Understanding the intricate mechanisms underlying slow-wave sleep (SWS) is crucial for deciphering the brain's role in memory consolidation and cognitive functions. It is well established that cortical delta oscillations (0.5-4 Hz) coordinate communications among cortical, hippocampal, and thalamic regions during SWS. These delta oscillations feature periods of Up and Down states, with the latter previously thought to represent complete cortical silence; however, new evidence suggests that Down states serve important functions for information exchange during memory consolidation. The retrosplenial cortex (RSC) is pivotal for memory consolidation due to its extensive connectivity with memory-associated regions, although it remains unclear how RSC neurons engage in delta-associated consolidation processes. Here, we employed multichannel in vivo electrophysiology to study RSC neuronal activity in ad libitum behaving male mice during natural SWS. We discovered a discrete assembly of putative excitatory RSC neurons (∼20%) that initiated firing at SWS Down states and reached maximal firing at the Down-to-Up transitions. Therefore, we termed these RSC neurons the Down-to-Up transition assembly (DUA) and the remaining RSC excitatory neurons as non-DUA. Compared with non-DUA, DUA neurons appear to exhibit higher firing rates and larger cell body size and lack monosynaptic connectivity with nearby RSC neurons. Furthermore, optogenetics combined with electrophysiology revealed differential innervation of RSC excitatory neurons by memory-associated inputs. Collectively, these findings provide insight into the distinct activity patterns of RSC neuronal subpopulations during sleep and their potential role in memory processes.

Sleep supports memory consolidation, but the specific roles of different sleep stages in this process remain unclear. While rapid eye movement sleep (REM) has traditionally been linked to the processing of emotionally charged material, recent evidence suggests that slow wave sleep (SWS) also plays a role in strengthening emotional memories. Here, we use targeted memory reactivation (TMR) during REM and SWS in a daytime nap to directly examine which sleep stage is primarily involved in consolidating emotional declarative memories. Contrary to our hypothesis, reactivating emotional stimuli during REM impairs memory. Meanwhile, TMR benefit in SWS is strongly correlated with the product of time spent in REM and SWS. The emotional valence of cued items modulates both delta/theta power and sleep spindles. Furthermore, emotional memories benefit more from TMR than neutral ones. Our findings suggest that SWS and REM have complementary roles in consolidating emotional memories, with REM potentially involved in forgetting them. These results also expand on recent evidence highlighting a connection between sleep spindles and emotional processing.

Retrieval practice enhances memory for practiced information, but at the price of impairing memory for unpracticed information, a phenomenon known as retrieval-induced forgetting (RIF). Evidence has shown that, for young adults, RIF can be eliminated after a long interval and when textual information is used as a memorandum. The current study aims to determine whether RIF is more durable and difficult to overcome for older adults due to their cognitive deficits. Both young and older participants completed a learning session on Day 1, during which they studied word pairs (Experiment 1) or scientific prose (Experiment 2). Then, they engaged in selective retrieval practice on Days 3, 5, or 7. Finally, they undertook a final test on Day 8. Experiment 1 showed no RIF for young but a robust RIF for older participants. Experiment 2 observed retrieval-induced facilitation for young but RIF for older participants. Although both young and older participants were encouraged to use an integration technique to facilitate learning during Experiment 2, the levels of integration only predicted the magnitudes of retrieval-induced facilitation for young but not for older participants. This study shows that older adults should be careful of carrying out selective retrieval because this may produce a more durable impairment in their memory for unpracticed information.

Sleep is critically involved in strengthening memories. However, our understanding of the morphological changes underlying this process is still emerging. Recent studies suggest that specific subsets of dendritic spines are strengthened during sleep in specific neurons involved in recent learning. Contextual memories associated with traumatic experiences are involved in post-traumatic stress disorder (PTSD) and represent recent learning that may be strengthened during sleep. We tested the hypothesis that dendritic spines encoding contextual fear memories are selectively strengthened during sleep. Furthermore, we tested how sleep deprivation after initial fear learning impacts dendritic spines following re-exposure to fear conditioning. We used ArcCreERT2 mice to visualize neurons that encode contextual fear learning (Arc+ neurons), and concomitantly labeled neurons that did not encode contextual fear learning (Arc- neurons). Dendritic branches of Arc+ and Arc- neurons were sampled using confocal imaging to assess spine densities using three-dimensional image analysis from either sleep deprived (SD) or control mice allowed to sleep normally. Mushroom spines in Arc+ branches displayed decreased density in SD mice, indicating upscaling of mushroom spines during sleep following fear learning. In comparison, no changes were observed in dendritic spines from Arc- branches. When animals were re-exposed to contextual fear conditioning 4 weeks later, we observed lower density of mushroom spines in both Arc+ and Arc- branches, as well as lower density of thin spines in Arc- branches in mice that were SD following the initial fear conditioning trial. Our findings indicate that sleep strengthens dendritic spines in neurons that recently encoded fear memory, and sleep deprivation following initial fear learning impairs dendritic spine strengthening initially and following later re-exposure. SD following a traumatic experience thus may be a viable strategy in weakening the strength of contextual memories associated with trauma and PTSD.

We review recent progress in understanding fundamental aspects of physiologic regulation during wake and sleep based on modern data-driven, analytical, and computational approaches with a focus on the complex dynamics of individual physiologic systems. The presented empirical findings indicate that sleep-wake and circadian cycles do not simply modulate basic physiologic functions but influence physiologic systems dynamics simultaneously over a broad range of time scales. The reviewed empirical approaches and derived measures represent novel mechanistic aspects of sleep and wake regulation, and lay the foundation for a new class of diagnostic and prognostic biomarkers in clinical sleep medicine.

This study examined the effect of a 40-min nap (N40) the day after a night session of the Loughborough Intermittent Shuttle Test (LIST), before, during and after Ramadan. In a randomized crossover design, fifteen male soccer players completed the LIST in the evening (2100h), followed by either a N40 or no nap (N0) the next day, at 1400h. Performance on the 5-m shuttle run test (5mSRT), digit cancellation test (DCT), and subjective measures (i.e., sleepiness, rating of perceived exertion, and muscle soreness) were assessed at 1700h. During Ramadan, 5mSRT and DCT performance decreased compared to before Ramadan in the N0 condition (p<0.05). However, N40 improved 5mSRT and DCT performance across all periods compared to N0 (p<0.05). In conclusion, a 40-min of nap opportunity is an effective strategy for improving physical and cognitive performance during and following Ramadan after a bout of exercise the previous night.    .

Long term cognitive impairment affects about half of cardiac arrest survivors, typically attributed to postanoxic encephalopathy. Sleep disorders are common after acute brain injuries and may also impair cognition. We investigated the prevalence of sleep disorders in cardiac arrest survivors and their relation with cognitive function.

