Sleep-dependent learning and memory consolidation

Promotion of sleep by cinnamic acid in parachlorophenylalanine-induced insomnia in rats

PURPOSE

This study aimed to examine the efficacy and underlying mechanisms of action of cinnamic acid (CA) in the treatment of insomnia.

METHODS

An insomnia model was established using parachlorophenylalanine (PCPA) in rats. Pathological changes in the rat hippocampal CA3 region were assessed using hematoxylin and eosin staining. Sleep duration and sleep-wake states were assessed using a pentobarbital-induced sleep test and electroencephalogram analysis. Neurotransmitters, including 5-hydroxytryptophan (5-HTP), 5-hydroxy tryptamine (5-HT), γ-aminobutyric acid (GABA), and glutamic acid (Glu), were detected via enzyme-linked immunosorbent assay. Changes in glutamic acid decarboxylase (GAD)67, GABAAR γ2, GABAAR β2, and GABAAR α proteins were assessed using western blotting. Bulk RNA sequencing (RNA-seq) analysis and molecular docking were used to explore the mechanism of action of CA in insomnia treatment.

RESULTS

In the rat model with PCPA-induced insomnia, CA treatment increased body weight and food intake, reduced water intake, and alleviated damage to the hippocampal CA3 region. CA treatment also reduced sleep latency and wake time and enhanced sleep duration, rapid eye movement sleep, and non-rapid eye movement sleep. In the hypothalamus, CA treatment increased 5-HTP, 5-HT, GABA, GAD67, GABAAR γ2, GABAAR β2, and GABAAR α1 levels, but reduced Glu levels. Using the data from bulk RNA-seq, GSEA analysis indicated neurotrophin signaling pathway was activated by CA treatment. CA could bind with LHPP and reduced its protein expression.

CONCLUSION

CA treatment prolonged sleep duration and improved sleep quality in a rat model of insomnia, mediated by LHPP inhibition.

Exploring Lifestyles and Sensory Processing Patterns of Toddlers in Relation to Sleep Patterns Using Body Movement Analysis

This study explored the impact of lifestyle habits and sensory processing patterns on sleep quality by analyzing body movements (BMs) during the first and last 3 h of sleep in toddlers. We collected cross-sectional data about sleep-related habits from 58 toddlers using a mobile application. Actigraphy measured BMs during nighttime sleep and 1 h before bedtime, as well as sleep latency, over 8 consecutive days. The Infant/Toddler Sensory Profile was used to assess the toddlers' sensory processing patterns. The participants had a mean age of 22.0 ± 2.0 months. BMs were significantly lower during the first 3 h of sleep. Longer sleep latency was significantly associated with media use and higher activity levels before bedtime. Ending a nap earlier and consuming a substantial breakfast were correlated with lower BMs during the first 3 h of sleep. Auditory and oral sensory scores were positively correlated with BMs during the first 3 h of sleep. However, no specific factors related to lifestyle habits or sensory processing patterns were found to correlate with BMs during the last 3 h of sleep. Lifestyle habits and sensory processing patterns have a significant impact on toddlers' sleep quality, emphasizing the importance of appropriate routines and environments.

CB-1 receptor agonist drastically changes oscillatory activity, defining active sleep

Brain oscillations in different behavioral states are essential for cognition, and oscillopathies contribute to cognitive dysfunction in neuropsychiatric diseases. Cannabis-1 receptor (CB1-R) activation was reported to suppress theta and fast gamma activities in rats during waking exploration, and here, we show that cannabis fundamentally alters network activity during sleep as well. Prominent theta rhythm is present in rapid eye movement sleep (REMS), whereas fast oscillations appear as regular sequences of sleep spindles during intermediate sleep (IS)-both implicated in dreaming and memory consolidation. The CB1-R agonist disrupted these mechanisms, restructuring IS-REMS episodes; IS lengthened sixfold and intruded REMS, where ongoing theta was drastically reduced. The spindle architecture was also affected; its amplitude increased, and its peak frequency downshifted into the theta range. Cannabis is known to induce psychotic-like conditions and cognitive deficits; thus, our results may help in understanding the dual effect of cannabis on cognitive states and the role of network oscillations in psychiatric pathology.

Impact of spindle-inspired transcranial alternating current stimulation during a nap on sleep-dependent motor memory consolidation in healthy older adults

With the increase in life expectancy and the rapid evolution of daily life technologies, older adults must constantly learn new skills to adapt to society. Sleep reinforces skills acquired during the day and is associated with the occurrence of specific oscillations such as spindles. However, with age, spindles deteriorate and thus likely contribute to memory impairments observed in older adults. The application of electric currents by means of transcranial alternating current stimulation (tACS) with spindle-like waveform, applied during the night, was found to enhance spindles and motor memory consolidation in young adults. Here, we tested whether tACS bursts inspired by spindles applied during daytime naps may (i) increase spindle density and (ii) foster motor memory consolidation in older adults. Twenty-six healthy older participants performed a force modulation task at 10:00, were retested at 16:30, and the day after the initial training. They had 90-minute opportunity to take a nap while verum or placebo spindle-inspired tACS bursts were applied with similar temporal parameters to those observed in young adults and independently of natural spindles, which are reduced in the elderly. We show that the density of natural spindles correlates with the magnitude of memory consolidation, thus confirming that spindles are promising physiological targets for enhancing memory consolidation in older adults. However, spindle-inspired tACS, as used in the present study, did not enhance either spindles or memory consolidation. We therefore suggest that applying tACS time-locked to natural spindles might be required to entrain them and improve their related functions.

The influence of sleep disruption on learning and memory in fish

Sleep is a ubiquitous process that has been conserved in animals. Yet, our understanding of the functions of sleep largely derives from a few species. Sleep is considered to play an important role in mental processes, including learning and memory consolidation, but how widespread this relationship is across taxa remains unclear. Here, we test the impact of sleep disruption on the ability of the cleaner fish (Labroides dimidiatus) to both learn and remember a novel cognitive task. Sleep was disrupted by exposing a subset of fish to light at set intervals during the night. We found a significant negative relationship between sleep disruption and the ability to learn a novel task. Specifically, we found that fish in the light-disturbed sleep treatment took significantly longer and made more incorrect decisions to find a food reward, compared with the undisturbed sleep treatment. All fish were then allowed a normal sleep schedule and retested several days later to assess their ability to remember the task. In contrast to the learning phase, we observed no significant differences between the two treatment groups in remembering the food reward several days later. Our results demonstrate a negative impact of sleep disruption on performance in a cognitive challenging task that appeared to have the strongest effect when fish were first exposed to the challenge. Importantly, we show that the association between sleep and mental processes, such as learning, may be widespread across vertebrate taxa and potentially have an early origin in the evolutionary history of vertebrate animals.

The Effect of Suvorexant on Fear Extinction Recall: A Double-Blind Randomised Controlled Pilot Trial in Healthy Individuals

Post-traumatic stress disorder (PTSD) is a highly debilitating condition that develops after trauma exposure. Dysregulation in extinction memory consolidation (i.e., the ability to remember that trauma-related stimuli no longer signal danger) is proposed to underlie PTSD development. Disruptions in rapid eye movement (REM) sleep are thought to be the key contributor to this dysregulation, as REM sleep is suggested to play a vital role in the processing of emotional memories. While previous literature has investigated the role of natural REM sleep variations or REM sleep disruptions on extinction recall capacities, none have attempted to increase REM sleep to improve extinction recall. In this pilot, randomised controlled trial, we investigated the effect of 20 mg suvorexant to increase REM sleep, 20 mg temazepam to decrease REM sleep, and a placebo on extinction recall in 30 healthy adults (age: M = 26.93 years, SD = 7.54). Overall, no difference in REM percentage (p = 0.68, η2 = 0.0.03, small effect), nor in extinction recall (p = 0.58, η2 = 0.04, small effect) was observed between the drug conditions. However, increased REM percentage was associated with decreased conditioned fear response at recall, indicating better extinction recall (β = -0.71, p = 0.03, ηp 2 = 0.10; moderate effect) across the sample. These findings suggest that increasing REM sleep in populations with REM disruptions such as PTSD to optimal levels could improve extinction recall. This underscores the potential of enhancing REM sleep as a therapeutic target for improving PTSD outcomes, warranting further investigation of suvorexant in clinical populations where REM sleep deficits are prevalent.

