Sleep smart-optimizing sleep for declarative learning and memory

Long-term memory consolidation of new words in children with self-limited epilepsy with centro-temporal spikes

Accelerated long-term forgetting has been studied and demonstrated in adults with epilepsy. In contrast, the question of long-term consolidation (delays > 1 day) in children with epilepsy shows conflicting results. However, childhood is a period of life in which the encoding and long-term storage of new words is essential for the development of knowledge and learning. The aim of this study was therefore to investigate long-term memory consolidation skills in children with self-limited epilepsy with centro-temporal spikes (SeLECTS), using a paradigm exploring new words encoding skills and their long-term consolidation over one-week delay. As lexical knowledge, working memory skills and executive/attentional skills has been shown to contribute to long-term memory/new word learning, we added standardized measures of oral language and executive/attentional functions to explore the involvement of these cognitive skills in new word encoding and consolidation. The results showed that children with SeLECTS needed more repetitions to encode new words, struggled to encode the phonological forms of words, and when they finally reached the level of the typically developing children, they retained what they had learned, but didn't show improved recall skills after a one-week delay, unlike the control participants. Lexical knowledge, verbal working memory skills and phonological skills contributed to encoding and/or recall abilities, and interference sensitivity appeared to be associated with the number of phonological errors during the pseudoword encoding phase. These results are consistent with the functional model linking working memory, phonology and vocabulary in a fronto-temporo-parietal network. As SeLECTS involves perisylvian dysfunction, the associations between impaired sequence storage (phonological working memory), phonological representation storage and new word learning are not surprising. This dual impairment in both encoding and long-term consolidation may result in large learning gap between children with and without epilepsy. Whether these results indicate differences in the sleep-induced benefits required for long-term consolidation or differences in the benefits of retrieval practice between the epilepsy group and healthy children remains open. As lexical development is associated with academic achievement and comprehension, the impact of such deficits in learning new words is certainly detrimental.

Sleep duration trajectories and cognition in early childhood: A systematic review

Sleep is dynamic in childhood and studies have shown the relationship between sleep and cognition in children. As the human brain is the most plastic during childhood, the study of longitudinal sleep patterns and neurocognition is an important research area. We aimed to systematically review studies that investigated sleep duration trajectories and cognition in typically-developing children. We searched four databases for articles published between 2003 to October 2023. We included observation studies of children with sleep duration trajectories as a predictor and outcomes related to cognition, memory, language, developmental milestones, intelligence or executive function. We excluded studies where children had atypical development or completed the sleep and neurocognitive assessments after six and 12 years of age respectively. Out of 752 articles identified, 511 were screened and 23 full texts were assessed. The selected studies included three single trajectory and four multiple group trajectories studies. We found associations between both types of trajectories and cognitive development. Overall, children with longer sleep trajectories or more mature sleep pattern with rapid decrease in sleep duration, had better performance scores in developmental assessment tools, and intelligence tests. Findings for language and executive functioning were mixed, whereby some studies found associations and others did not.

Sex Differences in Sleep Architecture After Traumatic Brain Injury: Potential Implications on Short-Term Episodic Memory and Recovery

Sleep-wake disturbances (SWDs) are common after TBI and often extend into the chronic phase of recovery. Such disturbances in sleep can lead to deficits in executive functioning, attention, and memory consolidation, which may ultimately impact the recovery process. We examined whether SWDs post-TBI were associated with morbidity during the post-acute period. Particular attention was placed on the impact of sleep architecture on learning and memory. Because women are more likely to report SWDs, we examined sex as a biological variable. We also examined subjective quality of life, depression, and disability levels. Data were retrospectively analyzed for 57 TBI patients who underwent an overnight polysomnography. Medical records were reviewed to determine cognitive and functional status during the period of the sleep evaluation. Consideration was given to medications, owing to the fact that a high number of these are likely to have secondary influences on sleep characteristics. Women showed higher levels of disability and reported more depression and lower quality of life. A sex-dependent disruption in sleep architecture was observed, with women having lower percent time in REM sleep. An association between percent time in REM and better episodic memory scores was found. Melatonin utilization had a positive impact on REM duration. Improvements in understanding the impact of sleep-wake disturbances on post-TBI outcome will aid in defining targeted interventions for this population. Findings from this study support the hypothesis that decreases in REM sleep may contribute to chronic disability and underlie the importance of considering sex differences when addressing sleep.

Respiration modulates sleep oscillations and memory reactivation in humans

The beneficial effect of sleep on memory consolidation relies on the precise interplay of slow oscillations and spindles. However, whether these rhythms are orchestrated by an underlying pacemaker has remained elusive. Here, we tested the relationship between respiration, which has been shown to impact brain rhythms and cognition during wake, sleep-related oscillations and memory reactivation in humans. We re-analysed an existing dataset, where scalp electroencephalography and respiration were recorded throughout an experiment in which participants (N = 20) acquired associative memories before taking a nap. Our results reveal that respiration modulates the emergence of sleep oscillations. Specifically, slow oscillations, spindles as well as their interplay (i.e., slow-oscillation_spindle complexes) systematically increase towards inhalation peaks. Moreover, the strength of respiration - slow-oscillation_spindle coupling is linked to the extent of memory reactivation (i.e., classifier evidence in favour of the previously learned stimulus category) during slow-oscillation_spindles. Our results identify a clear association between respiration and memory consolidation in humans and highlight the role of brain-body interactions during sleep.

Illustrations of interactions needed when investigating sleep using a type of AM-PM PM-AM design

Sleep has long been thought of and promoted to be beneficial for memory. Some claims that sleep aids memory have been made in the absence of a critical interaction. This condition is necessary when using a commonly-used experimental design (a type of AM-PM PM-AM design). We propose that a sleep effect exists only if there is an interaction between groups (experimental and time-of-day controls) and the time of test or study (morning and evening). We show different patterns of results that would and would not support a sleep effect with empirical and model-generated data from recognition memory experiments and hypothetical data. While we use these data to make our point, our suggestions apply to any memory and non-memory-related investigation (e.g., emotional memory, false memory susceptibility, language learning, problem-solving). Testing for and finding the proper interaction will add to the evidence that sleep boosts performance.

Sleep disturbances in specific learning disorders: a qualitative and quantitative investigation

BACKGROUND

The literature reports a significant association between sleep disorders and learning disabilities. Nevertheless, not all children with learning disorders have sleep alterations, and which sleep characteristics are associated with which learning difficulty is still unknown. The study aimed at acquiring new information on the relation between sleep disturbances or habits and the learning profiles of children with a specific learning disorder (SLD).

