Biology subjects

Schreiner, T.

Publications and source records attributed to Schreiner, T..

15 recordsLinked to original sources

bioRxiv2026

The breathing cycle gates memory reactivation during human NREM sleep

Sleep-dependent memory consolidation relies on the precise coordination of slow oscillations (SOs) and spindles. Respiration has recently emerged as a potential pacemaker of this coordination, but whether it thereby shapes memory processes during sleep remains unknown. Here, we used closed-loop targeted memory reactivation (TMR) in humans (N = 25) to target auditory cues to either each participants SO-spindle-favored respiratory phase (preferred-phase cueing) or the opposite phase (antiphase cueing). Preferred-phase cueing enhanced associative memory relative to antiphase cueing and promoted more precise spindle alignment to SO up-states. Respiratory phase also shaped the timing of reactivation: preferred-phase cues aligned category-specific reactivation with the ensuing SO up-state, whereas antiphase cues delayed reactivation to later SO-spindle complexes occurring at a similar respiratory phase. These findings identify breathing as an endogenous timing signal that organizes the SO-spindle windows in which memory reactivation unfolds, thereby structuring sleep-dependent consolidation.

neuroscience↗

bioRxiv2026

Non-invasive tracking of ripple-like activity during human sleep using MEG

Hippocampal ripples are considered a key mechanism of sleep-dependent memory consolidation. In humans, however, their direct investigation has relied on invasive recordings from patients with epilepsy, because EEG provides limited access to fast activity from deep medial temporal structures. Here, we tested whether source-resolved magnetoencephalography can reveal physiologically meaningful ripple-like activity during NREM sleep in healthy humans. These events showed hallmarks expected of sleep ripples: they were most prominent in medial temporal regions and embedded within slow oscillation (SO)-spindle dynamics, occurring preferentially during SO up-states and spindle centers. To test mnemonic relevance, we combined sleep MEG with targeted memory reactivation, in which learning cues were replayed during sleep. TMR improved memory performance, and later remembered cues preferentially recruited medial temporal ripple-like events alongside cortical spindles. Ripple-like events also coincided with enhanced item-specific reactivation during successful TMR. Together, these findings establish MEG as a non-invasive window onto hippocampo-cortical memory dynamics during sleep.

neuroscience↗

bioRxiv2026

Sequential coupling of sleep oscillations enables concept-neuron reactivation and supports information flow across the human hippocampal-cortical circuit

Effective memory consolidation during sleep is thought to rely on the transfer of reactivated memory traces from the hippocampus to the cortex. However, the mechanisms supporting this essential dialogue across brain areas remain poorly understood. Here, we recorded single-neuron activity (n = 1097) in the medial temporal lobe (MTL) of 10 epilepsy patients across 21 nights of sleep. Before sleep, patients engaged in a memory task with stimuli eliciting concept-neuron responses. During non-rapid eye movement (NREM) sleep, neuronal firing locked to sharp wave-ripples (SWR) revealed a directed flow of information from the hippocampus to cortical targets. Notably, within SWR-driven activity, experience-dependent concept neurons exhibited elevated co-activation both within and across MTL regions, indicating selective reactivation of behaviorally relevant information. Cross-regional co-activation of concept cells was markedly enhanced when hippocampal SWRs coincided with cortical slow oscillation-spindle complexes, suggesting an active role of the cortex in shaping interregional communication. These findings provide evidence that SWRs in humans selectively reactivate experience-related neural ensembles across the hippocampal-cortical network, while synergistic interactions with cortical slow oscillation-spindle events might facilitate effective memory consolidation.

neuroscience↗

bioRxiv2025

Respiratory coordination of excitability states across the human wake-sleep cycle

While the respiratory rhythm is increasingly recognized as a key modulator of oscillatory brain activity across the wake-sleep cycle in humans, very little is known about its influence on aperiodic brain activity during sleep. This broadband activity indicates spontaneous fluctuations in excitation-inhibition (E:I) balance across vigilance states and has recently been shown to systematically covary across the respiratory cycle during waking resting state. We used simultaneous EEG and respiratory recordings over a full night of sleep collected from N = 23 healthy participants to unravel the nested dynamics of respiration phase-locked excitability states across the wake-sleep cycle. We demonstrate a prominent phase shift in the coupling of aperiodic brain activity to respiratory rhythms as participants were transitioning from wakefulness to sleep. Moreover, respiration-brain coupling became more consistent both across and within participants, as interindividual as well as intraindividual variability systematically lessened from wakefulness and the transition to sleep towards deeper sleep stages. Our results suggest that respiration phase-locked changes in E:I balance conceivably add to sleep stage-specific neural signatures of REM and NREM sleep, highlighting the complexity of brain-body coupling during sleep.

neuroscience↗

bioRxiv2025

Respiration shapes the neural dynamics of successful remembering in humans.