A Self-Adaptive Serious Game to Improve Motor Learning Among Older Adults in Immersive Virtual Reality: Short-Term Longitudinal Pre-Post Study on Retention and Transfer

BACKGROUND

Despite their potential, the use of serious games within immersive virtual reality (iVR) for enhancing motor skills in older adults remains relatively unexplored. In this study, we developed a self-adaptive serious game in iVR called REAsmash-iVR. This game involves swiftly locating and striking a digital mole presented with various distractors.

OBJECTIVE

This short-term longitudinal pre-post study aims to evaluate REAsmash-iVR's efficacy in promoting motor learning in older adults. Specifically, we seek to determine the transfer and retention of motor learning achieved through REAsmash-iVR to other iVR tasks.

METHODS

A total of 20 older adults participated in the study, engaging with REAsmash-iVR over 7 consecutive days. The evaluation included iVR tests such as KinematicsVR and a VR adaptation of the Box and Block Test (BBT-VR). KinematicsVR tasks included drawing straight lines and circles as fast and as accurately as possible, while BBT-VR required participants to move digital cubes as quickly as possible within 60 seconds. Assessments were conducted before and after the intervention, with a follow-up at 1 week post intervention. The primary outcome focused on evaluating the impact of REAsmash-iVR on speed-accuracy trade-off during KinematicsVR tasks. Secondary outcomes included analyzing movement smoothness, measured by spectral arc length, and BBT-VR scores.

RESULTS

Results revealed significant improvements in speed-accuracy trade-off post intervention compared to that before the intervention, with notable retention of skills for straight lines (t19=5.46; P<.001; Cohen d=1.13) and circle drawing (t19=3.84; P=.001; Cohen d=0.787). Likewise, there was a significant enhancement in spectral arc length, particularly for circle drawing (χ²2=11.2; P=.004; ε2=0.23), but not for straight-line drawing (χ²2=2.1; P=.35; ε2=0.003). Additionally, participants demonstrated transfer with significant improvement (q=5.26; P<.001; Cohen r=0.678) and retention (q=6.82; P<.001; Cohen r=0.880) in BBT-VR skills.

CONCLUSIONS

These findings provide perspectives for the use of iVR to improve motor learning in older adults through delivering self-adaptive serious games targeting motor and cognitive functions.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04694833; https://clinicaltrials.gov/study/NCT04694833.

Highly Superior Autobiographical Memory (HSAM): A Systematic Review

Individuals possessing a Highly Superior Autobiographical Memory (HSAM) demonstrate an exceptional ability to recall their own past, excelling most when dates from their lifetime are used as retrieval cues. Fully understanding how neurocognitive mechanisms support exceptional memory could lead to benefits in areas of healthcare in which memory plays a central role and in legal fields reliant on witnesses' memories. Predominantly due to the rareness of the phenomenon, existing HSAM literature is highly heterogenous in its methodologies used. Therefore, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we performed the first systematic review on this topic, to collate the existing behavioural, neuroanatomical, and functional HSAM data. Results from the 20 experimental selected studies revealed that HSAM is categorised by rapidly retrieved, detailed and accurate autobiographical memories, and appears to avoid the normal aging process. Functional neuroimaging studies showed HSAM retrieval seems characterised by an intense overactivation of the usual autobiographical memory network, including posterior visual areas (e.g., the precuneus). Structural neuroanatomical differences do not appear to characterise HSAM, but altered hippocampal resting-state connectivity was commonly observed. We discuss theories of HSAM in relation to autobiographical encoding, consolidation, and retrieval, and suggest future directions for this research.

A spectrum of altered non-rapid eye movement sleep in schizophrenia

Multiple facets of sleep neurophysiology, including electroencephalography (EEG) metrics such as non-rapid eye movement (NREM) spindles and slow oscillations, are altered in individuals with schizophrenia (SCZ). However, beyond group-level analyses, the extent to which NREM deficits vary among patients is unclear, as are their relationships to other sources of heterogeneity including clinical factors, aging, cognitive profiles, and medication regimens. Using newly collected high-density sleep EEG data on 103 individuals with SCZ and 68 controls, we first sought to replicate our previously reported group-level differences between patients and controls (original N = 130) during the N2 stage. Then in the combined sample (N = 301 including 175 patients), we characterized patient-to-patient variability. We replicated all group-level mean differences and confirmed the high accuracy of our predictive model (area under the receiver operating characteristic curve [AUC] = 0.93 for diagnosis). Compared to controls, patients showed significantly increased between-individual variability across many (26%) sleep metrics. Although multiple clinical and cognitive factors were associated with NREM metrics, collectively they did not account for much of the general increase in patient-to-patient variability. The medication regimen was a greater contributor to variability. Some sleep metrics including fast spindle density showed exaggerated age-related effects in SCZ, and patients exhibited older predicted biological ages based on the sleep EEG; further, among patients, certain medications exacerbated these effects, in particular olanzapine. Collectively, our results point to a spectrum of N2 sleep deficits among SCZ patients that can be measured objectively and at scale, with relevance to both the etiological heterogeneity of SCZ as well as potential iatrogenic effects of antipsychotic medication.

Increase in slow frequency and decrease in alpha and beta power during post-learning rest predict long-term memory success

Formation of episodic memories is linked to cortico-hippocampal interactions during learning, practice, and post-learning rest, although the role of cortical activity itself in such processes remains elusive. Behaviorally, long-term retention of episodic memories has been shown to be aided by several different practice strategies involving memory reencounters, such as repeated retrieval and repeated study. In a two-session resting state electroencephalography (EEG) experiment, using data from 68 participants, we investigated the electrophysiological predictors of long-term memory success in situations where such reencounters occurred after learning. Participants learned word pairs which were subsequently practiced either by cued recall or repeated studying in a between-subjects design. Participants' cortical activity was recorded before learning (baseline) and after practice during 15-min resting periods. Long-term memory retention after a 7-day period was measured. To assess cortical activity, we analyzed the change in spectral power from the pre-learning baseline to the post-practice resting state recordings. From baseline to post-practice, changes in alpha and beta power were negatively, while slow frequency power change was positively associated with long-term memory performance, regardless of practice strategy. These results are in line with previous observations pointing to the role of specific frequency bands in memory formation and extend them to situations where memory reencounters occur after learning. Our results also highlight that the effectiveness of practice by repeated testing seems to be independent from the beneficial neural mechanisms mirrored by EEG frequency power changes.

Association between infant sleep and neurodevelopment in a prospective birth cohort study

OBJECTIVES

To investigate the association of infant sleep and sleep trajectories through the first year of life with infant neurodevelopment.

METHODS

This study was conducted with 3251 infants in China. Sleep parameters were evaluated by the Brief Infant Sleep Questionnaire at 42days, 6months, and 1year of age. Neurodevelopment was evaluated at 1year of age using the Bayley Scales of Infant and Toddler Development, Third Edition. The latent variable growth curve model was used to evaluate the developmental trajectories of infant sleep, including total sleep duration trajectories, night awakening trajectories and sleep onset latency trajectories. Poisson regression was applied to assess the association between sleep parameters and sleep trajectories and infant neurodevelopment.

RESULTS

Infants with frequent night awakenings at 6months had a higher risk of nonoptimal gross motor development. Additionally, infants with prolonged sleep onset latency at 1year had an increased risk of nonoptimal fine and gross motor development. A consistent frequent night-awakening trajectory increased the risk of nonoptimal gross motor development (adjusted relative risk, 1.52; 95% confidence interval, 1.09 to 2.10). Furthermore, an increasing trajectory in sleep onset latency was associated with an increased risk of nonoptimal fine (adjusted relative risk, 2.70; 95% confidence interval, 1.12 to 6.51) and gross motor development (adjusted relative risk, 2.76; 95% confidence interval, 1.70 to 4.48). However, no significant association was observed between total sleep duration, or its trajectory, and infant neurodevelopment.

