Isolated cortical computations during delta waves support memory consolidation

International audienceDelta waves have been described as periods of generalized silence across the cortex , and their alternation with periods of endogenous activity results in the slow oscillation of slow wave sleep. Despite evidence that delta waves are instrumental for memory consolidation, their specific role in reshaping cortical functional circuits remains puzzling. We found that delta waves are not periods of complete silence, and the residual activity is not mere neuronal noise. Instead, cortical cells involved in learning a spatial memory task subsequently formed cell assemblies during delta waves in response to transient reactivation of hippocampal ensembles during ripples. This occurred selectively during endogenous or induced memory consolidation. Thus, delta waves represent isolated cortical computations tightly related to ongoing information processing underlying memory consolidation

Nested sequences of hippocampal assemblies during behavior support subsequent sleep replay

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The College Application Essay Mediating Inequality Along the Path to Higher Education

This dissertation examines inequality and access in the college admissions process and, in particular, via the college application essay. With a research design and analysis sampling documents from multiple stakeholders in the college admissions process, this research considers how students with diverse histories of preparation for higher education interact with actors relevant to the admissions process in their college admissions essays. This research project ultimately asks how the college essay process (its importance, the preparation, and ultimate writing) mediates inequality in admission to higher education. Essays were collected from students at one large public university and one small private liberal arts university. These were analyzed alongside university admissions requirements and college preparatory agency information. Analyses showed that all student essays interacted with the institutional expectations and presented an awareness of the need to write for their audience. Students addressed their audience more and less directly, by conveying challenges they overcame and describing the personal growth that came from those challenges. Differences in essays by students across public and private universities emerged in how the students approached challenges and development. For example, first-generation college students and those who did not participate in college preparatory activities devoted more words to describing the challenge itself, whereas their non-first-generation peers and those that were exposed to college preparatory work devoted more attention to exploring the development of their passions. This study sheds light on how students use the college essay process to negotiate their understanding of higher education and their potential place in it, in relation to numerous messages they have received. That said, barriers to higher education access remain. The findings can help researchers consider innovative designs for studying inequality and for considering practices of educators, policy makers, and families to better understand the college process

Locus coeruleus noradrenergic neurons phase-lock to prefrontal and hippocampal infra-slow rhythms that synchronize to behavioral events

The locus coeruleus (LC) is the primary source of noradrenergic projections to the forebrain, and, in prefrontal cortex, is implicated in decision-making and executive function. LC neurons phase-lock to cortical infra-slow wave oscillations during sleep. Such infra-slow rhythms are rarely reported in awake states, despite their interest, since they correspond to the time scale of behavior. Thus, we investigated LC neuronal synchrony with infra-slow rhythms in awake rats performing an attentional set-shifting task. Local field potential (LFP) oscillation cycles in prefrontal cortex and hippocampus on the order of 0.4 Hz phase-locked to task events at crucial maze locations. Indeed, successive cycles of the infra-slow rhythms showed different wavelengths, as if they are periodic oscillations that can reset phase relative to salient events. Simultaneously recorded infra-slow rhythms in prefrontal cortex and hippocampus could show different cycle durations as well, suggesting independent control. Most LC neurons (including optogenetically identified noradrenergic neurons) recorded here were phase-locked to these infra-slow rhythms, as were hippocampal and prefrontal units recorded on the LFP probes. The infra-slow oscillations also phase-modulated gamma amplitude, linking these rhythms at the time scale of behavior to those coordinating neuronal synchrony. This would provide a potential mechanism where noradrenaline, released by LC neurons in concert with the infra-slow rhythm, would facilitate synchronization or reset of these brain networks, underlying behavioral adaptation

Results obtained with EVOagri technology to improve yield using filtered water in Africa, Tibet, Italy and Bulgaria