METHODS

The Sleep Disturbance Scale for Children (SDSC) and an actigraph (the FitBit-Flex, FB-F) were used in 26 and 16 SLD children respectively; all children were also assessed for learning skills.

RESULTS

Although parents' reports at the SDSC did not differentiate SLD from typical readers, the awakening, respiratory and arousal disturbances at the SDSC correlated with sleep duration at the FB-F. Sleep alterations at the FB-F actigraph characterize SLD with literacy difficulties: children with reading decoding difficulties showed shorter minimum amount of sleep than typical children, and severe SLDs showed shorter maximum sleep duration and a higher number of awakenings in comparison to SLDs with mild learning deficits.

CONCLUSIONS

Mild alterations in the amount, duration and quality of sleep may characterize children with learning disorders and actigraphy proves to be a useful tool in starting the individual monitoring of sleep in these populations.

One-week sleep hygiene education improves episodic memory in young but not in older adults during social isolation

Memory formation is a dynamic process that comprises different phases, such as encoding, consolidation and retrieval. It could be altered by several factors such as sleep quality, anxiety, and depression levels. In the last years, due to COVID-19 pandemic, there was a reduction in sleep quality, an increase in anxiety and depressive symptoms as well as an impairment in emotional episodic memory encoding, especially in young adults. Taking into account the profound impact of sleep quality in daily life a series of rules has been developed that are conducive to consistently achieving good sleep, known as sleep hygiene education. These interventions have been shown to be effective in improving sleep quality and duration and reducing depressive and anxiety symptoms. Here we propose the implementation of a brief sleep hygiene education to improve sleep quality and memory performance as well as to diminish anxiety and depressive scores. For that, participants were divided into two groups: Sleep hygiene education and control group. After that, they were evaluated for anxiety, depression, and sleep quality levels and trained on an episodic memory task. They were tested immediately after (short-term test) and also 1 week later (long-term test). This procedure was also performed before the sleep hygiene education and was taken as baseline level. We found that episodic memory performance for young adults improved for the SHE group after intervention but not for older adults, and no improvements in emotional variables were observed. Despite not observing a significant effect of the intervention for young and older adults regarding the sleep quality scores, we consider that there may be an improvement in sleep physiology that is not subjectively perceived, but would also have a positive impact on memory processes. These results show that even a sleep hygiene education of 1 week could improve cognition in young adults when acute memory and sleep impairment occurs, in this case, due to the isolation by COVID-19 pandemic. However, we suggest that longer interventions should be implemented for older adults who already experience a natural decline in cognitive processes such as episodic memory formation.

Learning to Learn: A pilot study on explicit strategy instruction to incoming college students

The current pilot study implemented a "Learning to Learn" (L2L) course designed to teach first-year college students about the science of how learning works, how to take ownership of their own learning, and how to effectively apply learning strategies to achieve their academic goals. A cognitive apprenticeship model was used in which students planned, executed, and evaluated strategy use in vivo during the course. Two sections of the course were taught at each of two different institutions, distributed across four semesters. Quantitative data showed an increased growth mindset among L2L students at the end of the semester compared to the beginning of the semester. In contrast, first-year students surveyed from control groups in the same semester had a decreased growth mindset. Furthermore, compared to students in the control groups, students in the L2L courses maintained more stable levels of effort across the semester and felt more in control of their learning by the end of the semester. Qualitative data collected from focus groups indicated that the L2L students continued to use the strategies they had learned in the course in the subsequent semester, and that the changes in their perceptions about growth mindset continued beyond the duration of the course. Several L2L students noted a desire for the learning strategies to be taught earlier in their education. Next steps involve feasibility studies on appropriate scaling to support more undergraduates each year, and to support students during the critical transition from K-12 schooling to the college environment.

No evidence for a preferential role of sleep in episodic memory abstraction

Substantial evidence suggests that sleep has a role in declarative memory consolidation. An influential notion holds that such sleep-related memory consolidation is associated with a process of abstraction. The neural underpinnings of this putative process are thought to involve a hippocampo-neocortical dialogue. Specifically, the idea is that, during sleep, the statistical contingencies across episodes are re-coded to a less hippocampus-dependent format, while at the same time losing configural information. Two previous studies from our lab, however, failed to show a preferential role of sleep in either episodic memory decontextualisation or the formation of abstract knowledge across episodic exemplars. Rather these processes occurred over sleep and wake time alike. Here, we present two experiments that replicate and extend these previous studies and exclude some alternative interpretations. The combined data show that sleep has no preferential function in this respect. Rather, hippocampus-dependent memories are generalised to an equal extent across both wake and sleep time. The one point on which sleep outperforms wake is actually the preservation of episodic detail of memories stored prior to sleep.

Advances in the understanding and enhancement of the human cognitive functions of learning and memory

Learning and memory are among the key cognitive functions that drive the human experience. As such, any defective condition associated with these cognitive domains could affect our navigation through everyday life. For years, researchers have been working toward having a clear understanding of how learning and memory work, as well as ways to improve them. Many advances have been made, as well as some challenges that have also been faced in the process. That notwithstanding, there are prospects with regards to the frontier of the enhancement of learning and memory in humans. This review article selectively highlights four broad areas of focus in research into the understanding and enhancement of learning and memory. Brain stimulation, effects of sleep, effects of stress and emotion, and synaptic plasticity are the main focal areas of this review, in terms of some pivotal research works, findings and theories.

Pedagogical Strategies for the Enhancement of Medical Education

Clearly, memory and learning are essential to medical education. To make memory and learning more robust and long-term, educators should turn to the advances in neuroscience and cognitive science to direct their efforts. This paper describes the memory pathways and stages with emphasis leading to long-term memory storage. Particular stress is placed on this storage as a construct known as schema. Leading from this background, several pedagogical strategies are described: cognitive load, dual encoding, spiral syllabus, bridging and chunking, sleep consolidation, and retrieval practice.

Prior Exposure and Toddlers' Sleep-Related Memory for Novel Words

Children can easily link a novel word to a novel, unnamed object—something referred to as fast mapping. Despite the ease and speed with which children do this, their memories for novel fast-mapped words can be poor unless they receive memory supports such as further exposure to the words or sleep. Axelsson, Swinton, Winiger, and Horst (2018) found that 2.5-year-old children who napped after fast mapping had better retention of novel words than children who did not nap. Retention declined for those who did not nap. The children received no memory supports and determined the word-object mappings independently. Previous studies report enhanced memories after sleeping in children and adults, but the napping children’s retention in the Axelsson et al. study remained steady across time. We report a follow-up investigation where memory supports are provided after fast mapping to test whether memories would be enhanced following napping. Children’s retention of novel words improved and remained greater than chance; however, there was no nap effect with no significant difference between the children who napped and those who did not. These findings suggest that when memory supports are provided, retention improves, and the word–object mappings remain stable over time. When memory traces are weak and labile, such as after fast mapping, without further memory supports, sleeping soon after helps stabilise and prevent decay of word–object mappings.