Thirty survivors completed neuropsychological examination and questionnaires on mood (Hospital anxiety and depression scale), daytime sleepiness (Epworth sleepiness scale), and sleep quality (Pittsburgh sleep quality index), and underwent polysomnography one year after cardiac arrest. Questionnaire outcomes and objective sleep parameters (sleep-apnea, leg movements, cyclicity) were correlated with performance on neuropsychological tests using Pearson R, Kruskal-Wallis, or Mann-Whitney U tests.

Thirty-six percent of participants had moderate to severe obstructive sleep apnea, and 43% moderate to severe periodic limb movements during sleep according to polysomnography. Obstructive sleep apnea was correlated with poorer executive functioning (R = -0.38; p < 0.05) and memory (R = -0.50; p < 0.05). Fewer sleep cycles were correlated with poorer attention (R = 0.36, p = 0.05). Questionnaire outcomes (mood, daytime sleepiness, sleep quality) were not related to cognition. Participants with moderate/severe obstructive sleep apnea had worse executive functioning than those with no/mild obstructive sleep apnea (p = 0.02).

This explorative study shows moderate to severe sleep disorders are common in cardiac arrest survivors and that moderate to severe obstructive sleep apnea relates to poorer cognitive function. This implies that diagnosis and treatment of obstructive sleep apnea may offer a treatment target for cardiac arrest survivors with cognitive impairment.

Sleep loss increases AMPA-synaptic strength and number in the neocortex. However, this is only part of the synaptic sleep loss response. We report an increased AMPA/NMDA EPSC ratio in frontal-cortical pyramidal neurons of layers 2-3. Silent synapses are absent, decreasing the plastic potential to convert silent NMDA to active AMPA synapses. These sleep loss changes are recovered by sleep. Sleep genes are enriched for synaptic shaping cellular components controlling glutamate synapse phenotype, overlap with autism risk genes, and are primarily observed in excitatory pyramidal neurons projecting intra-telencephalically. These genes are enriched with genes controlled by the transcription factor, MEF2c, and its repressor, HDAC4. Sleep genes can thus provide a framework within which motor learning and training occur mediated by the sleep-dependent oscillation of glutamate-synaptic phenotypes.

Disrupted nighttime sleep is common in pediatric narcolepsy type 1, yet its cognitive impact is unknown. As N2 sleep spindles are necessary for sleep-dependent memory consolidation, we hypothesized that narcolepsy type 1 impairs memory consolidation via N2 sleep fragmentation and N2 sleep spindle alterations.

We trained 28 pediatric narcolepsy type 1 participants and 27 healthy controls (HCs) on a spatial declarative memory task before a nocturnal in-lab polysomnogram and then gave them a cued recall test upon awakening in the morning. We extracted wake and sleep stage bout numbers and N2 spindle characteristics from the polysomnogram and conducted mixed model analysis of sleep-dependent memory consolidation to identify group differences.

Narcolepsy type 1 participants had shorter N2 bout durations and associated shorter N2 spindles versus HC, but other N2 spindle features were similar. Narcolepsy type 1 participants had worse memory performance postsleep than HCs after adjusting for age and gender (mean memory consolidation HC: -3.1% ± 18.7, NT1: -15.6 ± 24.8, main effect group × time of testing F = 5.3, p = .03). We did not find significant relationships between sleep-dependent memory consolidation and N2 spindle characteristics. Notably, increased N1% was associated with worse sleep-dependent memory consolidation with results driven by the narcolepsy type 1 group.

Sleep-dependent memory consolidation is mildly impaired in youth with narcolepsy type 1 and findings may be attributed to increases in N1 sleep. Further studies are needed to determine if these findings are generalizable and reversible with sleep-based therapies.

For retention intervals of up to 12 h, the active systems consolidation hypothesis predicts that sleep compared to wakefulness strengthens the context binding of memories previously established during encoding. Sleep should thus improve source memory. By comparing retention intervals filled with natural night sleep versus daytime wakefulness, we tested this prediction in two online source-monitoring experiments using intentionally learned pictures as items and incidentally learned screen positions and frame colors as source dimensions. In Experiment 1, we examined source memory by varying the spatial position of pictures on the computer screen. Multinomial modeling analyses revealed a significant sleep benefit in source memory. In Experiment 2, we manipulated both the spatial position and the frame color of pictures orthogonally to investigate source memory for two different source dimensions at the same time, also allowing exploration of bound memory for both source dimensions. The sleep benefit on spatial source memory replicated. In contrast, no source memory sleep benefit was observed for either frame color or bound memory of both source dimensions, probably as a consequence of a floor effect in incidental encoding of color associations. In sum, the results of both experiments show that sleep within a 12-h retention interval improves source memory for spatial positions, supporting the prediction of the active systems consolidation hypothesis. However, additional research is required to clarify the impact of sleep on source memory for other context features and bound memories of multiple source dimensions.

The positive effects of physical activity (PA) on sleep are widely promoted by public health organizations and supported by abundant empirical evidence. Nonetheless, there remains a dearth of studies investigating the association between daytime PA and nighttime sleep among non-urban and nonindustrial populations that habitually engage in PA as part of their subsistence strategy.

Here, we examined the bidirectional relationship between PA and sleep. We also looked at age, gender, and occupation-level differences in moderate-to-vigorous-intensity PA (MVPA), low-intensity PA (LPA), and sedentary activity durations among Basotho and Xhoxa agropastoralists residing in rural villages in the Eastern Cape, South Africa. We analyzed activity and sleep data collected from 113 individuals using MotionWatch actigraphy wristwatches across three field seasons (7111 individual days).

Percentage daily total MVPA decreased with age, though older participants maintained low activity levels and did not suffer from poorer sleep compared to younger participants. Herders spent more percentage of their day in higher-intensity activity than non-herders. Overall, women had greater daily percentage MVPA and lower percentage sedentary activity than men. Durations of total MVPA and LPA decreased total sleep time (TST) and improved sleep quality (increased sleep efficiency (SE), decreased fragmentation, and decreased percentage wake after sleep onset). Daytime PA measures were not affected by sleep duration or quality from the previous night.

Among this group of habitually active agropastoralists, low-to-moderate-intensity PA durations consistently predicted higher sleep quality. Our findings showed that sleep quality was more strongly affected by PA than sleep duration.

Sleep posture is a key factor in assessing sleep quality, especially for individuals with Obstructive Sleep Apnea (OSA), where the sleeping position directly affects breathing patterns: the side position alleviates symptoms, while the supine position exacerbates them. Accurate detection of sleep posture is essential in assessing and improving sleep quality. Automatic sleep posture detection systems, both wearable and non-wearable, have been developed to assess sleep quality. However, wearable solutions can be intrusive and affect sleep, while non-wearable systems, such as camera-based approaches and pressure sensor arrays, often face challenges related to privacy, cost, and computational complexity. The system in this paper proposes a microcontroller-based approach exploiting the execution of an embedded machine learning (ML) model for posture classification. By locally processing data from a minimal set of pressure sensors, the system avoids the need to transmit raw data to remote units, making it lightweight and suitable for real-time applications. Our results demonstrate that this approach maintains high classification accuracy (i.e., 0.90 and 0.96 for the configurations with 6 and 15 sensors, respectively) while reducing both hardware and computational requirements.

