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Mehrkens, J.-H.

Publications and source records attributed to Mehrkens, J.-H..

2 recordsLinked to original sources

Thalamic oscillations distinguish natural states of consciousness in humans

Natural states of consciousness are thought to be regulated by deep brain structures such as the thalamus. However, very little is known about the underlying electrophysiology in humans. Here, using a rare opportunity to directly record from the human thalamus, we identify a hitherto-unreported brain-state-specific oscillation of approximately 19-45 Hz. This oscillation is present only during Rapid Eye Movement (REM) sleep and wakefulness, while being absent during Non-REM sleep. The 19-45 oscillation further distinguishes REM sleep microstates, co-occurring with bursts of eye movements, and is specific to the Central Thalamus, a structure implicated in causing global brain state transitions. The discovery of a distinct oscillatory signature in the Central Thalamus that distinguishes conscious states opens up avenues to further investigate thalamic contributions to states of consciousness in humans and potentially to refine interventions to treat disorders of consciousness.

neuroscience↗

The human thalamus orchestrates neocortical oscillations during NREM sleep.

A hallmark of non-rapid eye movement sleep is the coordinated interplay of slow oscillations (SOs) and sleep spindles. Traditionally, a cortico-thalamo-cortical loop is suggested to coordinate these rhythms: neocortically-generated SOs trigger spindles in the thalamus that are projected back to neocortex. Here, we used intrathalamic recordings from human epilepsy patients to test this canonical interplay. We show that SOs in the anterior thalamus precede neocortical SOs (peak -50 ms), whereas concurrently-recorded SOs in the mediodorsal thalamus are led by neocortical SOs (peak +50 ms). Sleep spindles, detected in both thalamic nuclei, preceded their neocortical counterparts (peak -100 ms) and were initiated during early phases of thalamic SOs. Our findings indicate an active role of the anterior thalamus in organizing sleep rhythms in the neocortex and highlight the functional diversity of thalamic nuclei in humans. The thalamic coordination of sleep oscillations could have broad implications for the mechanisms underlying memory consolidation.

neuroscience↗