Melatonin supplementation in the subacute phase after ischemia alleviates postischemic sleep disturbances in rats

BACKGROUND

Sleep disorders are highly prevalent among stroke survivors and impede stroke recovery. It is well established that melatonin has neuroprotective effects in animal models of ischemic stroke. However, as a modulator of endogenous physiological circadian rhythms, the effects of melatonin on poststroke sleep disorders remain unclear. In the present study, we investigated how melatonin delivered intraperitoneally once daily in the subacute phase after stroke onset, influencing neuronal survival, motor recovery, and sleep-wake profiles in rats.

METHODS

Transient ischemic stroke in male Sprague-Dawley rats was induced with 30 min occlusion of the middle cerebral artery. Melatonin or vehicle was delivered intraperitoneally once daily in the subacute phase, from 2 to 7 days after stroke. Electroencephalogram and electromyogram recordings were obtained simultaneously.

RESULTS

Compared to the effects observed in the vehicle-treated ischemic group, after 6 daily consecutive treatment of melatonin at 10 mg/kg starting at ischemic/reperfusion day 2, the infarct volume was significantly decreased (from 39.6 to 26.2%), and the degeneration of axons in the ipsilateral striatum and the contralateral corpus callosum were significantly alleviated. Sensorimotor performances were obviously improved as evidenced by significant increases in the latency to falling off the wire and in the use of the impaired forelimb. In addition to those predictable results of reducing brain tissue damage and mitigating behavioral deficits, repeated melatonin treatment during the subacute phase of stroke also alleviated sleep fragmentation through reducing sleep-wake stage transitions and stage bouts, together with increasing stage durations. Furthermore, daily administration of melatonin at 9 a.m. significantly increased the nonrapid eye movement sleep delta power during both the light and dark periods and decreased the degree of reduction of the circadian index.

CONCLUSIONS

Melatonin promptly reversed ischemia-induced sleep disturbances. The neuroprotective effects of melatonin on ischemic injury may be partially associated with its role in sleep modulation.

Specific changes in sleep oscillations after blocking human metabotropic glutamate receptor 5 in the absence of altered memory function

BACKGROUND

Sleep consolidates declarative memory by repeated replay linked to the cardinal oscillations of non-rapid eye movement (NonREM) sleep. However, there is so far little evidence of classical glutamatergic plasticity induced by this replay. Rather, we have previously reported that blocking N-methyl-D-aspartate (NMDA) or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors does not affect sleep-dependent consolidation of declarative memory.

AIMS

The aim of this study was to investigate the role of metabotropic glutamate receptor 5 (mGluR5) in memory processing during sleep.

METHODS

In two placebo-controlled within-subject crossover experiments with 20 healthy humans each, we used fenobam to block mGluR5 during sleep. In Experiment I, participants learned word-pairs (declarative task) and a finger sequence (procedural task) in the evening, then received the drug and recall was tested the next morning. To cover possible effects on synaptic renormalization processes during sleep, in Experiment II participants learned new word-pairs in the morning after sleep.

RESULTS/OUTCOMES

Surprisingly, fenobam neither reduced retention of memory across sleep nor new learning after sleep, although it severely altered sleep architecture and memory-relevant EEG oscillations. In NonREM sleep, fenobam suppressed 12-15 Hz spindles but augmented 2-4 Hz delta waves, whereas in rapid eye movement (REM) sleep it suppressed 4-8 Hz theta and 16-22 Hz beta waves. Notably, under fenobam NonREM spindles became more consistently phase-coupled to the slow oscillation.

CONCLUSIONS/INTERPRETATIONS

Our findings indicate that mGluR5-related plasticity is not essential for memory processing during sleep, even though mGlurR5 are strongly implicated in the regulation of the cardinal sleep oscillations.

Mindfulness and Other Simple Neuroscience-Based Proposals to Promote the Learning Performance and Mental Health of Students during the COVID-19 Pandemic

The COVID-19 pandemic has had a negative impact on education. The restrictions imposed have undoubtedly led to impairment of the psychological well-being of both teachers and students, and of the way they experience interpersonal relationships. As reported previously in the literature, adverse effects such as loneliness, anxiety, and stress have resulted in a decrease in the cognitive performance of school and higher education students. Therefore, the objective of this work is to present a general overview of the reported adverse effects of the COVID-19 pandemic which may potentially influence the learning performance of students. Some neuroscientific findings related to memory and cognition, such as neuroplasticity and long-term potentiation, are also shown. We also discuss the positive effects of the practice of mindfulness, as well as other simple recommendations based on neuroscientific findings such as restful sleep, physical activity, and nutrition, which can act on memory and cognition. Finally, we propose some practical recommendations on how to achieve more effective student learning in the context of the pandemic. The aim of this review is to provide some assistance in this changing and uncertain situation in which we all find ourselves, and we hope that some of the information could serve as a starting point for hypotheses to be tested in educational research and their association with neuroscience.

Slow wave activity moderates the association between new learning and traumatic brain injury severity

STUDY OBJECTIVES

Sleep-wake complaints and difficulties in making new learning are among the most persistent and challenging long-term sequelea following moderate to severe traumatic brain injury (TBI). Yet, it is unclear whether, and to what extent, sleep characteristics during the chronic stage of TBI contribute to sleep-wake and cognitive complaints. We aimed to characterize sleep architecture in chronic moderate to severe TBI adults and assess whether non-rapid eye movement slow wave activity (SWA) is associated to next day performance in episodic memory tasks according to TBI severity.

METHODS

Forty-two moderate to severe TBI participants, 12-47 months post-injury, and 38 healthy controls were tested with one night of in-laboratory polysomnography, followed the next morning by questionnaires (sleep quality, fatigue, and sleepiness) and neuropsychological assessment. We used multiple regression analyses to assess the moderator effect of SWA power on TBI severity and next-day memory performance.

RESULTS

We found that TBI participants reported worse sleep quality and fatigue, and had worse cognitive performance than controls. No between group differences were found on macro- and micro-architecture of sleep. However, SWA significantly interacted with TBI severity to explain next-day memory performance: higher SWA was more strongly associated to better memory performance in more severe TBI compared to milder TBI.

CONCLUSIONS

This study provides evidence that the injured brain is able to produce macro- and micro-architecture of sleep comparable to what is seen in healthy controls. However, with increasing TBI severity, lower non-rapid eye movement SWA power is associated with reduced ability to learn and memorise new information the following day.