The effectiveness of the application of EVOagri technology for purification of water and its use in agriculture in some African countries (Zimbabwe, Burundi, Egypt and Uganda), Nepal (Asia) and in Europe (Italy and Bulgaria) was evaluated. The performance of EVOdrop turbine for water filtration was analysed and the physicochemical composition of water was tested. This was determined in compliance with Ordinance No. 9/2001, published in the Official State Gazette, issue 30, and decree No. 178/23.07.2004, Bulgaria, European Union on the quality of water intended for drinking and household purposes. The results showed a significant increase in production yield of the tested Solanum spp. and lettuces in Zimbabwe, as well as of dill, spinach and onions in Egypt. Treatment of high-salt irrigation water in Burundi with EVOagri reduced its toxic effect upon vegetable plants. In Uganda, plants absorbed 23% less water, when filtered with EVOagri technology. In Italy, 21% water conservation was achieved through the usage of EVOagri technology. Stimulation of seed-germination after soaking with EVOagri water was established in Burundi and Nepal. The importance of the type and composition of irrigation water for crop growth was proved by the experiments in Bulgaria. In Bulgaria, onion seeds were planted in two separate pots. The first one was watered with tap water and this was taken as the control sample with tap water. The second one was watered with EVOdrop filtered water which was saturated with EVOdrop hydrogen technology (EVOwater). In Bulgaria, under natural conditions, Evodrop water was also tested in beans and the growth result was 11 % better than the control sample

Theoretical Analysis of Hydrogen Bonds, Energy Distribution and Information in a 1 % Rosa damascena Mill Oil Solution

The method of Non-equilibrium Energy Spectrum (NES) was applied in measurement of hydrogen bonds energy distribution in 1% Rosa damscena L. oil solution in deionized water. Local maxima in this spectrum were identical with these obtained in investigations of other biologically active solutions and related to particular bio effects as follows: (-0.1387 eV; 8.95 µm; 1117 cm-1). This local maximum is typical for antibacterial, anti-tumor and anti-inflammatory effects. The local maxima at (-0.1212 eV; 10.23 µm; 978 cm-1) and (-0.1262 eV; 9.82 µm; 1018 cm-1) are typical for anti-inflammatory effects and this at (-0.1112 eV; 11.15 µm; 897 cm-1) is typical for effects on the nervous system and nerve conductivity. Information theoretical analysis was performed using the values of Shannon entropy and Transformational information entropy, pointing to hydrogen bonds distribution similarities between Rosa damscena L., V. myrtillus L. and Salvia divinorum Epling. The possible chemical causes of these similarities were identified as antioxidant activity and polyphenols concentration

Improving college students’ fact-checking strategies through lateral reading instruction in a general education civics course

College students lack fact-checking skills, which may lead them to accept information at face value. We report findings from an institution participating in the Digital Polarization Initiative (DPI), a national effort to teach students lateral reading strategies used by expert fact-checkers to verify online information. Lateral reading requires users to leave the information (website) to find out whether someone has already fact-checked the claim, identify the original source, or learn more about the individuals or organizations making the claim. Instructor-matched sections of a general education civics course implemented the DPI curriculum (N=136 students) or provided business-as-usual civics instruction (N=94 students). At posttest, students in DPI sections were more likely to use lateral reading to fact-check and correctly evaluate the trustworthiness of information than controls. Aligning with the DPI’s emphasis on usingWikipedia to investigate sources, students in DPI sections reported greater use of Wikipedia at posttest than controls, but did not differ significantly in their trust of Wikipedia. In DPI sections, students who failed to read laterally at posttest reported higher trust of Wikipedia at pretest than students who read at least one problem laterally. Responsiveness to the curriculum was also linked to numbers of online assignments attempted, but unrelated to pretest media literacy knowledge, use of lateral reading, or self-reported use of lateral reading. Further research is needed to determine whether improvements in lateral reading are maintained over time and to explore other factors that might distinguish students whose skills improved after instruction from non-responders

MSL2 variants lead to a neurodevelopmental syndrome with lack of coordination, epilepsy, specific dysmorphisms, and a distinct episignature.