CONCLUSIONS

Sleep problems or specific sleep trajectories during the initial year of life may increase risk of compromised neurodevelopment.

Bilingualism, sleep, and cognition: An integrative view and open research questions

Sleep and language are fundamental to human existence and have both been shown to substantially affect cognitive functioning including memory, attentional performance, and cognitive control. Surprisingly, there is little-to-no research that examines the shared impact of bilingualism and sleep on cognitive functions. In this paper, we provide a general overview of existing research on the interplay between bilingualism and sleep with a specific focus on executive functioning. First, we highlight their interconnections and the resulting implications for cognitive performance. Second, we emphasize the need to explore how bilingualism and sleep intersect at cognitive and neural levels, offering insights into potential ways of studying the interplay between sleep, language learning, and bilingual language use. Finally, we suggest that understanding these relationships could enhance our knowledge of reserve and its role in mitigating age-related cognitive decline.

Oral administration of ethinyl estradiol and the brain-selective estrogen prodrug DHED in a female common marmoset model of menopause: Effects on cognition, thermoregulation, and sleep

Menopausal symptoms of sleep disturbances, cognitive deficits, and hot flashes are understudied, in part due to the lack of animal models in which they co-occur. Common marmosets (Callithrix jacchus) are valuable nonhuman primates for studying these symptoms, and we examined changes in cognition (reversal learning), sleep (48 h/wk of sleep recorded by telemetry), and thermoregulation (nose temperature in response to mild external warming) in middle-aged, surgically-induced menopausal marmosets studied at baseline, during 3-week phases of ethinyl estradiol (EE2, 4 μg/kg/day, p.o.) treatment and after EE2 withdrawal. We also assessed a brain-selective hormonal therapy devoid of estrogenic effects in peripheral tissues on the same measures (cognition, sleep, thermoregulation) after treatment with the estrogen prodrug 10β,17β-dihydroxyestra-1,4-dien-3-one (DHED, 100 μg/kg/day, p.o) and DHED withdrawal. Reversal learning performance was improved with EE2 or DHED treatment relative to phases without hormone administration, as indicated by a faster reversal of the stimulus/reward contingencies. Both EE2 and DHED increased non-REM sleep and reduced nighttime awakenings relative to baseline, but to the detriment of REM sleep which was highest at baseline. Nasal temperature in response to mild external warming was highest, and overnight core body temperature lowest, in the DHED treatment phase compared to both the EE2 and baseline phases. These results suggest that low dose estradiol, delivered either peripherally or centrally via DHED, benefits selective aspects of cognition and sleep in a marmoset menopause model. DHED appears a promising therapeutic candidate for alleviating the cognitive and sleep disruptions associated with estrogen deficiency in primates.

The effects of sleep deprivation on the balance system: following normal sleep, 24 h of sleep deprivation, and rest under eyes-open and eyes-closed conditions

OBJECTIVE

This study investigated the effects of sleep deprivation (SD) on balance after normal sleep, 24 h of SD, and subsequent rest under eyes-open (EO) and eyes-closed (EC) conditions. Our aim was to ascertain whether the reduced efficiency of balance control following SD is generalized or selective.

METHOD

Nineteen participants (12 females, 7 males) completed the Pittsburgh Sleep Quality Index (PSQI). The mean ages for male participants were 24.14 ± 0.37 years, their height was 180.71 ± 5.46 cm, and weight of male participants were 81.71 ± 13.42 kg. For female participants, the mean ages were 24.41 ± 4.01 years, their height was 163.66 ± 2.64 cm, and their weight was 59.54 ± 9.18 kg. Stance analyses were conducted after normal sleep, 24 h of SD, and subsequent rest of both the EO and EC. Participants performed a normal balance test, a second test while holding cubes and counting backwards from 200 by sevens, and a third test after rest under EO and EC.

RESULTS

Independent samples t-tests showed significant height and weight differences between sexes (p < 0.05), with females generally smaller. No significant differences were found in age, daytime sleep duration, or PSQI score (p > 0.05). Significant differences in parameters such as length of the minor axis (lomna), angle, and area were observed in EO and EC across the three days, revealing the interplay between visual stimuli, cognitive tasks, and parameter stability.

CONCLUSION

SD has multifaceted impacts on motor and cognitive performance, even when attentional and sensory resources are not strained. Our findings elucidate the nuanced impact of SD on cognitive performance, and suggest the efficacy of external factors in mitigating its effects on postural control.

The Effect of Total Sleep Deprivation on the Cognitive and In-Game Performance of Rocket League Esport Players

Purpose

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.

Patients and Methods

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).

Results

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.

Conclusion

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.

Does fragmented sleep mediate the relationship between deficits in sleep spindles and memory consolidation in schizophrenia?

Study Objectives

Sleep spindles, defining electroencephalographic oscillations of nonrapid eye movement (NREM) stage 2 sleep (N2), mediate sleep-dependent memory consolidation (SDMC). Spindles are also thought to protect sleep continuity by suppressing thalamocortical sensory relay. Schizophrenia is characterized by spindle deficits and a correlated reduction of SDMC. We investigated whether this relationship is mediated by sleep fragmentation.

Methods

We detected spindles (12-15 Hz) during N2 at central electrodes in overnight polysomnography records from 56 participants with chronic schizophrenia and 59 healthy controls. Our primary measures of sleep continuity were the sleep fragmentation index and, in a subset of the data, visually scored arousals. SDMC was measured as overnight improvement on the finger-tapping motor sequence task.

Results

Participants with schizophrenia showed reductions of both spindle density (#/min) and SDMC in the context of normal sleep continuity and architecture. Spindle density predicted SDMC in both groups. In contrast, neither increased sleep fragmentation nor arousals predicted lower spindle density or worse SDMC in either group.

Conclusions

Our findings fail to support the hypothesis that sleep fragmentation accounts for spindle deficits, impaired SDMC, or their relationship in individuals with chronic schizophrenia. Instead, our findings are consistent with the hypothesis that spindle deficits directly impair memory consolidation in schizophrenia. Since sleep continuity and architecture are intact in this population, research aimed at developing interventions should instead focus on understanding dysfunction within the thalamocortical-hippocampal circuitry that both generates spindles and synchronizes them with other NREM oscillations to mediate SDMC.

Sleep-improving effect and the potential mechanism of Morus alba L. on mice

As insufficient sleep has become a widespread concern in modern society, potential sleep-improving effect of mulberry (Morus alba L.) leaf ethanol extract (MLE) and the related mechanism were investigated in the present study. According to the results, MLE could significantly shorten sleep latency by 33 %, extend sleep duration by 56 % and increase sleep ratio of mice through increasing 5-HT and GABA release in serum, hypothalamus and hippocampus. Metabonomic analysis showed that phenylalanine metabolism, arginine and proline metabolism might be the potential pathways of MLE to improve sleep. Network pharmacological and LC-MS analysis suggested that the key sleep-improving active ingredients in MLE might be luteolin, kaempferol, naringenin, morin, stigmasterol and β-sitosterol. Further molecular docking and qRT-PCR results demonstrated that the key targets for MLE to improve sleep might be MAOA, GABRA1 and GABRA2. In conclusion, MLE showed outstanding sleep-improving effect and great potential for the application as novel sleep-improving functional food.

A systematic and meta-analytic review of the impact of sleep restriction on memory formation

Modern life causes a quarter of adults and half of teenagers to sleep for less than is recommended (Kocevska et al., 2021). Given well-documented benefits of sleep on memory, we must understand the cognitive costs of short sleep. We analysed 125 sleep restriction effect sizes from 39 reports involving 1234 participants. Restricting sleep (3-6.5 hours) compared to normal sleep (7-11 hours) negatively affects memory formation with a small effect size (Hedges' g = 0.29, 95 % CI = [0.13, 0.44]). We detected no evidence for publication bias. When sleep restriction effect sizes were compared with 185 sleep deprivation effect sizes (Newbury et al., 2021) no statistically significant difference was found, suggesting that missing some sleep has similar consequences for memory as not sleeping at all. When the analysis was restricted to post-encoding, rather than pre-encoding, sleep loss, sleep deprivation was associated with larger memory impairment than restriction. Our findings are best accounted for by the sequential hypothesis which emphasises complementary roles of slow-wave sleep and REM sleep for memory.