Macro and micro sleep architecture and cognitive performance in older adults

We sought to determine which facets of sleep neurophysiology were most strongly linked to cognitive performance in 3,819 older adults from two independent cohorts, using whole-night electroencephalography. From over 150 objective sleep metrics, we identified 23 that predicted cognitive performance, and processing speed in particular, with effects that were broadly independent of gross changes in sleep quality and quantity. These metrics included rapid eye movement duration, features of the electroencephalography power spectra derived from multivariate analysis, and spindle and slow oscillation morphology and coupling. These metrics were further embedded within broader associative networks linking sleep with aging and cardiometabolic disease: individuals who, compared with similarly aged peers, had better cognitive performance tended to have profiles of sleep metrics more often seen in younger, healthier individuals. Taken together, our results point to multiple facets of sleep neurophysiology that track coherently with underlying, age-dependent determinants of cognitive and physical health trajectories in older adults.

Local Sleep and Alzheimer's Disease Pathophysiology

Even prior to the onset of the prodromal stages of Alzheimer's disease (AD), a constellation of sleep disturbances are apparent. A series of epidemiological studies indicate that multiple forms of these sleep disturbances are associated with increased risk for developing mild cognitive impairment (MCI) and AD, even triggering disease onset at an earlier age. Through the combination of causal manipulation studies in humans and rodents, as well as targeted examination of sleep disturbance with respect to AD biomarkers, mechanisms linking sleep disturbance to AD are beginning to emerge. In this review, we explore recent evidence linking local deficits in brain oscillatory function during sleep with local AD pathological burden and circuit-level dysfunction and degeneration. In short, three deficits in the local expression of sleep oscillations have been identified in relation to AD pathophysiology: (1) frequency-specific frontal deficits in slow wave expression during non-rapid eye movement (NREM) sleep, (2) deficits in parietal sleep spindle expression, and (3) deficits in the quality of electroencephalographic (EEG) desynchrony characteristic of REM sleep. These deficits are noteworthy since they differ from that seen in normal aging, indicating the potential presence of an abnormal aging process. How each of these are associated with β-amyloid (Aβ) and tau pathology, as well as neurodegeneration of circuits sensitive to AD pathophysiology, are examined in the present review, with a focus on the role of dysfunction within fronto-hippocampal and subcortical sleep-wake circuits. It is hypothesized that each of these local sleep deficits arise from distinct network-specific dysfunctions driven by regionally-specific accumulation of AD pathologies, as well as their associated neurodegeneration. Overall, the evolution of these local sleep deficits offer unique windows into the circuit-specific progression of distinct AD pathophysiological processes prior to AD onset, as well as their impact on brain function. This includes the potential erosion of sleep-dependent memory mechanisms, which may contribute to memory decline in AD. This review closes with a discussion of the remaining critical knowledge gaps and implications of this work for future mechanistic studies and studies implementing sleep-based treatment interventions.

How to optimize knowledge construction in the brain

Well-structured knowledge allows us to quickly understand the world around us and make informed decisions to adequately control behavior. Knowledge structures, or schemas, are presumed to aid memory encoding and consolidation of new experiences so we cannot only remember the past, but also guide behavior in the present and predict the future. However, very strong schemas can also lead to unwanted side effects such as false memories and misconceptions. To overcome this overreliance on a schema, we should aim to create robust schemas that are on the one hand strong enough to help to remember and predict, but also malleable enough to avoid such undesirable side effects. This raises the question as to whether there are ways to deliberately influence knowledge construction processes, with the goal to reach such optimally balanced schemas. Here, we will discuss how the mnemonic processes in our brains build long-term knowledge and, more specifically, how different phases of memory formation (encoding, consolidation, retrieval, and reconsolidation) contribute to this schema build-up. We finally provide ways how to best keep a balance between generalized semantic and detailed episodic memories, which can prove very useful in, e.g., educational settings.

Hacking the Brain: Dimensions of Cognitive Enhancement

In an increasingly complex information society, demands for cognitive functioning are growing steadily. In recent years, numerous strategies to augment brain function have been proposed. Evidence for their efficacy (or lack thereof) and side effects has prompted discussions about ethical, societal, and medical implications. In the public debate, cognitive enhancement is often seen as a monolithic phenomenon. On a closer look, however, cognitive enhancement turns out to be a multifaceted concept: There is not one cognitive enhancer that augments brain function per se, but a great variety of interventions that can be clustered into biochemical, physical, and behavioral enhancement strategies. These cognitive enhancers differ in their mode of action, the cognitive domain they target, the time scale they work on, their availability and side effects, and how they differentially affect different groups of subjects. Here we disentangle the dimensions of cognitive enhancement, review prominent examples of cognitive enhancers that differ across these dimensions, and thereby provide a framework for both theoretical discussions and empirical research.

Modelling PTSD diagnosis using sleep, memory, and adrenergic metabolites: An exploratory machine-learning study

OBJECTIVE

Features of posttraumatic stress disorder (PTSD) typically include sleep disturbances, impaired declarative memory, and hyperarousal. This study evaluated whether these combined features may accurately delineate pathophysiological changes associated with PTSD.

METHOD

We recruited a cohort of PTSD-diagnosed individuals (N = 20), trauma survivors without PTSD (TE; N = 20), and healthy controls (HC; N = 20). Analyses of between-group differences and support vector machine (SVM)-learning were applied to participant features.

RESULTS

Analyses of between-group differences replicated previous findings, indicating that PTSD-diagnosed individuals self-reported poorer sleep quality, objectively demonstrated less sleep depth, and evidenced declarative memory deficits in comparison to HC. Integrative SVM-learning distinguished HC from trauma participants with 80% accuracy using a combination of five features, including subjective and objective sleep, neutral declarative memory, and metabolite variables. PTSD and TE participants could be distinguished with 70% accuracy using a combination of subjective and objective sleep variables but not by metabolite or declarative memory variables.

CONCLUSION

From among a broad range of sleep, cognitive, and biochemical variables, sleep characteristics were the primary features that could differentiate those with PTSD from those without. Our exploratory SVM-learning analysis establishes a framework for future sleep- and memory-based PTSD investigations that could drive improvements in diagnostic accuracy and treatment.

Infant wake after sleep onset serves as a marker for different trajectories in cognitive development

BACKGROUND

Sleep variables have been linked to improved functioning of learning and memory throughout life, with most studies focusing on older children and adults. Since infancy is a time of outstanding plasticity, sleep variables could be particularly important for cognitive development in that age group.