Evidence has established the prominent involvement of rapid eye movement (REM) sleep disturbance in major depressive disorder (MDD). However, the neural correlates of REM sleep in MDD and their clinical significance are less clear.

Cross-sectional and longitudinal polysomnography and resting-state functional MRI data were collected from 131 MDD patients and 71 healthy controls to measure REM sleep and voxel-mirrored homotopic connectivity (VMHC). Correlation and mediation analyses were performed to examine the associations between REM sleep, VMHC, and clinical variables. Moreover, we conducted spatial correlations between the neural correlates of REM sleep and a multimodal collection of reference brain maps to facilitate genetic, structural and functional annotations.

MDD patients exhibited REM sleep abnormalities manifesting as higher REM sleep latency and lower REM sleep duration, which were correlated with decreased VMHC of the precentral gyrus and inferior parietal lobe and mediated their associations with more severe anxiety symptoms. Longitudinal data showed that VMHC increase of the inferior parietal lobe was related to improvement of depression symptoms in MDD patients. Spatial correlation analyses revealed that the neural correlates of REM sleep in MDD were linked to gene categories primarily involving cellular metabolic process, signal pathway, and ion channel activity as well as linked to cortical microstructure, metabolism, electrophysiology, and cannabinoid receptor.

These findings may add important context to the growing literature on the complex interplay between sleep and MDD, and more broadly may inform future treatment for depression via regulating sleep.

Compared to the general population, military personnel are at increased risk for insomnia and poor psychological well-being. The present study: (1) compared categories of insomnia severity between cadets of the Swiss Armed Forces (SAF) and previously published norms and (2) investigated the associations between insomnia and psychological well-being related to perceived stress, mental toughness, dark triad traits, and organizational citizenship behavior (OCB).

A total of 216 cadets of the SAF (mean age: 20.80 years) completed self-rating questionnaires covering sociodemographic information, insomnia, perceived stress, mental toughness, dark triad, and organizational citizenship behavior. Data on insomnia sum scores and categories of historical samples (862 young adults and 533 police and emergency response service officers) were used for comparison.

Cadets of the SAF reported higher insomnia sum scores and insomnia severity categories, compared to young adults and police officers. Higher scores for insomnia were associated with higher scores for stress, dark triad traits, and with lower scores for mental toughness and OCB. Categories of low, medium, and high stress moderated the association between insomnia and dark triad traits.

Compared to norms of the general population, cadets of the SAF reported a higher insomnia severity. Given that standardized treatment programs for insomnia, mental toughness, and above all for coping with stress are available, such interventions might be promising avenues to improve a cadet's overall sleep, psychological well-being, and behavior.

It is presumed by many that acute sleep loss results in degraded in-game esports (competitive, organized video game play) performance. However, this has not been experimentally investigated to date. The objective of the current experiment was to elucidate whether ~29hrs of total sleep deprivation impacts in-game performance for the popular esport Rocket League.

Twenty skill-matched pairs (N = 40 total) were recruited. Within each pair, one participant was assigned to an intervention group (TSD), while the other was assigned to a control group (CON). Two test sessions occurred; one while both participants were rested (baseline), and the other while the CON participant was rested but the TSD participant was sleep deprived (experimental).

Following total sleep deprivation, TSD participants reported higher Karolinska Sleepiness Scale-measured subjective sleepiness and lower subjective alertness and motivation, as well as worsened PVT response speed and ~5 times greater PVT lapse incidence, and worsened response speed on a two-choice categorization task. However, overall in-game Rocket League performance did not worsen due to total sleep deprivation. Exploratory analyses of performance indicators suggest a potential shift toward a simpler and safer strategy following sleep deprivation.

Following a bout of ~29hrs total sleep deprivation, overall in-game Rocket League performance remained unaffected. This presents as a promising finding given the high potential for acute pre-competition sleep disturbance in esports, though habitual sleep remains a concern for esport athletes.

Arousal states are thought to influence many aspects of cognition and behavior by broadly modulating neural activity. Many studies have observed arousal-related modulations of alpha (~8 to 15 Hz) and gamma (~30 to 50 Hz) power and coherence in local field potentials across relatively small groups of brain regions. However, the global pattern of arousal-related oscillatory modulation in local field potentials is yet to be fully elucidated. We simultaneously recorded local field potentials in numerous cortical and subcortical regions in the primate brain and assessed oscillatory activity and inter-regional coherence associated with arousal state. In high arousal states, we found a uniquely strong and coherent gamma oscillation between the amygdala and basal forebrain. In low arousal rest-like states, a relative increase in coherence at alpha frequencies was present across sampled brain regions, with the notable exception of the medial temporal lobe. We consider how these patterns of activity may index arousal-related brain states that support the processing of incoming sensory stimuli during high arousal states and memory-related functions during rest.

The association between sleep quality and cognition is widely established, but the role of aging in this relationship is largely unknown.

To examine how age impacts the sleep-cognition relationship and determine whether there are sensitive ranges when the relationship between sleep and cognition is modified. This investigation could help identify individuals at risk for sleep-related cognitive impairment.

Sample included 711 individuals (ages 36.00-89.83, 59.66 ± 14.91, 55.7 % female) from the Human Connectome Project-Aging (HCP-A).

The association between sleep quality (Pittsburgh Sleep Quality Index, PSQI) and cognition (Crystallized Cognition Composite and Fluid Cognition Composite from the NIH Toolbox, the Trail Making Test, TMT, and the Rey Auditory Verbal Learning Test, RAVLT) was measured using linear regression models, with sex, race, use of sleep medication, hypertension, and years of education as covariates. The interaction between sleep and age on cognition was tested using the moderation analysis, with age as both continuous linear and nonlinear (quadratic) terms.

There was a significant interaction term between the PSQI and nonlinear age term (age2) on TMT-B (p = 0.02) and NIH Toolbox crystallized cognition (p = 0.02), indicating that poor sleep quality was associated with worse performance on these measures (sensitive age ranges 50-75 years for TMT-B and 66-70 years for crystallized cognition).

The sleep-cognition relationship may be modified by age. Individuals in the middle age to early older adulthood age band may be most vulnerable to sleep-related cognitive impairment.