Regular sleep habits in toddlers are associated with social development and brain coherence

OBJECTIVE

Although sleep habits are associated with the development of toddlers, factors affecting social development and brain function remain unclear. We aimed to elucidate the relationship between sleep habits and social development as well as brain coherence in toddlers.

METHODS

We used the data set at 1.5-2 years old, in the longitudinal study until 6 years old. We evaluated sleep parameters, such as average wake-up time, bedtime, nighttime sleep duration, total sleep duration, and the standard deviation (SD) of sleep habits. We also examined the development, including the social stimuli fixation percentage using Gazefinder® and electroencephalography (EEG) coherence between brain regions.

RESULTS

Seventy-two children (37 boys and 35 girls) were included. The fixation percentage for the human face was negatively correlated with the SD of the total sleep duration, nighttime sleep duration, nap duration, and bedtime (r = -0.516, p = 0.000; r = -0.331, p = 0.005; r = -0.330, p = 0.005; and r = -0.324, p = 0.005, respectively). The EEG analysis indicated that α-band coherence in the right centro-parietal area was negatively correlated with the total sleep duration (r = -0.283, p = 0.016). The path diagram demonstrated a direct significant effect of sleep duration irregularity on development including social communication and fixation percentage for human faces. Additionally, total sleep duration exhibited a direct effect on α cortical coherence in the right centro-parietal area.

CONCLUSIONS

In this study, we found an association between sleep irregularity and the development of social communication, preference for humans, and brain coherence in toddlers. We suggest that regular sleep plays an important role in promoting the development of social communication.

A genome-wide methylation analysis of Chinese Han patients with chronic insomnia disorder

BACKGROUND

As the most common sleep disorder, chronic insomnia disorder (CID) has become a global health burden to the public. However, it remains unclear about the pathogenesis of this disease. Epigenetic changes may provide important insights into the gene-environment interaction in CID. Therefore, this study was conducted to investigate the DNA methylation pattern in CID and reveal the epigenetic mechanism of this disease.

METHODS

In this study, whole blood DNA was extracted from 8 CID patients (the CID group) and 8 healthy controls (the control group), respectively. Besides, genome-wide DNA methylation was detected by Illumina Human Methylation 850 K Beadchip. Moreover, the sleep quality and insomnia severity were evaluated by the Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI), respectively.

RESULTS

A total of 369 differentially methylated positions (DMPs) and 23 differentially methylated regions (DMRs) were identified between the CID and control groups. LHX6 was identified as the most important differentially methylated gene (DMG). The Gene Ontology (GO) analysis results corroborated that DMPs were significantly enriched in 105 GO terms, including cell signaling, homogenous cell adhesion of plasma membrane adhesion molecules, nervous system development, cell adhesion, and calcium ion binding. In addition, it was demonstrated that DMPs were significantly enriched in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including the hippo signaling pathway, Ras signaling pathway, and vitamin B6 metabolism. The DMR-related GO analysis results revealed the positive regulation of protein kinase activities.

CONCLUSIONS

DNA methylation plays a critical role in the development of CID, and LHX6 is validated to be an important DMG.

Sleep and retrieval practice both strengthen and distort story recollection

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.

Are the Sleep-Wake Cycle and Sleep Duration Ethnically Determined? A Comparison of Tibetan and Japanese Children's Sleep

BACKGROUND

Several environmental factors affect sleep. We investigated the sleep and sleep-related habits of preschool children living in Tibet and conducted an international comparison with those in Japan.

METHODS

We conducted a community-based cross-sectional study using the Chinese version of the Japanese Sleep Questionnaire for Preschoolers (JSQ-P-C) and compared the results with previous data on Japanese children.

RESULTS

The sleep status of 3113 children aged 3-6 years old in Qinghai province was evaluated. The average wake time and bedtime of the Tibetan children were 7:20 ± 0:31 and 21:16 ± 0:43, respectively. Their mean nocturnal sleep duration was 10.0 ± 0.7 h. In comparing 3-year-old children, the time for which they viewed TV in Tibet was shorter (65.5 ± 44.6 min) than that in Japan (149.7 ± 76.6 min), and the mother's bedtime was earlier in Tibet (21:28 ± 2:14) than in Japan (23:20 ± 1:05). However, the bedtime and sleep duration of the Tibetan children (21:17 ± 0:37 and 10.0 ± 0.7 h) were fairly similar to those of the Japanese children (21:24 ± 1:57 and 9.8 ± 0.8 h).

CONCLUSIONS

The late bedtime and short nocturnal sleep duration of Tibetan toddlers were the same as those of Japanese toddlers despite considerable differences in their lifestyle and environment.

Emerging many-to-one weighted mapping in hippocampus-amygdala network underlies memory formation

Memories are crucial for daily life, yet the network-level organizing principles governing neural representations of experiences remain unknown. Employing dual-site in vivo recording in freely behaving male mice, here we show that hippocampal dorsal CA1 (dCA1) and basolateral amygdala (BLA) utilize distinct coding strategies for novel experiences. A small assembly of BLA neurons emerged active during memory acquisition and persisted through consolidation, whereas most dCA1 neurons were engaged in both processes. Machine learning decoding revealed that dCA1 population spikes predicted BLA assembly firing rate, suggesting that most dCA1 neurons concurrently index an episodic event by rapidly establishing weighted communication with a specific BLA assembly - a process we term "many-to-one weighted mapping." We also found that dCA1 reactivations preceded BLA assembly activity preferably during elongated and enlarged dCA1 ripples. Using a closed-loop strategy, we demonstrated that suppressing BLA activity after large dCA1 ripples impaired memory. These findings highlight a many-to-one weighted mapping mechanism underlying both the acquisition and consolidation of new memories.

Restless sleep is associated with increased anxiety in physical therapy students: a cross sectional survey study

BACKGROUND

Sleep and mental health are intimately related and shown to impact graduate students enrolled in health sciences programs, including physical therapy education. Doctorate of Physical Therapy (DPT) students' attitudes and behaviors surrounding sleep and whether these factors are associated with mental health are unknown. This study aimed to describe sleep behaviors and attitudes of entry-level DPT students and to explore the relationship between subjectively reported sleep quality and self-reported symptoms of anxiety in these students.

METHODS

A cross-sectional online survey consisting of the Sleep Practices and Attitudes Questionnaire (SPAQ), the Generalized Anxiety Disorder-7 (GAD-7) questionnaire, and demographic questions were used. Analyses investigated sleep behaviors and attitudes, along with the relationship (unadjusted odds ratio) between restless sleep and anxiety in DPT students in hybrid and traditional DPT programs across the United States (US).

RESULTS

A total of 271 DPT students completed the survey. A majority of students reported feeling tired during most days (80.8%, n = 219), a quarter of participants (24.7%) reported having a history of trouble sleeping and four (1.5%) reported being diagnosed with a sleep disorder. Of those who reported their sleep duration, participants slept an average of 6.86 h. The mean GAD-7 score was 7.68 (SD = 4.90), suggestive of mild anxiety. Sixty-seven (24.7%) reported having a diagnosed anxiety disorder, with generalized anxiety being the most common diagnosis. Those who reported having restless sleep were 4.09 times more likely to have moderate to severe anxiety [unadjusted odds ratio = 4.09 (95% CI 2.27,7.35; p < 0.001)] compared to those who reported restful sleep.

CONCLUSIONS

DPT students who rated sleep as restless exhibit signs of poor subjective sleep quality associated with an increased risk of experiencing moderate to severe anxiety compared to students who had restful sleep. Students reported behaviors surrounding sleep that may contribute to anxiety. These findings have implications for including sleep and mental health education and practices within DPT programs.