METHODS

This is a longitudinal study collecting data from 40 infants at four different time points of 4, 6, 8 and 10 months. Sleep variables were assessed using actigraphy for a week, as well as a sleep questionnaire. Eye-tracking was employed to examine developmental cognitive trajectories. Infants had to remember the location of a toy that had previously been linked to a sound and an eye-tracker recorded whether they were searching the correct location upon hearing the sound.

RESULTS

Based on their trajectories between 4 and 10 months, infants were divided into two groups who shifted their response strategies at different time points. Those two groups also differed in other aspects of their looking patterns and scored increasingly differently in the Ages & Stages Questionnaire over time. Time spent awake in the night early in life was reduced in the group who changed their strategy earlier.

CONCLUSIONS

While previous research examined the relation of infant sleep and cognitive functioning measured once, this paper provides first evidence that night wake time can serve as a marker for different cognitive trajectories.

Unlearning implicit social biases during sleep: A failure to replicate

A 2015 article in Science (Hu et al.) proposed a new way to reduce implicit racial and gender biases during sleep. The method built on an existing counter-stereotype training procedure, using targeted memory reactivation to strengthen counter-stereotype memory by playing cues associated with the training during a 90min nap. If effective, this procedure would have potential real-world usefulness in reducing implicit biases and their myriad effects. We replicated this procedure on a sample of n = 31 college students. Contrary to the results reported by Hu et al., we found no effect of cueing on implicit bias, either immediately following the nap or one week later. In fact, bias was non-significantly greater for cued than for uncued stimuli. Our failure to detect an effect of cueing on implicit bias could indicate either that the original report was a false positive, or that the current study is a false negative. However, several factors argue against Type II error in the current study. Critically, this replication was powered at 0.9 for detecting the originally reported cueing effect. Additionally, the 95% confidence interval for the cueing effect in the present study did not overlap with that of the originally reported effect; therefore, our observations are not easily explained as a noisy estimate of the same underlying effect. Ultimately, the outcome of this replication study reduces our confidence that cueing during sleep can reduce implicit bias.

The interplay between neuroendocrine and sleep alterations following traumatic brain injury

BACKGROUND

Sleep and endocrine disruptions are prevalent after traumatic brain injury (TBI) and are likely to contribute to morbidity.

OBJECTIVE

To describe the interaction between sleep and hormonal regulation following TBI and elucidate the impact that alterations of these systems have on cognitive responses during the posttraumatic chronic period.

METHODS

Review of preclinical and clinical literature describing long-lasting endocrine dysregulation and sleep alterations following TBI. The bidirectional relationship between sleep and hormones is described. Literature describing co-occurrence between sleep-wake disturbances and hormonal dysregulation will be presented. Review of literature describing cognitive effects of seep and hormones. The cognitive and functional impact of sleep disturbances and hormonal dysregulation is discussed within the context of TBI.

RESULTS/CONCLUSIONS

Sleep and hormonal alterations impact cognitive and functional outcome after TBI. Diagnosis and treatment of these disturbances will impact recovery following TBI and should be considered in the post-acute rehabilitative setting.

Deconstructing Procedural Memory: Different Learning Trajectories and Consolidation of Sequence and Statistical Learning

Procedural learning is a fundamental cognitive function that facilitates efficient processing of and automatic responses to complex environmental stimuli. Here, we examined training-dependent and off-line changes of two sub-processes of procedural learning: namely, sequence learning and statistical learning. Whereas sequence learning requires the acquisition of order-based relationships between the elements of a sequence, statistical learning is based on the acquisition of probabilistic associations between elements. Seventy-eight healthy young adults (58 females and 20 males) completed the modified version of the Alternating Serial Reaction Time task that was designed to measure Sequence and Statistical Learning simultaneously. After training, participants were randomly assigned to one of three conditions: active wakefulness, quiet rest, or daytime sleep. We examined off-line changes in Sequence and Statistical Learning as well as further improvements after extended practice. Performance in Sequence Learning increased during training, while Statistical Learning plateaued relatively rapidly. After the off-line period, both the acquired sequence and statistical knowledge was preserved, irrespective of the vigilance state (awake, quiet rest or sleep). Sequence Learning further improved during extended practice, while Statistical Learning did not. Moreover, within the sleep group, cortical oscillations and sleep spindle parameters showed differential associations with Sequence and Statistical Learning. Our findings can contribute to a deeper understanding of the dynamic changes of multiple parallel learning and consolidation processes that occur during procedural memory formation.

Overnight memory consolidation facilitates rather than interferes with new learning of similar materials-a study probing NMDA receptors

Although sleep-dependent consolidation and its neurochemical underpinnings have been strongly researched, less is known about how consolidation during sleep affects subsequent learning. Since sleep enhances memory, it can be expected to pro-actively interfere with learning after sleep, in particular of similar materials. This pro-active interference should be enhanced by substances that benefit consolidation during sleep, such as D-cycloserine. We tested this hypothesis in two groups (Sleep, Wake) of young healthy participants receiving on one occasion D-cycloserine (175 mg) and on another occasion placebo, according to a double-blind balanced crossover design. Treatment was administered after participants had learned a set of word pairs (A-B list) and before nocturnal retention periods of sleep vs. wakefulness. After D-cycloserine blood plasma levels had dropped to negligible amounts, i.e., the next day in the evening, participants learned, in three sequential runs, new sets of word pairs. One list-to enhance interference-consisted of the same cue words as the original set paired with a new target word (A-C list) and the other of completely new cue words (D-E set). Unexpectedly, during post-retention learning the A-C interference list was generally better learned than the completely new D-E list, which suggests that consolidation of previously encoded similar material enhances memory integration rather than pro-active interference. Consistent with this view, new learning of word pairs was better after sleep than wakefulness. Similarly, D-cycloserine generally enhanced learning of new word pairs, compared to placebo. This effect being independent of sleep or wakefulness, leads us to speculate that D-cycloserine, in addition to enhancing sleep-dependent consolidation, might mediate a time-dependent process of active forgetting.

REM deprivation but not sleep fragmentation produces a sex-specific impairment in extinction

REM sleep is essential for learning and memory processes, particularly emotional learning. Manipulations of REM sleep impair learning and memory and sleep architecture is often altered following a learning experience; for example, short term REM deprivation immediately after fear conditioning results in impaired extinction. In light of research demonstrating sex-dependent differences in fear conditioning as well as differences in sleep architecture, the present study investigated the effects of short term REM deprivation on the extinction of conditioned fear in male and female rats. In addition, given evidence that sleep fragmentation, which is a consequence of REM deprivation, can negatively impact learning and memory, this manipulation was compared to REM deprivation and a control condition. Male and female rats were exposed to fear conditioning followed by 6 h of REM deprivation, sleep fragmentation, or a control condition. Two extinction sessions were conducted at 48 h intervals after conditioning. REM deprivation, but not sleep fragmentation or the control condition, impaired extinction of conditioned fear. However, this effect was seen only in male rats. This study is the first to explore the effects of sleep manipulations on memory in female rats and suggests that female rats are more resilient to the deleterious effects of REM deprivation. In addition, it demonstrates that REM deprivation but not fragmentation of sleep is responsible for impairment in extinction of conditioned fear.