Sleep loss increases AMPA-synaptic strength and number in the neocortex. However, this is only part of the synaptic sleep loss response. We report increased AMPA/NMDA EPSC ratio in frontal-cortical pyramidal neurons of layers 2-3. Silent synapses are absent, decreasing the plastic potential to convert silent NMDA to active AMPA synapses. These sleep loss changes are recovered by sleep. Sleep genes are enriched for synaptic shaping cellular components controlling glutamate synapse phenotype, overlap with autism risk genes and are primarily observed in excitatory pyramidal neurons projecting intra-telencephalically. These genes are enriched with genes controlled by the transcription factor, MEF2c and its repressor, HDAC4. Sleep genes can thus provide a framework within which motor learning and training occurs mediated by sleep-dependent oscillation of glutamate-synaptic phenotypes.

Over time, memories lose episodic detail and become distorted, a process with serious ramifications for eyewitness identification. What are the processes contributing to such transformations over time? We investigated the roles of post-learning sleep and retrieval practice in memory accuracy and distortion, using a naturalistic story recollection task. Undergraduate students listened to a recording of the "War of the Ghosts," a Native American folktale, and were assigned to either a sleep or wake delay group, and either a retrieval practice or listen-only study condition. We found higher accuracy after sleep compared to wake in the listen-only condition, but not in the retrieval practice condition. This effect was driven by participants in the wake, retrieval practice condition showing superior memory compared to the wake, listen-only condition. A similar pattern was found for memory distortion, with both sleep and retrieval practice being associated with more inferences of nonpresented, but story-related information, compared to the wake, listen-only condition. These findings suggest both sleep and retrieval practice contribute to narrative memory stabilization and distortion.

Sleep is an essential component of productive memory consolidation and waste clearance, including pathology associated with Alzheimer's disease (AD). Facilitation of sleep decreases Aβ and tau accumulation and is important for the consolidation of spatial memories. We previously found that 6-month female 3xTg-AD mice were impaired at spatial reorientation. Given the association between sleep and AD, we assessed the impact of added rest on impaired spatial reorientation that we previously observed. We randomly assigned 3xTg-AD mice to a rest (n=7; 50 min pre- & post-task induced rest) or a non-rest group (n=7; mice remained in the home cage pre- & post-task). Mice in both groups were compared to non-Tg, age-matched, non-rest controls (n=6). To confirm that our sleep condition induced sleep, we performed the same experiment with rest sessions for both 3xTg-AD and non-Tg mice (n=6/group) implanted with recording electrodes to capture local field potentials (LFPs), which were used to classify sleep states. Markers of pathology were also assessed in the parietal-hippocampal network, where we previously showed pTau positive cell density predicted spatial reorientation ability (pTau, 6E10, M78, and M22). However, we found that 3xTg-AD rest mice were not impaired at spatial reorientation compared to non-Tg mice and performed better than 3xTg-AD non-rest mice (replicating our previous work). This recovered behavior persisted despite no change in the density of pathology positive cells. Thus, improving sleep in early stages of AD pathology offers a promising approach for facilitating memory consolidation and improving cognition.

Both rapid eye movement and non-rapid eye movement sleep are important for cognitive function and well-being, yet few studies have examined whether human sleep architecture is affected by long-duration spaceflight. We recorded 256 nights of sleep from five crew members before (n = 112 nights), during (n = 83 nights) and after (n = 61 nights) ~6-month missions aboard the Mir space station, using the Nightcap sleep monitor. We compared sleep outcomes (including total sleep time, efficiency, latency, rapid eye movement and non-rapid eye movement) during spaceflight with those on Earth. We also evaluated longitudinal changes over time in space. We found that wakefulness increased by 1 hr in space compared with on Earth. Over time in space, rapid eye movement was initially reduced and then recovered to near preflight levels at the expense of non-rapid eye movement sleep. Upon return to Earth, sleep architecture returned to preflight distribution. Our findings suggest that spaceflight may alter sleep architecture and should be explored further.

This study aimed to (1) improve sleep staging accuracy through transfer learning (TL), to achieve or exceed human inter-expert agreement and (2) introduce a scorability model to assess the quality and trustworthiness of automated sleep staging.

A deep neural network (base model) was trained on a large multi-site polysomnography (PSG) dataset from the United States. TL was used to calibrate the model to a reduced montage and limited samples from the Korean Genome and Epidemiology Study (KoGES) dataset. Model performance was compared to inter-expert reliability among three human experts. A scorability assessment was developed to predict the agreement between the model and human experts.

Initial sleep staging by the base model showed lower agreement with experts (κ = 0.55) compared to the inter-expert agreement (κ = 0.62). Calibration with 324 randomly sampled training cases matched expert agreement levels. Further targeted sampling improved performance, with models exceeding inter-expert agreement (κ = 0.70). The scorability assessment, combining biosignal quality and model confidence features, predicted model-expert agreement moderately well (R² = 0.42). Recordings with higher scorability scores demonstrated greater model-expert agreement than inter-expert agreement. Even with lower scorability scores, model performance was comparable to inter-expert agreement.

Fine-tuning a pretrained neural network through targeted TL significantly enhances sleep staging performance for an atypical montage, achieving and surpassing human expert agreement levels. The introduction of a scorability assessment provides a robust measure of reliability, ensuring quality control and enhancing the practical application of the system before deployment. This approach marks an important advancement in automated sleep analysis, demonstrating the potential for AI to exceed human performance in clinical settings.

To examine sleep disruption in chronic traumatic brain injury (TBI) across 3 aims: (1) to examine differences in self-reported sleep disruption between adults with and without a chronic history of TBI; (2) to query reported changes in sleep after TBI; and (3) to explore the relationship between self-reported sleep disruption and memory failures in daily life.

Community-dwelling participants completed self-report sleep and memory surveys as part of their participation in a larger patient registry.

This study included 258 participants, and half (n = 129) of them have a chronic history of moderate-severe TBI (mean time since injury is 5.1 [SD 6.5] years).

We report descriptive statistics from this matched cross-sectional study on sleep in the chronic phase of injury. We also used planned Wilcoxon ranked-sum tests and exploratory correlations to examine the relationships of sleep disruption with TBI diagnosis, injury chronicity, and memory.

We used the Pittsburgh Sleep Quality Index to measure sleep disruption and the Epworth Sleepiness Scale to measure daytime sleepiness. Participants answered questions about postinjury sleep and responded to the Everyday Memory Questionnaire as a measure of memory failures in daily life.

Individuals with TBI had significantly higher rates of sleep disruption than those without TBI, as measured by the Pittsburgh Sleep Quality Index but not on the Epworth Sleepiness Scale. Sleep disruption in TBI manifested more in sleep quality than quantity. Half of the participants with TBI reported a negative change in sleep postinjury. In an exploratory analysis, sleep disruption was related to memory failure in daily life in the TBI sample.