Sleep deprivation-induced memory impairment: exploring potential interventions

Sleep's crucial role in memory consolidation is well-established, with neuroimaging and sleep stage analysis revealing the intricate processes involved. Sleep deprivation significantly impairs memory performance and the ability to form new memories, highlighting the need for effective countermeasures. This article concludes that while sleep deprivation significantly impairs memory, the emerging insights into the gut-brain axis offer a promising frontier for developing novel interventions that can mitigate these effects. The review discusses various interventions, ranging from pharmaceutical compounds like donepezil, memantine, and tolcapone, to innovative physical therapy techniques such as transcranial magnetic stimulation (TMS), deep brain stimulation (DBS), and transcranial direct current stimulation (tDCS). Additionally, the emerging role of the gut-brain axis in sleep deprivation-induced memory impairment is examined, shedding light on the complex interplay between gut microbiota and cognitive functions. This comprehensive review explores the multifaceted relationship between sleep deprivation and memory impairment, delving into the neurobiological mechanisms underlying these processes and examining potential interventions.

A visual paired associate learning (vPAL) paradigm to study memory consolidation during sleep

Sleep improves the consolidation and long-term stability of newly formed memories and associations. Most research on human declarative memory and its consolidation during sleep uses word-pair associations requiring exhaustive learning. In the present study, we present the visual paired association learning (vPAL) paradigm, in which participants learn new associations between images of celebrities and animals. The vPAL is based on a one-shot exposure that resembles learning in natural conditions. We tested if vPAL can reveal a role for sleep in memory consolidation by assessing the specificity of memory recognition, and the cued recall performance, before and after sleep. We found that a daytime nap improved the stability of recognition memory and discrimination abilities compared to identical intervals of wakefulness. By contrast, cued recall of associations did not exhibit significant sleep-dependent effects. High-density electroencephalography during naps further revealed an association between sleep spindle density and stability of recognition memory. Thus, the vPAL paradigm opens new avenues for future research on sleep and memory consolidation across ages and heterogeneous populations in health and disease.

Ramadan fasting observance is associated with decreased sleep duration, increased daytime sleepiness and insomnia symptoms among student-athletes

OBJECTIVE

To examine the relationships between Ramadan fasting observance (RFO) and sleep-wake patterns, daytime sleepiness, and insomnia levels in student-athletes.

METHODS

Sleep was measured using wrist-actigraphy in 25 semi-professional student-athletes (mean ± SD; age = 22 ± 2 years, height = 182.0 ± 5.8 cm, body mass = 81.3 ± 15.2 kg) during seven nights before RFO (academic study period), during the first half of RFO (14 nights, holiday period), and the second half of RFO (14 nights, academic study period). Additionally, participants completed the Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI) and Pittsburgh Sleep Quality Index (PSQI) questionnaires seven days before RFO and on the last day of RFO.

RESULTS

Actigraphy results indicated RFO was associated with significant decreases in sleep duration during the second half of RFO vs. before and during the first half of RFO (p < 0.001). However, the first half of RFO was associated with a delay of ⁓ 2.5 h in sleep onset compared to before RFO; this delay persisted during the second half of RFO (p < 0.001). The total PSQI score before RFO (6.6 ± 2.3 AU) and during RFO (8.2 ± 2.3 AU) suggested poor overall sleep quality. ISI and ESS scores were greater during than before RFO (p = 0.002 and p = 0.041, respectively).

CONCLUSIONS

The second half of RFO was associated with decreases in objectively assessed sleep duration among student-athletes. RFO was also associated with impaired sleep quality, excessive daytime sleepiness, and increased insomnia symptoms. Personalized interventions to address sleep-related issues in student-athletes during RFO are warranted.

Review: seizure-related consolidation and the network theory of epilepsy

Epilepsy is a complex, multifaceted disease that affects patients in several ways in addition to seizures, including psychological, social, and quality of life issues, but epilepsy is also known to interact with sleep. Seizures often occur at the boundary between sleep and wake, patients with epilepsy often experience disrupted sleep, and the rate of inter-ictal epileptiform discharges increases during non-REM sleep. The Network Theory of Epilepsy did not address a role for sleep, but recent emphasis on the interaction between epilepsy and sleep suggests that post-seizure sleep may also be involved in the process by which seizures arise and become more severe with time ("epileptogenesis") by co-opting processes related to the formation of long-term memories. While it is generally acknowledged that recurrent seizures arise from the aberrant function of neural circuits, it is possible that the progression of epilepsy is aided by normal, physiological function of neural circuits during sleep that are driven by pathological signals. Studies recording multiple, single neurons prior to spontaneous seizures have shown that neural assemblies activated prior to the start of seizures were reactivated during post-seizure sleep, similar to the reactivation of behavioral neural assemblies, which is thought to be involved in the formation of long-term memories, a process known as Memory Consolidation. The reactivation of seizure-related neural assemblies during sleep was thus described as being a component of Seizure-Related Consolidation (SRC). These results further suggest that SRC may viewed as a network-related aspect of epilepsy, even in those seizures that have anatomically restricted neuroanatomical origins. As suggested by the Network Theory of Epilepsy as a means of interfering with ictogenesis, therapies that interfered with SRC may provide some anti-epileptogenic therapeutic benefit, even if the interference targeted structures that were not involved originally in the seizure. Here, we show how the Network Theory of Epilepsy can be expanded to include neural plasticity mechanisms associated with learning by providing an overview of Memory Consolidation, the mechanisms thought to underlie MC, their relation to Seizure-Related Consolidation, and suggesting novel, anti-epileptogenic therapies targeting interference with network activation in epilepsy following seizures during post-seizure sleep.

Sleep, Nutrition, and Health Maintenance in Cardiothoracic Surgery

Cardiothoracic surgeons work in high-intensity environments starting in surgical training and throughout their careers. They deal with critical patients. Their routine procedures are delicate, require extensive attention to detail, and can have detrimental effects on patients' lives. Cardiothoracic surgeons are required to perform at their best capacity incessantly. To do this, they must safeguard their mental and physical well-being. Preserving health through sleep, nutrition, exercise, and routine medical checkups ensures a cardiothoracic surgeon's well-being. Great personal effort and discipline is required to maintain health in a busy schedule. We offer our best recommendations from expert peers in the field.

Synapses tagged, memories kept: synaptic tagging and capture hypothesis in brain health and disease

The synaptic tagging and capture (STC) hypothesis lays the framework on the synapse-specific mechanism of protein synthesis-dependent long-term plasticity upon synaptic induction. Activated synapses will display a transient tag that will capture plasticity-related products (PRPs). These two events, tag setting and PRP synthesis, can be teased apart and have been studied extensively-from their electrophysiological and pharmacological properties to the molecular events involved. Consequently, the hypothesis also permits interactions of synaptic populations that encode different memories within the same neuronal population-hence, it gives rise to the associativity of plasticity. In this review, the recent advances and progress since the experimental debut of the STC hypothesis will be shared. This includes the role of neuromodulation in PRP synthesis and tag integrity, behavioural correlates of the hypothesis and modelling in silico. STC, as a more sensitive assay for synaptic health, can also assess neuronal aberrations. We will also expound how synaptic plasticity and associativity are altered in ageing-related decline and pathological conditions such as juvenile stress, cancer, sleep deprivation and Alzheimer's disease. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.

Sleep induced by mechanosensory stimulation provides cognitive and health benefits in Drosophila

Study Objectives

Sleep is a complex phenomenon regulated by various factors, including sensory input. Anecdotal observations have suggested that gentle rocking helps babies fall asleep, and experimental studies have verified that rocking promotes sleep in both humans and mice. Recent studies have expanded this understanding, demonstrating that gentle vibration also induces sleep in Drosophila. Natural sleep serves multiple functions, including learning and memory, synaptic downscaling, and clearance of harmful substances associated with neurodegenerative diseases. Here, we investigated whether vibration-induced sleep provides similar cognitive and health benefits in Drosophila.