Adult Gross Motor Learning and Sleep: Is There a Mutual Benefit?

Posttraining consolidation, also known as offline learning, refers to neuroplastic processes and systemic reorganization by which newly acquired skills are converted from an initially transient state into a more permanent state. An extensive amount of research on cognitive and fine motor tasks has shown that sleep is able to enhance these processes, resulting in more stable declarative and procedural memory traces. On the other hand, limited evidence exists concerning the relationship between sleep and learning of gross motor skills. We are particularly interested in this relationship with the learning of gross motor skills in adulthood, such as in the case of sports, performing arts, devised experimental tasks, and rehabilitation practice. Thus, the present review focuses on sleep and gross motor learning (GML) in adults. The literature on the impact of sleep on GML, the consequences of sleep deprivation, and the influence of GML on sleep architecture were evaluated for this review. While sleep has proven to be beneficial for most gross motor tasks, sleep deprivation in turn has not always resulted in performance decay. Furthermore, correlations between motor performance and sleep parameters have been found. These results are of potential importance for integrating sleep in physiotherapeutic interventions, especially for patients with impaired gross motor functions.

Lack of frequency-tagged magnetic responses suggests statistical regularities remain undetected during NREM sleep

Hypnopedia, or the capacity to learn during sleep, is debatable. De novo acquisition of reflex stimulus-response associations was shown possible both in man and animal. Whether sleep allows more sophisticated forms of learning remains unclear. We recorded during diurnal Non-Rapid Eye Movement (NREM) sleep auditory magnetoencephalographic (MEG) frequency-tagged responses mirroring ongoing statistical learning. While in NREM sleep, participants were exposed at non-awakenings thresholds to fast auditory streams of pure tones, either randomly organized or structured in such a way that the stream statistically segmented in sets of 3 elements (tritones). During NREM sleep, only tone-related frequency-tagged MEG responses were observed, evidencing successful perception of individual tones. No participant showed tritone-related frequency-tagged responses, suggesting lack of segmentation. In the ensuing wake period however, all participants exhibited robust tritone-related responses during exposure to statistical (but not random) streams. Our data suggest that associations embedded in statistical regularities remain undetected during NREM sleep, although implicitly learned during subsequent wakefulness. These results suggest intrinsic limitations in de novo learning during NREM sleep that might confine the NREM sleeping brain's learning capabilities to simple, elementary associations. It remains to be ascertained whether it similarly applies to REM sleep.

Shaping memory consolidation via targeted memory reactivation during sleep

Recent studies have shown that the reactivation of specific memories during sleep can be modulated using external stimulation. Specifically, it has been reported that matching a sensory stimulus (e.g., odor or sound cue) with target information (e.g., pairs of words, pictures, and motor sequences) during wakefulness, and then presenting the cue alone during sleep, facilitates memory of the target information. Thus, presenting learned cues while asleep may reactivate related declarative, procedural, and emotional material, and facilitate the neurophysiological processes underpinning memory consolidation in humans. This paradigm, which has been named targeted memory reactivation, has been successfully used to improve visuospatial and verbal memories, strengthen motor skills, modify implicit social biases, and enhance fear extinction. However, these studies also show that results depend on the type of memory investigated, the task employed, the sensory cue used, and the specific sleep stage of stimulation. Here, we present a review of how memory consolidation may be shaped using noninvasive sensory stimulation during sleep.

Metabolic and Cognitive Outcomes of Subchronic Once-Daily Intranasal Insulin Administration in Healthy Men

Insulin acts in the brain to limit food intake and improve memory function. We have previously shown that 8 weeks of intranasal insulin delivered in four daily doses of 40 IU decrease body weight and enhance word list recall. In the present study, we investigated the effect on body composition, endocrine parameters, and memory performance of 8 weeks of once-daily administration of 160 IU in healthy men. We assumed that intranasal insulin administered before nocturnal sleep, a period of relative metabolic inactivity that moreover benefits memory formation, would be superior to insulin delivery in the morning and placebo administration. After a 2-week baseline period, healthy male normal-weight subjects (mean age, 27.1 ± 0.9 years) received either placebo, 160 IU intranasal insulin in the morning, or 160 IU in the evening (n = 12 per group) for 8 consecutive weeks. Throughout the experiment, we measured body weight and body composition as well as circulating concentrations of glucose, insulin, adrenocorticotropin, cortisol, growth hormone, insulin-like growth-factor 1, adiponectin, and leptin. Declarative and procedural memory function was repeatedly assessed by means of, respectively, word list recall and word-stem priming. We found that neither morning nor evening insulin compared to placebo administration induced discernible changes in body weight and body composition. Delayed recall of words showed slight improvements by insulin administration in the evening, and serum cortisol concentrations were reduced after 2 weeks of insulin administration in the morning compared to the other groups. Results indicate that catabolic long-term effects of central nervous insulin delivery necessitate repetitive, presumably pre-meal delivery schedules. The observed memory improvements, although generally weaker than previously found effects, suggest that sleep after intranasal insulin administration may support its beneficial cognitive impact.

Optimizing learning in undergraduate psychology students: the impact of advance quizzing, review, and classroom attendance

This study investigates whether introducing simple cognitive interventions that are known to enhance learning in laboratory studies can be transferred to classroom settings. In an introductory psychology class, students were provided with a brief advance quiz on the topic covered in each particular lecture. In case they did not attend class, they still had the opportunity to fill it out at home. The interventions were offered on a voluntary basis and the students were given the opportunity to obtain an extra point towards the final exam by reviewing the key points of each lecture on a regular basis. The results indicate that both advance quizzing and review enhanced the grades on the final examination. Although it is likely that individual differences also contribute to learning outcomes, these effects were specific for the particular course and independent from class attendance. The results indicate that transfer of simple cognitive interventions from laboratory to classroom settings is feasible. They also indicate that these interventions can be effectively implemented into the lectures to boost student learning.