Sleep disruption persists long after TBI but may be under-recognized in people with chronic TBI. Given that sleep is critical for memory and rehabilitation outcomes well into the chronic phase of injury, steps to improve the identification and management of sleep disruption are needed. Key words:chronic, memory, sleep, traumatic brain injury.

Sleep is known to drive the consolidation of motor memories. During nonrapid eye movement (NREM) sleep, the close temporal proximity between slow oscillations (SOs) and spindles ("nesting" of SO-spindles) is known to be essential for consolidation, likely because it is closely associated with the reactivation of awake task activity. Interestingly, recent work has found that spindles can occur in temporal clusters or "trains." However, it remains unclear how spindle trains are related to the nesting phenomenon. Here, we hypothesized that spindle trains are more likely when SOs co-occur in the prefrontal and motor cortex. We conducted simultaneous neural recordings in the medial prefrontal cortex (mPFC) and primary motor cortex (M1) of male rats training on the reach-to-grasp motor task. We found that intracortically recorded M1 spindles are organized into distinct temporal clusters. Notably, the occurrence of temporally precise SOs between mPFC and M1 was a strong predictor of spindle trains. Moreover, reactivation of awake task patterns is much more persistent during spindle trains in comparison with that during isolated spindles. Together, our work suggests that the precise coupling of SOs across mPFC and M1 may be a potential driver of spindle trains and persistent reactivation of motor memory during NREM sleep.

Learning new motor skills through training, also termed motor learning, is central for everyday life. Current training strategies recommend intensive task-repetitions aimed at inducing local activation of motor areas, associated with changes in oscillation amplitudes ("event-related power") during training. More recently, another neural mechanism was suggested to influence motor learning: modulation of functional connectivity (FC), that is, how much spatially separated brain regions communicate with each other before and during training. The goal of the present study was to compare the impact of these two neural processing types on motor learning. We measured EEG before, during, and after a finger-tapping task (FTT) in 20 healthy subjects. The results showed that training gain, long-term expertise (i.e., average motor performance), and consolidation were all predicted by whole-brain alpha- and beta-band FC at motor areas, striatum, and mediotemporal lobe (MTL). Local power changes during training did not predict any dependent variable. Thus, network dynamics seem more crucial than local activity for motor sequence learning, and training techniques should attempt to facilitate network interactions rather than local cortical activation.

Insomnia is an emerging risk factor for the onset of mild cognitive impairment (MCI) and its progression to dementia. Impaired cognition and neuropsychiatric symptoms create challenges for persons with MCI to participate actively in non-pharmacological interventions. This study examined the feasibility and preliminary effects of empowerment-based cognitive-behavioural therapy for insomnia (CBT-I) on sleep, cognitive function, and health-related quality of life (HRQoL) in persons with MCI and sleep problems. Sixty participants were randomly allocated to the intervention or control group to receive empowerment-based CBT-I or usual care, respectively. The 12 week intervention comprised all core CBT-I techniques delivered through a group and individualised face-to-face approach. An empowerment approach with interactive teaching methods, goal setting, and action planning was used to deliver the intervention. Outcome measures included subjective and objective sleep quality and pattern, and a battery of neuropsychological tests and the 12-item Short Form Survey were administered 3 months (T1) and 6 months post-randomisation (T2). This intervention is feasible and highly acceptable for persons with MCI. The intervention group showed significant improvements in subjective and objective sleep-related outcomes compared with the control group. Moreover, the intervention group showed greater improvements in global cognition, processing speed, attention, and mental flexibility than the control group at T1 and/or T2. No significant between-group differences were observed in memory or HRQoL scores. The qualitative data converged with the quantitative data. In conclusion, empowerment-based CBT-I was well received by persons with MCI and had potential positive effects on improving sleep and cognition in this cohort.

Many experiences unfold predictably over time. Memory for these temporal regularities enables anticipation of events multiple steps into the future. Because temporally predictable events repeat over days, weeks, and years, we must maintain-and potentially transform-memories of temporal structure to support adaptive behavior. We explored how individuals build durable models of temporal regularities to guide multistep anticipation. Healthy young adults (Experiment 1: N = 99, age range = 18-40 years; Experiment 2: N = 204, age range = 19-40 years) learned sequences of scene images that were predictable at the category level and contained incidental perceptual details. Individuals then anticipated upcoming scene categories multiple steps into the future, immediately and at a delay. Consolidation increased the efficiency of anticipation, particularly for events further in the future, but diminished access to perceptual features. Further, maintaining a link-based model of the sequence after consolidation improved anticipation accuracy. Consolidation may therefore promote efficient and durable models of temporal structure, thus facilitating anticipation of future events.

An acute bout of exercise in the moments after learning benefits the retention of new memories. This finding can be explained, at least partly, through a consolidation account: exercise provides a physiological state that is conducive to the early stabilisation of labile new memories, which supports their retention and subsequent retrieval. The modification of consolidation through non-invasive exercise interventions offers great applied potential. However, it remains poorly understood whether effects of exercise translate from the laboratory to naturalistic settings and whether the intensity of exercise determines the effect in memory. To this end, adult endurance runners were recruited as participants and completed two study sessions spaced two weeks apart. In each session, participants were presented with a list of words and asked to recall them on three occasions: (i) immediately following their presentation, (ii) after a 30-minute retention interval, and (iii) after 24 hours. Crucially, the 30-minute retention interval comprised our experimental manipulation: higher intensity exercise (running) in the first session and lower intensity exercise (walking) in the second, both completed in a naturalistic setting around participants' existing physical activity training programmes. Exertion was recorded through heart rate and rate of perceived exertion data. Alertness, mood, and arousal ratings were also collected before and after the 30-minute retention interval. Immediate memory for the two wordlists was matched, but participants retained significantly more words after 30 minutes and 24 hours when encoding was followed by higher than lower intensity exercise. Exertion data revealed that participants experienced vigorous and light exercise in the higher and lower intensity conditions, respectively. Significant improvements in alertness, mood, and arousal were observed following both exercise conditions, but especially in the higher intensity condition. These outcomes reveal that experiencing higher intensity physical activity in the field is conducive to declarative memory retention, possibly because it encourages consolidation.

Despite advances in understanding the cellular and molecular processes underlying memory and cognition, and recent successful modulation of cognitive performance in brain disorders, the neurophysiological mechanisms remain underexplored. High frequency oscillations beyond the classic electroencephalogram spectrum have emerged as a potential neural correlate of fundamental cognitive processes. High frequency oscillations are detected in the human mesial temporal lobe and neocortical intracranial recordings spanning gamma/epsilon (60-150 Hz), ripple (80-250 Hz) and higher frequency ranges. Separate from other non-oscillatory activities, these brief electrophysiological oscillations of distinct duration, frequency and amplitude are thought to be generated by coordinated spiking of neuronal ensembles within volumes as small as a single cortical column. Although the exact origins, mechanisms and physiological roles in health and disease remain elusive, they have been associated with human memory consolidation and cognitive processing. Recent studies suggest their involvement in encoding and recall of episodic memory with a possible role in the formation and reactivation of memory traces. High frequency oscillations are detected during encoding, throughout maintenance, and right before recall of remembered items, meeting a basic definition for an engram activity. The temporal coordination of high frequency oscillations reactivated across cortical and subcortical neural networks is ideally suited for integrating multimodal memory representations, which can be replayed and consolidated during states of wakefulness and sleep. High frequency oscillations have been shown to reflect coordinated bursts of neuronal assembly firing and offer a promising substrate for tracking and modulation of the hypothetical electrophysiological engram.