Methods

We administered gentle vibration to flies that slept very little due to a forced activation of wake-promoting neurons and investigated how the vibration influenced learning and memory in the courtship conditioning paradigm. Additionally, we examined the effects of VIS on synaptic downscaling by counting synapse numbers of select neurons. Finally, we determined whether vibration could induce sleep in Drosophila models of Alzheimer's disease (AD) and promote the clearance of Amyloid b (Ab) and Tubulin Associated Unit (TAU).

Results

Vibration-induced sleep enhanced performance in a courtship conditioning paradigm and reduced the number of synapses in select neurons. Moreover, vibration improved sleep in Drosophila models of AD, promoting the clearance of Ab and TAU.

Conclusions

Mechanosensory stimulation offers a promising non-invasive avenue for enhancing sleep, potentially providing associated cognitive and health benefits.

Get out of my head: social evaluative brain states carry over into post-feedback rest and influence remembering how others view us

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.

The role of objective sleep in implicit and explicit affect regulation: A comprehensive review

Impairments in sleep and affect regulation are evident across a wide range of mental disorders. Understanding the sleep factors that relate to affect regulatory difficulties will inform mechanistic understanding and aid in treatment. Despite rising interest, some research challenges in this area include integrating across different clinical and non-clinical literatures investigating the role of sleep architecture (measured with polysomnography) and experimentally manipulated sleep, as well as integrating more explicit versus implicit affect regulation processes. In this comprehensive review, we use a unifying framework to examine sleep's relationship with implicit-automatic regulation and explicit-controlled regulation, both of which are relevant to mental health (e.g., PTSD and depression). Many studies of implicit-automatic regulation (e.g., fear extinction and safety learning) demonstrate the importance of sleep, and REM sleep specifically. Studies of explicit-controlled regulation (e.g., cognitive reappraisal and expressive suppression) are less consistent in their findings, with results differing depending on the type of affect regulation and/or way that sleep was measured or manipulated. There is a clear relationship between objective sleep and affect regulation processes. However, there is a need for 1) more studies focusing on sleep and explicit-controlled affect regulation; 2) replication with the same types of regulation strategies; 3) more studies experimentally manipulating sleep to examine its impact on affect regulation and vice versa in order to infer cause and effect; and 4) more studies looking at sleep's impact on next-day affect regulation (not just overnight change in affect reactivity).

Study Protocol: Global Research Initiative on the Neurophysiology of Schizophrenia (GRINS) project

BACKGROUND

Objective and quantifiable markers are crucial for developing novel therapeutics for mental disorders by 1) stratifying clinically similar patients with different underlying neurobiological deficits and 2) objectively tracking disease trajectory and treatment response. Schizophrenia is often confounded with other psychiatric disorders, especially bipolar disorder, if based on cross-sectional symptoms. Awake and sleep EEG have shown promise in identifying neurophysiological differences as biomarkers for schizophrenia. However, most previous studies, while useful, were conducted in European and American populations, had small sample sizes, and utilized varying analytic methods, limiting comprehensive analyses or generalizability to diverse human populations. Furthermore, the extent to which wake and sleep neurophysiology metrics correlate with each other and with symptom severity or cognitive impairment remains unresolved. Moreover, how these neurophysiological markers compare across psychiatric conditions is not well characterized. The utility of biomarkers in clinical trials and practice would be significantly advanced by well-powered transdiagnostic studies. The Global Research Initiative on the Neurophysiology of Schizophrenia (GRINS) project aims to address these questions through a large, multi-center cohort study involving East Asian populations. To promote transparency and reproducibility, we describe the protocol for the GRINS project.

METHODS

The research procedure consists of an initial screening interview followed by three subsequent sessions: an introductory interview, an evaluation visit, and an overnight neurophysiological recording session. Data from multiple domains, including demographic and clinical characteristics, behavioral performance (cognitive tasks, motor sequence tasks), and neurophysiological metrics (both awake and sleep electroencephalography), are collected by research groups specialized in each domain.

CONCLUSION

Pilot results from the GRINS project demonstrate the feasibility of this study protocol and highlight the importance of such research, as well as its potential to study a broader range of patients with psychiatric conditions. Through GRINS, we are generating a valuable dataset across multiple domains to identify neurophysiological markers of schizophrenia individually and in combination. By applying this protocol to related mental disorders often confounded with each other, we can gather information that offers insight into the neurophysiological characteristics and underlying mechanisms of these severe conditions, informing objective diagnosis, stratification for clinical research, and ultimately, the development of better-targeted treatment matching in the clinic.

A 108-h total sleep deprivation did not impair fur seal performance in delayed matching to sample task

While the majority of studies have concluded that sleep deprivation causes detrimental effects on various cognitive processes, some studies reported conflicting results. We examined the effects of a 108-h total sleep deprivation (TSD) on working memory in the northern fur seal, an animal with unusual sleep phenomenology and long-range annual migrations. The performance of fur seals was evaluated in a two-choice visual delayed matching to sample (DMTS) task, which is commonly used to evaluate working memory. In baseline conditions, the performance of fur seals in a DMTS task based on the percentage of errors was somewhat comparable with that in nonhuman primates at similar delays. We have determined that a 108-h TSD did not affect fur seals' performance in a visual DMTS task as measured by overall percentage of errors and response latencies. On the contrary, all fur seals improved task performance over the study, including the baseline, TSD and recovery conditions. In addition, TSD did not change the direction and strength of the pattern of behavioral lateralization in fur seals. We conclude that a 108-h TSD did not interfere with working memory in a DMTS test in northern fur seals.

Guhan Yangsheng Jing mitigates hippocampal neuronal pyroptotic injury and manifies learning and memory capabilities in sleep deprived mice via the NLRP3/Caspase1/GSDMD signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Guhan Yangsheng Jing (GHYSJ) is a traditional Chinese patent medicine, that has the function of nourishing the kidney and replenishing the essence, invigorating the brain and calming the mind. It is often used to treat dizziness, memory loss, sleep disorders, fatigue, and weakness, etc. However, its mechanism for improving sleep has not yet been determined.

AIM OF THE STUDY

This study aims to explore the effects of GHYSJ on Sleep Deprivation (SD)-induced hippocampal neuronal pyroptotic injury, learning and cognitive abilities, and sleep quality in mice.

METHODS

In this study, a PCPA-induced SD mouse model was established. We assessed the influence of GHYSJ on sleep quality and mood by using the pentobarbital-induced sleep test (PIST) and sucrose preference test (SPT). The pharmacological effects of GHYSJ on learning and memory impairment were evaluated by the Morris Water Maze (MWM) and Open Field Test (OFT). Pathological changes in the hippocampal tissue of the SD rats were observed via HE staining and Nissl staining. The severity of neuronal damage was evaluated by detecting the expression of the neuronal marker Microtubule-associated protein 2 (MAP2), via immunohistochemistry and immunofluorescence. Furthermore, the levels of neurotransmitter 5-hydroxytryptophan (5-HTP), 5-hydroxy tryptamine (5-HT), γ-aminobutyric acid (GABA), and Glutamic acid (Glu) in hippocampal tissues, as well as the expression of inflammatory factors Interleukin-1β (IL-1β) and Interleukin-18 (IL-18) in serum, were determined by ELISA. The expressions of mRNA and protein NOD-like receptor thermal protein domain associated protein 3 (NLRP3), Gasdermin D (GSDMD), Cysteinyl aspartate specific proteinase1 (Caspase1), High mobility group box-1 protein (HMGB1) and Apoptosis-associated speck-like protein containing CARD (ASC) related to the cellular ferroptosis pathway were tested and analyzed by RT-PCR and WB respectively.

RESULTS

PCPA significantly diminishes the sleep span of experimental animals by expediting the expenditure of 5-HT, consequently establishing an essentially direct SD model. The intervention of GHYSJ displays remarkable efficacy in mitigating insomnia symptoms, encompassing difficulties in initiating sleep and insufficient sleep duration. Likewise, it ameliorates memory function impairments induced by sleep deprivation, along with symptoms such as fatigue and depletion of vitality. GHYSJ exerts a protective influence on hippocampal neurons facilitated by inhibiting the down regulation of MAP2 and maintaining the equilibrium of neurotransmitters (5-HTP, 5-HT, GABA, and Glu). It diminishes the expression of intracellular pyroptosis-associated inflammatory factors (IL-1β and IL-18) and curbs the activation of the NLRP3/Caspase1/GSDMD pyroptosis-related signaling pathways, thereby alleviating the damage caused by hippocampal neuronal pyroptosis.