Imbalance between TNFα and progranulin contributes to memory impairment and anxiety in sleep-deprived mice

Sleep disorder is becoming a widespread problem in current society, and is associated with impaired cognition and emotional disorders. Progranulin (PGRN), also known as granulin epithelin precursor, promotes neurite outgrowth and cell survival, and is encoded by the GRN gene. It is a tumor necrosis factor α receptor (TNFR) ligand which is implicated in many central nervous system diseases. However, the role PGRN in sleep disorder remains unclear. In the present study, we found that sleep deprivation (S-DEP) impaired the memory and produced thigmotaxis/anxiety-like behaviors in mice. S-DEP increased the levels of TNFα but decreased PGRN levels in the hippocampus. The intracerebroventricular (ICV) injection of PGRN or intraperitoneal injection of TNFα synthesis blocker thalidomide (25 mg/kg), prevented the memory impairment and anxiety behaviors induced by S-DEP. PGRN treatment also restored dendritic spine density in the hippocampus CA1 region and neurogenesis in hippocampus dentate gyrus (DG). These results indicate that an imbalance between TNFα and PGRN contributes to memory impairment and thigmotaxis/anxiety caused by sleep deprivation.

Sculpting memory during sleep: concurrent consolidation and forgetting

There is compelling evidence that sleep actively supports the formation of long-lasting memory representations. Experimental cuing of memories proved that neural replay of representations during sleep plays a causal role for this consolidation, which has also been shown to promote neocortical synaptic plasticity and spine formation. Concurrently, sleep has been proposed to facilitate forgetting through processes of synaptic renormalisation. This view received indirect support by findings in humans of sleep enhancing TMS-evoked plasticity and capabilities for encoding new information. First direct behavioural evidence of sleep inducing forgetting has only recently emerged after encoding large amounts of stimuli in adults. We propose forgetting complements sleep-dependent consolidation and facilitates gist abstraction especially at high memory loads, when reactivation-based consolidation reaches capacity limits.

The role of sleep in recovery following ischemic stroke: A review of human and animal data

Despite advancements in understanding the pathophysiology of stroke and the state of the art in acute management of afflicted patients as well as in subsequent neurorehabilitation training, stroke remains the most common neurological cause of long-term disability in adulthood. To enhance stroke patients' independence and well-being it is necessary, therefore, to consider and develop new therapeutic strategies and approaches. We postulate that sleep might play a pivotal role in neurorehabilitation following stroke. Over the last two decades compelling evidence for a major function of sleep in neuroplasticity and neural network reorganization underlying learning and memory has evolved. Training and learning of new motor skills and knowledge can modulate the characteristics of subsequent sleep, which additionally can improve memory performance. While healthy sleep appears to support neuroplasticity resulting in improved learning and memory, disturbed sleep following stroke in animals and humans can impair stroke outcome. In addition, sleep disorders such as sleep disordered breathing, insomnia, and restless legs syndrome are frequent in stroke patients and associated with worse recovery outcomes. Studies investigating the evolution of post-stroke sleep changes suggest that these changes might also reflect neural network reorganization underlying functional recovery. Experimental and clinical studies provide evidence that pharmacological sleep promotion in rodents and treatment of sleep disorders in humans improves functional outcome following stroke. Taken together, there is accumulating evidence that sleep represents a "plasticity state" in the process of recovery following ischemic stroke. However, to test the key role of sleep and sleep disorders for stroke recovery and to better understand the underlying molecular mechanisms, experimental research and large-scale prospective studies in humans are necessary. The effects of hospital conditions, such as adjusting light conditions according to the patients' sleep-wake rhythms, or sleep promoting drugs and non-invasive brain stimulation to promote neuronal plasticity and recovery following stroke requires further investigation.

The relationship of medial temporal lobe epilepsy with the declarative memory system

Introduction.Medial temporal lobe of epilepsy (MTLE) is considered as local/regional epilepsy. However, as was discussed in Part I of this review (Halász, 2016a) there is more evidence regarding the involvement of both temporal lobes so as to consider MTLE as one of the typical bilateral system epilepsies.

Aim.To provide contemporary review of MTLE in relation to the declarative memory system and the newly recognized hippocampo-frontal memory consolidation during slow wave sleep.

Methods.A review of the available literature on experimental and clinical data and also the authors own studies in MTLE patients.

Review, discussion and results.New experimental and clinical neurophysiological data have shown that MTLE is closely linked to the hippocampal memory system. It is likely that hippocampal spiking is the epileptic variations of the normal sharp wave ripple events mediating the encoding and consolidation of memory engrams by a hippocampo-frontal dialogue during slow wave sleep.

Conclusions.The source of memory impairment in MTLE patients is not merely the cell loss and synaptic transformation of the hippocampal structure, but the every night interference with memory consolidation due to interictal spiking.

The Limited Capacity of Sleep-Dependent Memory Consolidation

Sleep supports memory consolidation. However, the conceptually important influence of the amount of items encoded in a memory test on this effect has not been investigated. In two experiments, participants (n = 101) learned lists of word-pairs varying in length (40, 160, 320 word-pairs) in the evening before a night of sleep (sleep group) or of sleep deprivation (wake group). After 36 h (including a night allowing recovery sleep) retrieval was tested. Compared with wakefulness, post-learning sleep enhanced retention for the 160 word-pair condition (p < 0.01), importantly, this effect completely vanished for the 320 word-pair condition. This result indicates a limited capacity for sleep-dependent memory consolidation, which is consistent with an active system consolidation view on sleep's role for memory, if it is complemented by processes of active forgetting and/or gist abstraction. Whereas the absolute benefit from sleep should have increased with increasing amounts of successfully encoded items, if sleep only passively protected memory from interference. Moreover, the finding that retention performance was significantly diminished for the 320 word-pair condition compared to the 160 word-pair condition in the sleep group, makes it tempting to speculate that with increasing loads of information encoded during wakefulness, sleep might favor processes of forgetting over consolidation.

The Effect of Sleep on Children's Word Retention and Generalization

In the first few years of life children spend a good proportion of time sleeping as well as acquiring the meanings of hundreds of words. There is now ample evidence of the effects of sleep on memory in adults and the number of studies demonstrating the effects of napping and nocturnal sleep in children is also mounting. In particular, sleep appears to benefit children's memory for recently-encountered novel words. The effect of sleep on children's generalization of novel words across multiple items, however, is less clear. Given that sleep is polyphasic in the early years, made up of multiple episodes, and children's word learning is gradual and strengthened slowly over time, it is highly plausible that sleep is a strong candidate in supporting children's memory for novel words. Importantly, it appears that when children sleep shortly after exposure to novel word-object pairs retention is better than if sleep is delayed, suggesting that napping plays a vital role in long-term word retention for young children. Word learning is a complex, challenging, and important part of development, thus the role that sleep plays in children's retention of novel words is worthy of attention. As such, ensuring children get sufficient good quality sleep and regular opportunities to nap may be critical for language acquisition.