Sleep is essential in the process of memory consolidation. Children and adolescents with epilepsy hold a significantly higher risk for memory impairment. Understanding the relationship between sleep and memory impairment in adolescents with epilepsy will help us to develop effective support services for this patient population. The present study provides a summary of the current research on the influence of epilepsy-related altered sleep patterns on memory consolidation in children and adolescents with epilepsy. The aim of this systematic review is to investigate the influence of epilepsy-related altered sleep conditions in children and adolescents and their impact on memory performance.

A systematic review was conducted according to the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses using the search terms "memory," "sleep," "epilepsy," "children," and "adolescents." A total of 4 studies met the inclusion criteria. The review focused on the association of sleep disorders and memory performance in children and adolescents aged up to 21 years without psychiatric comorbidities.

The reviewed studies highlight a higher risk of sleep disturbance and lower sleep quality in children with epilepsy in comparison to control groups. Group differences in memory consolidation were found before, but not after one night of sleep. Three studies reported a significant association between sleep and memory performance. Two studies demonstrated an association between nocturnal interictal epileptiform discharges and memory performance in adolescents.

Children and adolescents with epilepsy have a higher risk of sleep and memory disorders. Nocturnal interictal epileptiform discharges have been shown to interfere with memory consolidation. Conclusions on underlying mechanisms remain unclear. Further case-control studies addressing sleep and its influence on memory problems in pediatric epilepsy patients are needed.

Sleep is considered closely related to cognitive function, and cognitive impairment is the main clinical manifestation of Alzheimer's disease (AD). Sleep disturbance in AD patients is more severe than that in healthy elderly individuals. Additionally, sleep deprivation reportedly increases the activity of the hypothalamic orexin system and the risk of AD. To investigate whether intervention with the orexin system can improve sleep disturbance in AD and its impact on AD pathology. In this study, six-month-old amyloid precursor protein/presenilin 1 mice were subjected to six weeks of chronic sleep deprivation and injected intraperitoneally with almorexant, a dual orexin receptor antagonist (DORA), to investigate the effects and mechanisms of sleep deprivation and almorexant intervention on learning and memory in mice with AD. We found that sleep deprivation aggravated learning and memory impairment and increased brain β-amyloid (Aβ) deposition in mice with AD. The application of almorexant can increase the total sleep time of sleep-deprived mice and reduce cognitive impairment and Aβ deposition, which is related to the improvement in Aquaporin-4 polarity. Thus, DORA may be an effective strategy for delaying the progression of AD patients by improving the sleep disturbances.

Sleep is considered to promote gist abstraction on the basis of spontaneous memory reactivation. As speculated in the theory of 'information overlap to abstract (iOtA)', 'overlap' between reactivated memories, beyond reactivation, is crucial to gist abstraction. Yet so far, empirical research has not tested this theory by manipulating the factor of 'overlap'. In the current study, 'overlap' itself was manipulated by targeted memory reactivation (TMR), through simultaneously reactivating multiple memories that either contain or do not contain spatially overlapped gist information, to investigate the effect of overlapping reactivation on gist abstraction. This study had a factorial design of 2 factors with 2 levels respectively (spatial overlap/no spatial overlap, TMR/no-TMR). Accordingly, 82 healthy college students (aged 19 ∼ 25, 57 females) were randomized into four groups. After learning 16 pictures, paired with 4 auditory cues (4 pictures - 1 cue) according to the grouping, participants were given a 90-minute nap opportunity. Then TMR cueing was conducted during N2 and slow wave sleep of the nap. Performance in memory task was used to measure gist abstraction. The results showed a significant main effect of TMR on both implicit and explicit gist abstraction, and a marginally significant interaction effect on explicit gist abstraction. Further analyses showed that explicit gist abstraction in the spatial overlap & TMR group was significantly better than in the control group. Moreover, explicit gist abstraction was positively correlated with spindle density. The current study thus indicates that TMR facilitates gist abstraction, and explicit gist abstraction may benefit more from overlapping reactivation.

Sleep staging plays an important role in the diagnosis and treatment of clinical sleep disorders. The sleep staging standard defines every 30 seconds as a sleep period, which may mean that there exist similar brain activity patterns during the same sleep period. Thus, in this work, we propose a novel time-related synchronization analysis framework named time-related multimodal sleep scoring model (TRMSC) to explore the potential time-related patterns of sleeping. In the proposed TRMSC, the time-related synchronization analysis is first conducted on the single channel electrophysiological signal, i.e., Electroencephalogram (EEG) and Electrooculogram (EOG), to explore the time-related patterns, and the spectral activation features are also extracted by spectrum analysis to obtain the multimodal features. With the extracted multimodal features, the feature fusion and selection strategy is utilized to obtain the optimal feature set and achieve robust sleep staging. To verify the effectiveness of the proposed TRMSC, sleep staging experiments were conducted on the Sleep-EDF dataset, and the experimental results indicate that the proposed TRMSC has achieved better performance than other existing strategies, which proves that the time-related synchronization features can make up for the shortcomings of traditional spectrum-based strategies and achieve a higher classification accuracy. The proposed TRMSC model may be helpful for portable sleep analyzers and provide a new analytical method for clinical sleeping research.

Compared to civilians and non-medical personnel, military medical doctors are at increased risk for sleep disturbances and impaired psychological well-being. Despite their responsibility and workload, no research has examined sleep disturbances and psychological well-being among the medical doctors (MDs) of the Swiss Armed Forces (SAF). Thus, the aims of the proposed study are (1) to conduct a cross-sectional study (labeled 'Survey-Study 1') of sleep disturbances and psychological well-being among MDs of the SAF; (2) to identify MDs who report sleep disturbances (insomnia severity index >8), along with low psychological well-being such as symptoms of depression, anxiety and stress, but also emotion regulation, concentration, social life, strengths and difficulties, and mental toughness both in the private/professional and military context and (3) to offer those MDs with sleep disturbances an evidence-based and standardized online interventional group program of cognitive behavioral therapy for insomnia (eCBTi) over a time lapse of 6 weeks (labeled 'Intervention-Study 2').