Respiration has been shown to impact memory retrieval, yet the neural dynamics underlying this effect remain unclear. Here, we investigated how respiration shapes both behavioral and neural expressions of memory retrieval by re-analyzing an existing dataset where scalp electroencephalography and respiration recordings were acquired while participants (N = 18) performed an episodic memory task. Our results unveil that respiration influences retrieval-related power fluctuations in the /{beta} band and concomitant memory reactivation. Specifically, we found that both key neural signatures of successful remembering were co-modulated during exhalation, with the strength of the interaction between respiration and reactivation processes being associated with memory performance. Together, these findings suggest that respiration may act as a scaffold for episodic memory retrieval in humans by coordinating the neural conditions that support effective remembering. Significance statementRecent evidence suggests that respiration may shape neural dynamics underlying various cognitive processes. In this study, we identify respiration as a potential pacemaker for memory retrieval by showing that key neural signatures of effective remembering--namely, decreases in /{beta} power and the reactivation of previously encoded neural representations--are tightly synchronized with the respiratory cycle. Notably, the strength of this respiration-brain coupling is associated with individual memory performance, underscoring the critical role and functional significance of brain-body interactions in supporting cognitive functions.

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bioRxiv2025

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↗

bioRxiv2025

Theta oscillations dictate the evolution of memories across periods of sleep or wakefulness

How does the brain select which experiences to consolidate into long-term memory? Numerous neurobiological frameworks suggest that certain memories are "tagged" at learning for consolidation during later sleep. However, experimental evidence of such a tagging mechanism in the human brain is lacking. Using electroencephalography in humans, we reliably differentiate brain states for memories that are tagged at learning for consolidation across sleep or wakefulness. The tagging of memories for consolidation across sleep (but not wakefulness) was linked to 3-8Hz theta rhythms during learning. The magnitude of this tagging-related theta response predicted the coupling of slow oscillations to sleep spindles during post-learning sleep (an established neural correlate of sleep-dependent memory processing). In turn, slow oscillation-spindle coupling was associated with better memory performance at the post-sleep test. These findings provide new insights into the neural mechanisms through which our brains determine which information is retained for the future.

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bioRxiv2023

Respiration shapes sleep-oscillations and memory reactivation in humans.

The beneficial effect of sleep on memory consolidation relies on the precise interplay of slow oscillations (SOs) and spindles. However, whether these rhythms are orchestrated by an underlying pacemaker has remained elusive. Here, we tested whether respiration, which has been shown to impact brain rhythms and cognition during wake, shapes memory reactivation by modulating sleep-related oscillations and their interplay in humans. We recorded scalp EEG and respiration throughout an experiment in which participants acquired associative memories before taking a nap. Our results reveal that respiration strongly modulates the emergence of sleep oscillations. Specifically, SOs, spindles as well as their interplay (i.e., coupled SO_spindle complexes) systematically increase towards inhalation peaks. Moreover, the strength of respiration-SO_spindle coupling is linked to the extent of memory reactivation during SO_spindles. Our results identify respiration as a potential pacemaker for memory consolidation in humans and highlight the critical role of brain-body interactions during sleep.

neuroscience↗

bioRxiv2023

Memory reactivation of real-world spatial orientation revealed by human electrophysiology.

Memory consolidation relies on the reactivation of previous experiences during sleep. The precise interplay of sleep-related oscillations (slow oscillations, spindles and ripples) is thought to coordinate the information flow between relevant brain areas, with ripples mediating memory reactivation. However, in humans empirical evidence for a role of ripples in memory reactivation is lacking. Here, we investigated the relevance of sleep oscillations and specifically ripples for memory reactivation during human sleep using targeted memory reactivation (TMR). Intracranial electrophysiology in epilepsy patients and scalp EEG in healthy participants revealed that elevated levels of SO-spindle activity promoted the read-out of TMR induced memory reactivation. Importantly, spindle-locked ripples recorded intracranially from the medial temporal lobe were found to be instrumental for memory reactivation to unfold during non-rapid eye movement (NREM) sleep. Our findings establish ripples as key-oscillation in human systems consolidation and emphasize the importance of the coordinated interplay of the cardinal sleep oscillations.

neuroscience↗

bioRxiv2023

Electrophysiological signatures of veridical head direction in humans

Information about heading direction is critical for navigation as it provides the means to orient ourselves in space. However, given that veridical head direction signals require physical rotation of the head and most human neuroimaging experiments depend upon fixing the head in position, little is known about how the human brain is tuned to such heading signals. To address this, we asked fifty-two healthy participants undergoing simultaneous EEG and motion tracking recordings (split into two experiments) and ten patients undergoing simultaneous intracranial EEG and motion tracking recordings to complete a series of orientation tasks in which they made physical head rotations to target positions. We then used a series of forward encoding models and linear mixed-effects models to isolate electrophysiological activity that was specifically tuned to heading direction. We identified a robust posterior central signature that predicts changes in veridical head orientation after regressing out confounds including sensory input and muscular activity. Both source localisation and intracranial analysis implicated the medial temporal lobe as the origin of this effect. Subsequent analyses disentangled head direction signatures from signals relating to head rotation and those reflecting location-specific effects. Lastly, when directly comparing head direction and eye gaze-related tuning, we found that the brain maintains both codes while actively navigating, with stronger tuning to head direction in the medial temporal lobe. Together, these results reveal a taxonomy of population-level head direction signals within the human brain that is reminiscent of those reported in the single units of rodents.