Epigenetic dysregulation has emerged as an important etiological mechanism of neurodevelopmental disorders (NDDs). Pathogenic variation in epigenetic regulators can impair deposition of histone post-translational modifications leading to aberrant spatiotemporal gene expression during neurodevelopment. The male-specific lethal (MSL) complex is a prominent multi-subunit epigenetic regulator of gene expression and is responsible for histone 4 lysine 16 acetylation (H4K16ac). Using exome sequencing, here we identify a cohort of 25 individuals with heterozygous de novo variants in MSL complex member MSL2. MSL2 variants were associated with NDD phenotypes including global developmental delay, intellectual disability, hypotonia, and motor issues such as coordination problems, feeding difficulties, and gait disturbance. Dysmorphisms and behavioral and/or psychiatric conditions, including autism spectrum disorder, and to a lesser extent, seizures, connective tissue disease signs, sleep disturbance, vision problems, and other organ anomalies, were observed in affected individuals. As a molecular biomarker, a sensitive and specific DNA methylation episignature has been established. Induced pluripotent stem cells (iPSCs) derived from three members of our cohort exhibited reduced MSL2 levels. Remarkably, while NDD-associated variants in two other members of the MSL complex (MOF and MSL3) result in reduced H4K16ac, global H4K16ac levels are unchanged in iPSCs with MSL2 variants. Regardless, MSL2 variants altered the expression of MSL2 targets in iPSCs and upon their differentiation to early germ layers. Our study defines an MSL2-related disorder as an NDD with distinguishable clinical features, a specific blood DNA episignature, and a distinct, MSL2-specific molecular etiology compared to other MSL complex-related disorders

Profils d'activité neurale lors d'événements oscillatoires soutendant la consolidation des souvenirs dépendant de l'hippocampe