All MDs serving in the SAF (N = 480) will be contacted via the SAF-secured communication system to participate in a cross-sectional survey of sleep disturbances and psychological well-being ('Survey-Study 1'). Those who consent will be provided a link to a secure online survey that assesses sleep disturbances and psychological well-being (depression, anxiety, stress, coping), including current working conditions, job-related quality of life, mental toughness, social context, family/couple functioning, substance use, and physical activity patterns. Baseline data will be screened to identify those MDs who report sleep disturbances (insomnia severity index >8); they will be re-contacted, consented, and randomly assigned either to the eCBTi or the active control condition (ACC) ('Intervention-Study 2'). Individuals in the intervention condition will participate in an online standardized and evidence-based group intervention program of cognitive behavioral therapy for insomnia (eCBTi; once the week for six consecutive weeks; 60-70 min duration/session). Participants in the ACC will participate in an online group counseling (once the week for six consecutive weeks; 60-70 min duration/session), though, the ACC is not intended as a bona fide psychotherapeutic intervention. At the beginning of the intervention (baseline), at week 3, and at week 6 (post-intervention) participants complete a series of self-rating questionnaires as for the Survey-Study 1, though with additional questionnaires covering sleep-related cognitions, experiential avoidance, and dimensions of self-awareness.

Survey-Study 1: We expect to describe the prevalence rates of, and the associations between sleep disturbances (insomnia (sleep quality); sleep onset latency (SOL); awakenings after sleep onset (WASO)) and psychological well-being among MDs of the SAF; we further expect to identify specific dimensions of psychological well-being, which might be rather associated or non-associated with sleep disturbances.Intervention-Study 2: We expect several significant condition-by-time-interactions. Such that participants in the eCBTi will report significantly greater improvement in sleep disturbances, symptoms of depression, anxiety, stress reduction both at work and at home (family related stress), and an improvement in the overall quality of life as compared to the ACC over the period of the study.

The study offers the opportunity to understand the prevalence of sleep disturbances, including factors of psychological well-being among MDs of the SAF. Further, based on the results of the Intervention-Study 2, and if supported, eCBTi may be a promising method to address sleep disturbances and psychological well-being among the specific context of MDs in the SAF.

Empirical investigations that search for a link between dreaming and sleep-dependent memory consolidation have focused on testing for an association between dreaming of what was learned, and improved memory performance for learned material. Empirical support for this is mixed, perhaps owing to the inherent challenges presented by the nature of dreams, and methodological inconsistencies. The purpose of this paper is to address critically prevalent assumptions and practices, with the aim of clarifying and enhancing research on this topic, chiefly by providing a theoretical synthesis of existing models and evidence. Also, it recommends the method of Targeted Memory Reactivation (TMR) as a means for investigating if dream content can be linked to specific cued activations. Other recommendations to enhance research practice and enquiry on this subject are also provided, focusing on the HOW and WHY we search for memory sources in dreams, and what purpose (if any) they might serve.

In children and adolescents with epilepsy (CAWE), disturbed sleep and functional difficulties are frequently present, but their relationship is unclear. In this scoping review we aimed to explore associations between sleep and functional outcomes in CAWE.

We registered the protocol with open science framework and conducted the review according to the PRISMA Extension for Scoping Reviews. We searched Medline, Embase, PsycINFO and PubMed for original studies reporting on relations between sleep and functional outcomes (adaptive/quality of life, behavioural/mood, cognitive & academic) in CAWE. To assess the quality of studies we used an extended version of the checklist employed by Winsor and colleagues [1].

We identified 14 studies that included 1,785 CAWE and 1,260 control children, with a mean age of 9.94 and 10.13 years, respectively. The studies were highly heterogeneous with respect to samples, epilepsy variables, and methods used to assess sleep and functional outcomes. The quality of studies was medium. Associations between sleep and adaptive/quality of life, behavioural/mood, cognitive and academic outcomes were examined in 2, 10, 6, and 0 studies, respectively. Across studies, in CAWE, greater sleep disturbances were related to worse behavioural/mood outcomes, ranging from depression/anxiety to ADHD symptoms. Sleep disturbances did not consistently relate to cognitive outcomes, but they related to worse adaptive outcomes in both studies that examined their relationship.

Our study provides evidence of relationship between disturbed sleep and behavioural/mood difficulties, which alerts to the need for careful evaluation and treatment of sleep disturbances in CAWE. Our study also highlights the need to examine relationships between sleep and other functional outcomes in CAWE, as studies conducted in the general population suggest that sleep disturbances may be modifiable and associated with improved functional outcomes.

Previous studies have reported the success of distributional learning for adult speakers across segmental and suprasegmental categories immediately after training. On the other hand, second language (L2) perception models posit that the ease with which learners perceive a nonnative speech contrast depends on the perceptual mapping between the contrast and learners' first language (L1) categories. This study examined whether a difference in perceptual mapping patterns for different L2-Mandarin tonal contrasts might result in a difference in distributional learning effectiveness for tonal speakers and whether an interval of sleep enhanced the knowledge through consolidation.

Following a pretest-training-posttest design, 66 L1-Cantonese participants with fewer than 9 years of Mandarin training were assigned to either the bimodal or unimodal distribution conditions. The participants of each group were asked to discriminate Mandarin level-falling (T1-T4) and level-rising (T1-T2) tone pairs on novel syllables in a within-subject design. All participants were trained in the evening, tested after training, and returned after 12 hr for overnight consolidation assessment.

A significant distributional learning effect was observed for Mandarin T1-T4, but only after sleep. No significant distributional learning effect was observed for Mandarin T1-T2, either after training or after sleep.

The findings may imply that distributional learning is contingent on perceptual mapping patterns of the target contrasts and that sleep may play a role in the consolidation of knowledge in an implicit statistical learning paradigm.

https://doi.org/10.23641/asha.25970008.

Learning how others perceive us helps us tune our behavior to form adaptive relationships. But which perceptions stick with us? And when in the learning process are they codified in memory? We leveraged a popular television series-The Office-to answer these questions. Prior to their functional magnetic resonance imaging (fMRI) session, viewers of The Office reported which characters they identified with, as well as which characters they perceived another person (i.e. counterpart) was similar to. During their fMRI scan, participants found out which characters other people thought they and the counterpart were like, and also completed rest scans. Participants remembered more feedback inconsistent with their self-views (vs. views of the counterpart). Although neural activity while encoding self-inconsistent feedback did not meaningfully predict memory, returning to the inconsistent self feedback during subsequent rest did. During rest, participants reinstated neural patterns engaged while receiving self-inconsistent feedback in the dorsomedial prefrontal cortex (DMPFC). DMPFC reinstatement also quadratically predicted self-inconsistent memory, with too few or too many reinstatements compromising memory performance. Processing social feedback during rest may impact how we remember and integrate the feedback, especially when it contradicts our self-views.