Parental and Child Sleep: Children with Vision Impairment, Autistic Children, and Children with Comorbid Vision Impairment and Autism

BACKGROUND

Parents report associations between children's sleep disturbances and behaviors. Children with neurodevelopmental conditions (e.g., Williams Syndrome and autism) are consistently reported to experience increased sleeping problems. Sleep in children with vision impairment and children with a dual diagnosis of vision impairment and autism remains understudied.

METHODS

Our exploratory study compared sleep profiles in 52 children (aged 4-12 years) and their parents (n = 37), across four groups: children with vision impairment (VI; n = 9), autism (n = 10), comorbid vision impairment + autism (n = 6), and typically developing children (n = 27). Childhood sleep was measured using the parental report Childhood Sleep Habits Questionnaire and sleep diaries. Children's cognitive functioning was measured using digit span, semantic, and phonemic verbal fluency measures. Parental sleep was measured via the Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale.

RESULTS

Clinically disordered sleep was reported in all child groups (p ≤ 0.001), particularly children with VI + autism. Age, not sleep quality/quantity, predicted cognitive task performance in TD and autistic groups, but not in VI and VI + autism groups. The child's diagnosis affected parental sleep, particularly in children with a dual diagnosis of VI + autism.

CONCLUSIONS

All participants experienced problematic sleep to varying degrees. Those most affected were children and parents in the VI + autism group, suggesting that autism may be the main driver of sleep problems in our sample.

The dorsomedial prefrontal cortex prioritizes social learning during rest

Sociality is a defining feature of the human experience: We rely on others to ensure survival and cooperate in complex social networks to thrive. Are there brain mechanisms that help ensure we quickly learn about our social world to optimally navigate it? We tested whether portions of the brain's default network engage "by default" to quickly prioritize social learning during the memory consolidation process. To test this possibility, participants underwent functional MRI (fMRI) while viewing scenes from the documentary film, Samsara. This film shows footage of real people and places from around the world. We normed the footage to select scenes that differed along the dimension of sociality, while matched on valence, arousal, interestingness, and familiarity. During fMRI, participants watched the "social" and "nonsocial" scenes, completed a rest scan, and a surprise recognition memory test. Participants showed superior social (vs. nonsocial) memory performance, and the social memory advantage was associated with neural pattern reinstatement during rest in the dorsomedial prefrontal cortex (DMPFC), a key node of the default network. Moreover, it was during early rest that DMPFC social pattern reinstatement was greatest and predicted subsequent social memory performance most strongly, consistent with the "prioritization" account. Results simultaneously update 1) theories of memory consolidation, which have not addressed how social information may be prioritized in the learning process, and 2) understanding of default network function, which remains to be fully characterized. More broadly, the results underscore the inherent human drive to understand our vastly social world.

Multivariate classification of multichannel long-term electrophysiology data identifies different sleep stages in fruit flies

Identifying different sleep stages in humans and other mammals has traditionally relied on electroencephalograms. Such an approach is not feasible in certain animals such as invertebrates, although these animals could also be sleeping in stages. Here, we perform long-term multichannel local field potential recordings in the brains of behaving flies undergoing spontaneous sleep bouts. We acquired consistent spatial recordings of local field potentials across multiple flies, allowing us to compare brain activity across awake and sleep periods. Using machine learning, we uncover distinct temporal stages of sleep and explore the associated spatial and spectral features across the fly brain. Further, we analyze the electrophysiological correlates of microbehaviors associated with certain sleep stages. We confirm the existence of a distinct sleep stage associated with rhythmic proboscis extensions and show that spectral features of this sleep-related behavior differ significantly from those associated with the same behavior during wakefulness, indicating a dissociation between behavior and the brain states wherein these behaviors reside.

Sequence-specific delayed gains in motor fluency evolve after movement observation training in the absence of early sleep

Following physical practice, delayed, consolidation-phase, gains in the performance of the trained finger-to-thumb opposition sequence (FOS) can be expressed, in young adults, only after a sleep interval is afforded. These delayed gains are order-of-movements specific. However, in several perceptual learning tasks, time post-learning, rather than an interval of sleep, may suffice for the expression of delayed performance gains. Here we tested whether the affordance of a sleep interval is necessary for the expression of delayed performance gains after FOS training by repeated observation. Participants were trained by observing videos displaying a left hand repeatedly performing a 5-element FOS. To assess post-session observation-related learning and delayed gains participants were tested in performing the observed (trained) and an unobserved (new, the 5-elements mirror-reversed) FOS sequences. Repeated observation of a FOS conferred no advantage to its performance, compared to the unobserved FOS, immediately after practice. However, a clear advantage for the observed FOS emerged by 12 h post-training, irrespective of whether this interval included sleep or not; the largest gains appeared by 24 h post-training. These results indicate that time-dependent, offline consolidation processes take place after observation training even in the absence of sleep; akin to perceptual learning rather than physical FOS practice.

Procedural Motor Memory Deficits in Patients With Long-COVID

BACKGROUND AND OBJECTIVES

At least 15% of patients who recover from acute severe acute respiratory syndrome coronavirus 2 infection experience lasting symptoms ("Long-COVID") including "brain fog" and deficits in declarative memory. It is not known if Long-COVID affects patients' ability to form and retain procedural motor skill memories. The objective was to determine the ability of patients with Long-COVID to acquire and consolidate a new procedural motor skill over 2 training days. The primary outcome was to determine difference in early learning, measured as the increase in correct sequence typing speed over the initial 11 practice trials of a new skill. The secondary outcomes were initial and final typing speed on days 1 and 2, learning rate, overnight consolidation, and typing accuracy.

METHODS

In this prospective, cross-sectional, online, case-control study, participants learned a sequential motor skill over 2 consecutive days (NCT05746624). Patients with Long-COVID (reporting persistent post-coronavirus disease 2019 [COVID-19] symptoms for more than 4 weeks) were recruited at the NIH. Patients were matched one-to-one by age and sex to controls recruited during the pandemic using a crowd-sourcing platform. Selection criteria included age 18-90 years, English speaking, right-handed, able to type with the left hand, denied active fever or respiratory infection, and no previous task exposure. Data were also compared with an age-matched and sex-matched control group who performed the task online before the COVID-19 pandemic (prepandemic controls).

RESULTS

In total, 105 of 236 patients contacted agreed to participate and completed the experiment (mean ± SD age 46 ± 12.8 years, 82% female). Both healthy control groups had 105 participants (mean age 46 ± 13.1 and 46 ± 11.9 years, 82% female). Early learning was comparable across groups (Long-COVID: 0.36 ± 0.24 correct sequences/second, pandemic controls: 0.36 ± 0.53 prepandemic controls: 0.38 ± 0.57, patients vs pandemic controls [CI -0.068 to 0.067], vs prepandemic controls [CI -0.084 to 0.052], and between controls [CI -0.083 to 0.053], p = 0.82). Initial and final typing speeds on days 1 and 2 were slower in patients than controls. Patients with Long-COVID showed a significantly reduced overnight consolidation and a nonsignificant trend to reduced learning rates.

DISCUSSION

Early learning was comparable in patients with Long-COVID and controls. Anomalous initial performance is consistent with executive dysfunction. Reduction in overnight consolidation may relate to deficits in procedural memory formation.