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bioRxiv2021

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.

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bioRxiv2020

Endogenous memory reactivation during sleep in humans is clocked by slow oscillation-spindle complexes.

Sleep is thought to support memory consolidation via reactivation of prior experiences, with particular electrophysiological sleep signatures (slow oscillations (SOs) and sleep spindles) gating the information flow between relevant brain areas. However, empirical evidence for a role of endogenous memory reactivation (i.e., without experimentally delivered memory cues) for consolidation in humans is lacking. Here, we devised a paradigm in which participants acquired associative memories before taking a nap. Multivariate decoding was then used to capture endogenous memory reactivation during non-rapid eye movement (NREM) sleep in surface EEG recordings. Our results reveal reactivation of learning material during SO-spindle complexes, with the precision of SO-spindle coupling predicting reactivation strength. Critically, reactivation strength (i.e. classifier evidence in favor of the previously studied stimulus category) in turn predicts the level of consolidation across participants. These results elucidate the memory function of sleep in humans and emphasize the importance of SOs and spindles in clocking endogenous consolidation processes.

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bioRxiv2017

Reactivating vocabularies in the elderly

Quality of memory and sleep decline with age, but the mechanistic interactions underlying the memory function of sleep in older adults are still unknown. It is widely assumed that the beneficial effect of sleep on memory relies on reactivation during Non-rapid eye movement (NREM) sleep, and targeting these reactivations by cue re-exposure reliably improves memory in younger participants. Here we tested whether the reactivation mechanism during sleep is still functional in old age by applying targeted memory reactivation (TMR) during NREM sleep in healthy adults over 60 years. In contrast to previous studies in young participants, older adults memories do not generally benefit from TMR during NREM sleep. On an individual level, a subgroup of older adults still profited from cueing during sleep. These improvers tended to have a better sleep efficiency than non-improvers. In addition, the oscillatory results resembled those obtained in younger participants, involving increases in theta (~6Hz) and spindle (~13 Hz) power for remembered and gained words in a later time windows. In contrast, non-improvers showed no increases in theta activity and even strongly reduced spindle power for later gained vs. lost words. Our results suggest that reactivations during sleep might lose their functionality for memory in some older adults, while this mechanism is still intact in a subgroup of participants. Further studies need to examine more closely the determinants of preserving the memory function of sleep during healthy aging.\n\nGrant informationThe study was supported by grant of the Swiss National Science Foundation (SNSF) No. 100014_162388. T.S. is supported by a grant of the Swiss National Science Foundation (SNSF) No. P2ZHP1_164994.\n\nAbbreviations

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bioRxiv2017

Theta phase coordinated memory reactivation reoccurs in a slow-oscillatory rhythm during NREM sleep

It has been proposed that sleeps contribution to memory consolidation is to reactivate prior encoded information. To elucidate the neural mechanisms carrying reactivation-related mnemonic information, we investigated whether content-specific memory signatures associated with memory reactivation during wakefulness reoccur during subsequent sleep. We show that theta oscillations orchestrate the reactivation of memories, irrespective of the physiological state. Reactivation patterns during sleep autonomously re-emerged at a rate of 1 Hz, indicating a coordination by slow oscillatory activity.

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bioRxiv2017

Cueing memory during sleep is optimal during slow-oscillatory up-states

Slow oscillations play a major role in neural plasticity. It is assumed that slow oscillatory up-states represent crucial time windows for memory reactivation and consolidation during sleep. Here we experimentally tested this assumption by utilizing closed-loop targeted memory reactivation (closed-loop TMR): Healthy participants were re-exposed to prior learned foreign vocabulary during up- and down-states of slow oscillations, respectively, in a within-subject design. We show that presenting memory cues during slow oscillatory up-states robustly improves recall performance, whereas memory cueing during down-states did not result in a clear behavioral benefit. On a neural basis successful memory reactivation during up-states was associated with a characteristic power increase in the theta and sleep spindle band. Such increases were completely absent for down-state memory cues. Our findings provide experimental support for the assumption that slow oscillatory up-states represent privileged time windows for memory reactivation, while the interplay of slow oscillations, theta and sleep spindle activity promote successful memory consolidation during sleep.

neuroscience↗