play a key role in synchronized brain states, especially during rest and non-rapid eye movement sleep.
Brain activity is not constant. During movement, exploration, attention, or high cognitive load, cortical activity is typically more desynchronized. By contrast, during quiet rest and sleep, the brain enters more synchronized states, characterized by widespread low-frequency activity. These states are not simply “inactive” periods. They are essential windows during which the brain may reorganize recent experience, coordinate large-scale activity, and support memory consolidation.
The review highlights recent evidence suggesting that claustrum activity increases during these synchronized states, including rest and NREM sleep. Rather than acting as a general “conductor” of the whole brain at all times, the claustrum may be particularly important when cortical networks enter slow, coordinated rhythms. In this context, it may help structure the timing of cortical down states and influence the conditions under which memory traces are replayed, stabilized, and integrated into long-term representations.
This shift in perspective is important. The claustrum is often associated with high-level cognitive functions such as attention, salience, or conscious access. This review suggests that its role may also be understood through the lens of brain states: when the brain is offline from the external world, the claustrum may help coordinate the internal rhythms that allow recent experiences to be processed and consolidated.
A useful way to summarize the idea is that the claustrum may not only help the brain respond to the world; it may also help the brain organize itself when the world is temporarily put on hold.
By bringing together work on claustrum physiology, cortical synchronization, sleep, and memory, this review offers a state-dependent framework for claustrum function. It encourages future studies to consider not only what task an animal or human is performing, but also the ongoing brain state in which claustral activity occurs.
To know more:
- Do, A. D., Portet, C., Goutagny, R., & Jackson, J. (2024). The claustrum and synchronized brain states. Trends in Neurosciences, 47, 1028–1040. https://doi.org/10.1016/j.tins.2024.10.003.