Parallel cognitive maps for multiple knowledge structures in the hippocampal formation

The hippocampal-entorhinal system uses cognitive maps to represent spatial knowledge and other types of relational information. However, objects can often be characterized by different types of relations simultaneously. How does the hippocampal formation handle the embedding of stimuli in multiple relational structures that differ vastly in their mode and timescale of acquisition? Does the hippocampal formation integrate different stimulus dimensions into one conjunctive map or is each dimension represented in a parallel map? Here, we reanalyzed human functional magnetic resonance imaging data from Garvert et al. (2017) that had previously revealed a map in the hippocampal formation coding for a newly learnt transition structure. Using functional magnetic resonance imaging adaptation analysis, we found that the degree of representational similarity in the bilateral hippocampus also decreased as a function of the semantic distance between presented objects. Importantly, while both map-like structures localized to the hippocampal formation, the semantic map was located in more posterior regions of the hippocampal formation than the transition structure and thus anatomically distinct. This finding supports the idea that the hippocampal-entorhinal system forms parallel cognitive maps that reflect the embedding of objects in diverse relational structures.

Neuromodulation via muscarinic acetylcholine pathway can facilitate distinct, complementary, and sequential roles for NREM and REM states during sleep-dependent memory consolidation

Across vertebrate species, sleep consists of repeating cycles of NREM followed by REM. However, the respective functions of NREM, REM, and their stereotypic cycling pattern are not well understood. Using a simplified biophysical network model, we show that NREM and REM sleep can play differential and critical roles in memory consolidation primarily regulated, based on state-specific changes in cholinergic signaling. Within this network, decreasing and increasing muscarinic acetylcholine (ACh) signaling during bouts of NREM and REM, respectively, differentially alters neuronal excitability and excitatory/inhibitory balance. During NREM, deactivation of inhibitory neurons leads to network-wide disinhibition and bursts of synchronized activity led by firing in engram neurons. These features strengthen connections from the original engram neurons to less-active network neurons. In contrast, during REM, an increase in network inhibition suppresses firing in all but the most-active excitatory neurons, leading to competitive strengthening/pruning of the memory trace. We tested the predictions of the model against in vivo recordings from mouse hippocampus during active sleep-dependent memory storage. Consistent with modeling results, we find that functional connectivity between CA1 neurons changes differentially at transition from NREM to REM sleep during learning. Returning to the model, we find that an iterative sequence of state-specific activations during NREM/REM cycling is essential for memory storage in the network, serving a critical role during simultaneous consolidation of multiple memories. Together these results provide a testable mechanistic hypothesis for the respective roles of NREM and REM sleep, and their universal relative timing, in memory consolidation.

Significance statement

Using a simplified computational model and in vivo recordings from mouse hippocampus, we show that NREM and REM sleep can play differential roles in memory consolidation. The specific neurophysiological features of the two sleep states allow for expansion of memory traces (during NREM) and prevention of overlap between different memory traces (during REM). These features are likely essential in the context of storing more than one new memory simultaneously within a brain network.

A Matter of Time: A Web-Based Investigation of Rest and Sleep Effects on Speech Motor Learning

PURPOSE

Here, we examine the possibility that memory consolidation during a period of postpractice rest or nocturnal sleep can bolster speech motor learning in the absence of additional practice or effort.

METHOD

Using web-administered experiments, 74 typical, American English talkers trained in a nonnative vowel contrast then had a 12-hr delay with (SLEEP) or without nocturnal sleep (REST) or proceeded immediately (IMMEDIATE) to a posttraining production assessment. For ecological validity, 51 native Danish talkers perceptually identified the American English talkers' productions.

RESULTS

We observed that practice resulted in productions that were more acoustically similar to the Danish target. In addition, we found that rest in the absence of further practice reduced the token-to-token variability of the productions. Last, for vowels produced immediately following training, listeners more accurately identified vowels in the trained context, whereas in the untrained context, listener accuracy improved only for vowels produced by talkers who slept.

CONCLUSIONS

A single session of speech motor training promotes observable change to speech production behavior. Specifically, practice facilitates acoustic similarity to the target. Moreover, although a 12-hr postpractice period of rest appears to promote productions that are less variable, only the productions of those who slept are perceived as more accurate by listeners. This may point to sleep's role in contextualizing the acoustic goal of the production to the learner's own vocal tract and its role as a protective mechanism during learning. These results are unaccounted for under existing models and offer potential for future educational and clinical applications to maximize speech motor learning.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24707442.

Development of the sleep-wake switch in rats during the P2-P21 early infancy period

In early infancy, rats randomly alternate between the sleeping and waking states-from postnatal day 2-10 (P2-P10), sleep and wake bouts are both exponentially distributed with increasing means, while from P10-P21 sleep and wake bout means continue to increase, though there is a striking qualitative shift in the distribution of wake bouts from exponential to power law. The behavioral states of sleep and wakefulness correspond to the activity of sleep-active and wake-active neuronal brainstem populations, with reciprocal inhibition between the two ensuring that only one population is active at a time. The locus coeruleus (LC) forms a third component of this circuit that rises in prominence during the P10-P21 period, as experimental evidence shows that an as-of-yet undeciphered interaction of the LC with sleep-active and wake-active populations is responsible for the transformation of the wake bout distribution from exponential to power law. Interestingly, the LC undergoes remarkable physiological changes during the P10-P21 period-gap junctions within the LC are pruned and network-wide oscillatory synchrony declines and vanishes. In this work, we discuss a series of models of sleep-active, wake-active, and the LC populations, and we use these models to postulate the nature of the interaction between these three populations and how these interactions explain empirical observations of sleep and wake bout dynamics. We hypothesize a circuit in which there is reciprocal excitation between the LC and wake-active population with inhibition from the sleep-active population to the LC that suppresses the LC during sleep bouts. During the P2-P10 period, we argue that a noise-based switching mechanism between the sleep-active and wake-active populations provides a simple and natural way to account for exponential bout distributions, and that the locked oscillatory state of the LC prevents it from impacting bout distributions. From P10-P21, we use our models to postulate that, as the LC gradually shifts from a state of synchronized oscillations to a state of continuous firing, reciprocal excitation between the LC and the wake-active population is able to gradually transform the wake bout distribution from exponential to power law.

Sleep in the Athlete

Sleep is important for not only general health but also for lowering injury risk and maintaining athletic performance. Sleep disorders are prevalent in athletes, and taking a sleep history, evaluating sleep quality, and addressing other related factors including mental health are essential in diagnosing and understanding sleep disorders. Other methods such as polysomnography, actigraphy, and sheet sensors can also be used. Treatment options for sleep disorders include sleep hygiene, cognitive behavioral therapy, medication, and addressing contributing factors. For athletes, sleep can also be affected by factors such as travel fatigue and jet lag, which should be taken into consideration.

Epilepsy Surgery for Cognitive Improvement in Epileptic Encephalopathy

Epileptic encephalopathies are defined by the presence of frequent epileptiform activity that causes neurodevelopmental slowing or regression. Here, we review evidence that epilepsy surgery improves neurodevelopment in children with epileptic encephalopathies. We describe an example patient with epileptic encephalopathy without drug refractory seizures, who underwent successful diagnostic and therapeutic surgeries. In patients with epileptic encephalopathy, cognitive improvement alone is a sufficient indication to recommend surgical intervention in experienced centers.

Efficient, continual, and generalized learning in the brain - neural mechanism of Mental Schema 2.0

There has been tremendous progress in artificial neural networks (ANNs) over the past decade; however, the gap between ANNs and the biological brain as a learning device remains large. With the goal of closing this gap, this paper reviews learning mechanisms in the brain by focusing on three important issues in ANN research: efficiency, continuity, and generalization. We first discuss the method by which the brain utilizes a variety of self-organizing mechanisms to maximize learning efficiency, with a focus on the role of spontaneous activity of the brain in shaping synaptic connections to facilitate spatiotemporal learning and numerical processing. Then, we examined the neuronal mechanisms that enable lifelong continual learning, with a focus on memory replay during sleep and its implementation in brain-inspired ANNs. Finally, we explored the method by which the brain generalizes learned knowledge in new situations, particularly from the mathematical generalization perspective of topology. Besides a systematic comparison in learning mechanisms between the brain and ANNs, we propose "Mental Schema 2.0," a new computational property underlying the brain's unique learning ability that can be implemented in ANNs.