Neuronal ensembles are crucial for episodic memory and spatial mapping. Sleep, particularly non-REM (NREM), is vital for memory consolidation, as it triggers plasticity mechanisms through brain oscillations that reactivate neuronal ensembles. Here, we assessed their role in consolidating hippocampal spatial representations during sleep. We recorded hippocampus activity in rats performing a spatial object-place recognition (OPR) memory task, during encoding and retrieval periods, separated by intervening sleep. Successful OPR retrieval correlated with NREM duration, during which cortical oscillations decreased in power and density as well as neuronal spiking, suggesting global downregulation of network excitability. However, neurons encoding specific spatial locations (i.e., place cells) or objects during OPR showed stronger synchrony with brain oscillations compared to non-encoding neurons, and the stability of spatial representations decreased proportionally with NREM duration. Our findings suggest that NREM sleep may promote flexible remapping in hippocampal ensembles, potentially aiding memory consolidation and adaptation to novel spatial contexts.

Normative models of synaptic plasticity use computational rationales to arrive at predictions of behavioral and network-level adaptive phenomena. In recent years, there has been an explosion of theoretical work in this realm, but experimental confirmation remains limited. In this review, we organize work on normative plasticity models in terms of a set of desiderata that, when satisfied, are designed to ensure that a given model demonstrates a clear link between plasticity and adaptive behavior, is consistent with known biological evidence about neural plasticity and yields specific testable predictions. As a prototype, we include a detailed analysis of the REINFORCE algorithm. We also discuss how new models have begun to improve on the identified criteria and suggest avenues for further development. Overall, we provide a conceptual guide to help develop neural learning theories that are precise, powerful, and experimentally testable.

To determine whether certain patients are vulnerable to errant triage decisions immediately after major surgery and whether there are unique sociodemographic phenotypes within overtriaged and undertriaged cohorts.

In a fair system, overtriage of low-acuity patients to intensive care units (ICUs) and undertriage of high-acuity patients to general wards would affect all sociodemographic subgroups equally.

This multicenter, longitudinal cohort study of hospital admissions immediately after major surgery compared hospital mortality and value of care (risk-adjusted mortality/total costs) across 4 cohorts: overtriage (N = 660), risk-matched overtriage controls admitted to general wards (N = 3077), undertriage (N = 2335), and risk-matched undertriage controls admitted to ICUs (N = 4774). K-means clustering identified sociodemographic phenotypes within overtriage and undertriage cohorts.

Compared with controls, overtriaged admissions had a predominance of male patients (56.2% vs 43.1%, P < 0.001) and commercial insurance (6.4% vs 2.5%, P < 0.001); undertriaged admissions had a predominance of Black patients (28.4% vs 24.4%, P < 0.001) and greater socioeconomic deprivation. Overtriage was associated with increased total direct costs [$16.2K ($11.4K-$23.5K) vs $14.1K ($9.1K-$20.7K), P < 0.001] and low value of care; undertriage was associated with increased hospital mortality (1.5% vs 0.7%, P = 0.002) and hospice care (2.2% vs 0.6%, P < 0.001) and low value of care. Unique sociodemographic phenotypes within both overtriage and undertriage cohorts had similar outcomes and value of care, suggesting that triage decisions, rather than patient characteristics, drive outcomes and value of care.

Postoperative triage decisions should ensure equality across sociodemographic groups by anchoring triage decisions to objective patient acuity assessments, circumventing cognitive shortcuts and mitigating bias.

Altered brain network profiles in schizophrenia (SCZ) during memory consolidation are typically observed during task-active periods such as encoding or retrieval. However active processes are also sub served by covert periods of memory consolidation. These periods are active in that they allow memories to be recapitulated even in the absence of overt sensorimotor processing. It is plausible that regions central to memory formation like the dlPFC and the hippocampus, exert network signatures during covert periods. Are these signatures altered in patients? The question is clinically relevant because real world learning and memory is facilitated by covert processing, and may be impaired in schizophrenia. Here, we compared network signatures of the dlPFC and the hippocampus during covert periods of a learning and memory task. Because behavioral proficiency increased non-linearly, functional connectivity of the dlPFC and hippocampus [psychophysiological interaction (PPI)] was estimated for each of the Early (linear increases in performance) and Late (asymptotic performance) covert periods. During Early periods, we observed hypo-modulation by the hippocampus but hyper-modulation by dlPFC. Conversely, during Late periods, we observed hypo-modulation by both the dlPFC and the hippocampus. We stitch these results into a conceptual model of network deficits during covert periods of memory consolidation.

Individuals with neurodevelopmental disorders experience persistent sleep deficits, and there is increasing evidence that sleep dysregulation is an underlying cause, rather than merely an effect, of the synaptic and behavioral defects observed in these disorders. At the molecular level, dysregulation of the synaptic proteome is a common feature of neurodevelopmental disorders, though the mechanism connecting these molecular and behavioral phenotypes is an ongoing area of investigation. A role for eIF2α in shifting the local proteome in response to changes in the conditions at the synapse has emerged. Here, we discuss recent progress in characterizing the intersection of local synaptic translation and sleep and propose a reciprocal mechanism of dysregulation in the development of synaptic plasticity defects in neurodevelopmental disorders.

Sleep supports systems memory consolidation through the precise temporal coordination of specific oscillatory events during slow-wave sleep, i.e. the neocortical slow oscillations (SOs), thalamic spindles, and hippocampal ripples. Beneficial effects of sleep on memory are also observed in infants, although the contributing regions, especially hippocampus and frontal cortex, are immature. Here, we examined in rats the development of these oscillatory events and their coupling during early life.

EEG and hippocampal local field potentials were recorded during sleep in male rats at postnatal days (PD)26 and 32, roughly corresponding to early (1-2 years) and late (9-10 years) human childhood, and in a group of adult rats (14-18 weeks, corresponding to ~22-29 years in humans).

SO and spindle amplitudes generally increased from PD26 to PD32. In parallel, frontocortical EEG spindles increased in density and frequency, while changes in hippocampal ripples remained nonsignificant. The proportion of SOs co-occurring with spindles also increased from PD26 to PD32. Whereas parietal cortical spindles were phase-locked to the depolarizing SO-upstate already at PD26, over frontal cortex SO-spindle phase-locking emerged not until PD32. Co-occurrence of hippocampal ripples with spindles was higher during childhood than in adult rats, but significant phase-locking of ripples to the excitable spindle troughs was observed only in adult rats.

Results indicate a protracted development of synchronized thalamocortical processing specifically in frontocortical networks (i.e. frontal SO-spindle coupling). However, synchronization within thalamocortical networks generally precedes synchronization of thalamocortical with hippocampal processing as reflected by the delayed occurrence of spindle-ripple phase-coupling.