Long term storage of episodic memories requires memory formation during awake experience as well as memory consolidation, a process strengthening the memory taking place during sleep. The rapid encoding of memory traces takes place in the hippocampus during awake behaviour. In sleep, hippocampal memory traces are `replayed' during sharp wave-ripples -- brief (50-150 ms) high-frequency oscillatory patterns of high synchronous activity. The synchronous bursting of hippocampal neurons during ripples makes them a key player in systems memory consolidation -- the process of communicating memories to the neocortex for long-term storage.Cortical activity in sleep is dominated by the slow oscillation -- the synchronous alternation of cortical neurons between a depolarised (UP) state associated with high levels of endogenous activity, and a brief (~200 ms) hyperpolarized (DOWN) state when neurons remain silent. DOWN states are accompanied by large deflections of the local field potential -- delta waves, while UP states bring elevated activity and thalamocortical spindles, both of which can drive synaptic plasticity. Systems memory consolidation is thought to involve the coordination between hippocampal and cortical rhythms -- notably, hippocampal ripples precede (~130 ms) cortical delta waves, which are then followed by thalamocortical spindles.To test if this temporal coupling drives memory consolidation, we triggered cortical delta waves following ripples to enhance the co-occurrence of coupled ripple-delta events. This boosted memory consolidation and rat performance on a spatial memory task, and resulted in a reorganisation of prefrontal cortical networks following induced delta waves as well as increased prefrontal responsivity to the task on the next day. Crucially, these enhancements were not observed when a small delay (160-240 ms) was introduced in addition to the endogenous coupling, indicating the stabilization of memory traces requires a very fine-tuned interaction between ripples and delta waves.How can the 'interruption' of cortical activity by generalised periods of silence during delta waves underlie memory consolidation when it occurs precisely between information transfer (hippocampal replay) and network plasticity (UP state)? Contrary to a generally accepted tenet, we found that delta waves are not periods of complete silence, and that the residual activity is not mere neuronal noise. Instead, cortical cells fired `delta spikes' during delta waves in response to transient reactivation of hippocampal ensembles during ripples, and this occurred selectively during endogenous or induced memory consolidation. This suggests a new role for delta waves -- namely, that the synchronised silence of the large majority of cells isolates the network from competing inputs, while a select subpopulation of neurons remain active in response to hippocampal replay, bridging information between UP states and coordinating memory consolidation.Le stockage à long terme des souvenirs épisodiques requiert la formation de la mémoire pendant l'expérience d'éveil ainsi que la consolidation de la mémoire, un processus de renforcement de la mémoire qui a lieu pendant le sommeil. L'encodage rapide des traces mnésiques a lieu dans l'hippocampe pendant l'éveil. Pendant le sommeil, les traces mnésiques de l'hippocampe sont « rejouées » pendant les ondulations -- de brefs motifs oscillatoires hippocampiques (50-150 ms) à haute fréquence associés à une activité synchrone élevée. Les bouffées d'activité synchrone des neurones de l'hippocampe pendant les ondulations font d'eux des acteurs clés dans la consolidation de la mémoire des systèmes -- le processus de communication des mémoires vers le néocortex pour un stockage à long terme.L'activité corticale dans le sommeil est dominée par l'oscillation lente -- l'alternance synchrone des neurones corticaux entre un état dépolarisé (état HAUT) associé à des niveaux élevés d'activité endogène, et un état bref (~200ms) hyperpolarisé (état BAS) lorsque les neurones restent silencieux. Les états BAS sont accompagnés de grandes déviations du potentiel de champ local -- ondes delta, tandis que les états HAUTS sont associés à une activité élevée et des fuseaux thalamocorticaux, deux processus pouvant entraîner une plasticité synaptique. On pense que la consolidation de la mémoire des systèmes implique une coordination entre les rythmes hippocampiques et corticaux -- notamment, les ondulations hippocampiques précèdent (~130ms) les ondes delta corticales, qui sont ensuite suivies par des fuseaux thalamocorticaux.Pour vérifier si ce couplage temporel entraîne une consolidation de la mémoire, nous avons déclenché des ondes delta corticales suite à des ondulations hippocampiques afin d'améliorer la cooccurrence d'événements ondulation-delta couplés. Cela a augmenté la consolidation de la mémoire et la performance du rat sur une tâche de mémoire spatiale, et a entraîné une réorganisation des réseaux corticaux préfrontaux suite à des ondes delta induites ainsi qu'une réponse accrue du cortex préfrontal à la tâche le lendemain. De manière cruciale, ces améliorations n'ont pas été observées lorsqu'un retard (160-240 ms) a été introduit en plus du couplage endogène, indiquant que la stabilisation des traces mnésiques nécessite une interaction très fine entre les ondulations et les ondes delta.Comment l'interruption de l'activité corticale par des périodes de silence généralisées pendant les ondes delta peut-elle sous-tendre la consolidation de la mémoire lorsqu'elle se produit précisément entre le transfert d'informations (réactivation hippocampique) et la plasticité du réseau (état HAUT) ? Contrairement à un principe généralement accepté, nous avons constaté que les ondes delta ne sont pas des périodes de silence complet, et que l'activité résiduelle n'est pas un simple bruit neuronal. Au lieu de cela, nous avons montré que les cellules corticales émettent des « delta spikes » pendant les ondes delta en réponse à la réactivation transitoire d'ensembles hippocampiques pendant les ondulations, et que cela se produit sélectivement pendant la consolidation endogène ou induite de la mémoire. Ces résultats suggèrent un nouveau rôle pour les ondes delta, à savoir que le silence synchronisé de la grande majorité des cellules isole le réseau des entrées concurrentes, tandis qu'une sous-population sélectionnée de neurones reste active en réponse aux réactivations de l'hippocampe, faisant le pont entre les états HAUTs et coordonnant la consolidation de la mémoire

Institutional Expectations and Students’ Responses to the College Application Essay

This paper explores inequality along the path to college through an analysis of college admissions essays and institutional documents that shape admissions expectations in the United States. The research considers how successful applicants from two different universities and students who are the first in their families to go to college compared to those who are not, approach the college essay in relation to the presented institutional expectations. The sample consists of institutional materials from two universities, one a small private university and one a large public institution. Institutional materials also include documents from college preparatory agencies (such as Kaplan and Khan Academy). Thirty-five student essays were collected from the same two universities mentioned above. Through values analysis, a narrative analysis method, I ask how students with less exposure to the culture of college (taken for granted knowledge about college that is passed down from families) perform the college essay genre. Findings show that students with less exposure to the culture of college focus more on challenges and narrate less expression of their “true selves” in their college admissions essays. Findings can help stakeholders create a more equitable college admissions process that more clearly illuminates institutional expectations for students