Loss of promoter IV-driven BDNF expression impacts oscillatory activity during sleep, sensory information processing and fear regulation

Posttraumatic stress disorder is characterized by hyperarousal, sensory processing impairments, sleep disturbances and altered fear regulation; phenotypes associated with changes in brain oscillatory activity. Molecules associated with activity-dependent plasticity, including brain-derived neurotrophic factor (BDNF), may regulate neural oscillations by controlling synaptic activity. BDNF synthesis includes production of multiple Bdnf transcripts, which contain distinct 5' noncoding exons. We assessed arousal, sensory processing, fear regulation and sleep in animals where BDNF expression from activity-dependent promoter IV is disrupted (Bdnf-e4 mice). Bdnf-e4 mice display sensory hyper-reactivity and impaired electrophysiological correlates of sensory information processing as measured by event-related potentials (ERP). Utilizing electroencephalogram, we identified a decrease in slow-wave activity during non-rapid eye movement sleep, suggesting impaired sleep homeostasis. Fear extinction is controlled by hippocampal-prefrontal cortical BDNF signaling, and neurophysiological communication patterns between the hippocampus (HPC) and medial prefrontal cortex (mPFC) correlate with behavioral performance during extinction. Impaired fear extinction in Bdnf-e4 mice is accompanied by increased HPC activation and decreased HPC-mPFC theta phase synchrony during early extinction, as well as increased mPFC activation during extinction recall. These results suggest that activity-dependent BDNF signaling is critical for regulating oscillatory activity, which may contribute to altered behavior.

Efficacy of sleep education in a Dominican Republic neighborhood through training of community health promoters

INTRODUCTION

The Children's Hospital of Philadelphia (CHOP) Global Health Allies program in the Dominican Republic trains nine health promoters (HPs) in various health subjects with the goal to educate the community. This time we evaluated our teaching session on sleep and sleep disorders.

METHODS

Questionnaires were randomly administered to HPs, and community members in the Dominican Republic before and after the HP educational intervention. Nine HPs already enrolled in the CHOP program, received a 4-hour training session in sleep and sleep disorders. HPs were then instructed to educate the community as they usually do during their supervised weekly home visits.

RESULTS

The nine HP demonstrated knowledge of sleep disorders in their post-training assessment. In the community, 93 adults responded to the initial questionnaire. Although 92 (99%) stated that sleep is important, very few knew about obstructive sleep apnea (n = 17; 18%) and narcolepsy (n = 11; 12%). The post-education questionnaire revealed no statistically significant change in the knowledge about sleep and sleep disorders in the community.

CONCLUSION

The HP knowledge about sleep disorders improved after a 4-hour training session. The community knowledge did not change after education by HPs. Barriers to community education must be explored and the need for other forms of community education about sleep and sleep disorders should be addressed.

Naps promote flexible memory retrieval in 12-month-old infants

Flexibility in applying existing knowledge to similar cues is a corner stone of memory development in infants. Here, we examine the effect of sleep on the flexibility of memory retrieval using a deferred imitation paradigm. Forty-eight 12-month-old infants were randomly assigned to either a nap or a no-nap demonstration condition (scheduled around their natural daytime sleep schedule) or to a baseline control condition. In the demonstration conditions, infants watched an experimenter perform three target actions on a hand puppet. Immediately afterwards, infants were allowed to practice the target actions three times. In a test session 4-hr later, infants were given the opportunity to reproduce the actions with a novel hand puppet differing in color from the puppet used during the demonstration session. Only infants in the nap-condition performed significantly more target actions than infants in the baseline control condition. Furthermore, they were faster to carry out the first target action than infants in the no-nap condition. We conclude that sleep had a facilitative effect on infants' flexibility of memory retrieval.

Central Nervous Insulin Signaling in Sleep-Associated Memory Formation and Neuroendocrine Regulation

The neurochemical underpinnings of sleep's contribution to the establishment and maintenance of memory traces are largely unexplored. Considering that intranasal insulin administration to the CNS improves memory functions in healthy and memory-impaired humans, we tested whether brain insulin signaling and sleep interact to enhance memory consolidation in healthy participants. We investigated the effect of intranasal insulin on sleep-associated neurophysiological and neuroendocrine parameters and memory consolidation in 16 men and 16 women (aged 18-30 years), who learned a declarative word-pair task and a procedural finger sequence tapping task in the evening before intranasal insulin (160 IU) or placebo administration and 8 h of nocturnal sleep. On the subsequent evening, they learned interfering word-pairs and a new finger sequence before retrieving the original memories. Insulin increased growth hormone concentrations in the first night-half and EEG delta power during the second 90 min of non-rapid-eye-movement sleep. Insulin treatment impaired the acquisition of new contents in both the declarative and procedural memory systems on the next day, whereas retrieval of original memories was unchanged. Results indicate that sleep-associated memory consolidation is not a primary mediator of insulin's acute memory-improving effect, but that the peptide acts on mechanisms that diminish the subsequent encoding of novel information. Thus, by inhibiting processes of active forgetting during sleep, central nervous insulin might reduce the interfering influence of encoding new information.

Sleep and Motor Learning: Implications for Physical Rehabilitation After Stroke

Sleep is essential for healthy brain function and plasticity underlying learning and memory. In the context of physical impairment such as following a stroke, sleep may be particularly important for supporting critical recovery of motor function through similar processes of reorganization in the brain. Despite a link between stroke and poor sleep, current approaches to rehabilitative care often neglect the importance of sleep in clinical assessment and treatment. This review assimilates current evidence on the role of sleep in motor learning, with a focus on the implications for physical rehabilitation after stroke. We further outline practical considerations for integrating sleep assessment as a vital part of clinical care.

Healthy Aging Promotion through Neuroscientific Information-Based Strategies

To ensure the well-being of a rapidly growing elderly population, it is fundamental to find strategies to foster healthy brain aging. With this intention, we designed a program of scientific-based lectures aimed at dissemination by established neuroscientists about brain function, brain plasticity and how lifestyle influences the brain. We also carried out a pilot study on the impact of the lectures on attendees. The objective was to provide information to elderly people in order to encourage them to identify unhealthy and healthy daily habits, and more importantly, to promote behavioral changes towards healthy brain aging. Here we report on our experience. In order to determine the impact of the lectures in the daily routine of the attendees, we asked them to fill out questionnaires. Preliminary results indicate that neuroscientific information-based strategies can be a useful method to have a positive impact on the lives of elderly, increase their awareness on how to improve brain function and promote positive lifestyle modifications. Furthermore, based on self-reported data, we also found that through this strategy it is possible to promote behavioral changes related to nutrition, sleep, and realization of physical and cognitively stimulating activities. Finally, based on the results obtained, the importance of promoting self-efficacy and the empowerment of the older populations is highlighted.