Primed to Sleep: The Dynamics of Synaptic Plasticity Across Brain States

It is commonly accepted that brain plasticity occurs in wakefulness and sleep. However, how these different brain states work in concert to create long-lasting changes in brain circuitry is unclear. Considering that wakefulness and sleep are profoundly different brain states on multiple levels (e.g., cellular, molecular and network activation), it is unlikely that they operate exactly the same way. Rather it is probable that they engage different, but coordinated, mechanisms. In this article we discuss how plasticity may be divided across the sleep–wake cycle, and how synaptic changes in each brain state are linked. Our working model proposes that waking experience triggers short-lived synaptic events that are necessary for transient plastic changes and mark (i.e., ‘prime’) circuits and synapses for further processing in sleep. During sleep, synaptic protein synthesis at primed synapses leads to structural changes necessary for long-term information storage

Sleep maintains excitatory synapse diversity in the cortex and hippocampus

How sleep deprivation affects cognition remains elusive. Synaptome mapping of excitatory synapses in 125 regions of the mouse brain revealed that sleep deprivation selectively reduces synapse diversity in the cortex and hippocampus. Sleep deprivation targeted specific types and subtypes of excitatory synapses while maintaining total synapse density. Altered synaptic responses to neural oscillations in a computational model suggest that sleep prevents cognitive impairments by maintaining normal brain synaptome architecture

Consumers’ avoidance of information on red meat risks:information exposure effects on attitudes and perceived knowledge

In accordance with cognitive dissonance theory, individuals generally avoid information that is not consistent with their cognitions, to avoid psychological discomfort associated with tensions arising from contradictory beliefs. Information avoidance may thus make risk communication less successful. To address this, we presented information on red meat risks to red meat consumers. To explore information exposure effects, attitudes toward red meat and perceived knowledge of red meat risks were measured before, immediately after, and two weeks after exposure. We expected information avoidance of red meat risks to be: positively related to (1) study discontentment; and (2) positive attitudes toward red meat; and negatively related to (3) information seeking on red meat risks; and (4) systematic and heuristic processing of information. In addition, following exposure to the risk information, we expected that (5) individuals who scored high in avoidance of red meat risks information to change their attitudes and perceived risk knowledge less than individuals who scored low in avoidance. Results were in line with the first three expectations. Support for the fourth was partial insofar as this was only confirmed regarding systematic processing. The final prediction was not confirmed; individuals who scored high in avoidance decreased the positivity of their attitudes and increased their perceived knowledge in a similar fashion to those who scored low in avoidance. These changes stood over the two-week follow-up period. Results are discussed in accordance with cognitive dissonance theory, with the possible use of suppression strategies, and with the corresponding implications for risk communication practice

Tweeting during food crises:A psychosocial analysis of EHEC threat coping expressions in Spain, during the 2011 European EHEC outbreak

Food crises imply responses that are not what people and organisations would normally do, if one or more threats (health, economic, etc.) were not present. At an individual level, this motivates individuals to implement coping strategies aimed at adaptation to the threat that has been presented, as well as the reduction of stressful experiences. In this regard, microblogging channels such as Twitter emerge as a valuable resource to access individuals' expressions of coping. Accordingly, Twitter expressions are generally more natural, spontaneous and heterogeneous — in cognitive, affective and behavioural dimensions — than expressions found on other types of social media (e.g. blogs). Moreover, as a social media channel, it provides access not only to an individual but also to a social level of analysis, i.e. a psychosocial media analysis. To show the potential in this regard, our study analysed Twitter messages produced by individuals during the 2011 EHEC/Escherichia coli bacteria outbreak in Europe, due to contaminated food products. This involved more than 3100 cases of bloody diarrhoea and 850 of haemolytic uraemic syndrome (HUS), and 53 confirmed deaths across the EU. Based on data collected in Spain, the country initially thought to be the source of the outbreak, an initial quantitative analysis considered 11,411 tweets, of which 2099 were further analysed through a qualitative content analysis. This aimed at identifying (1) the ways of coping expressed during the crisis; and (2) how uncertainty about the contaminated product, expressed through hazard notifications, influenced the former. Results revealed coping expressions as being dynamic, flexible and social, with a predominance of accommoda- tion, information seeking and opposition (e.g. anger) strategies. The latter were more likely during a period of uncertainty, with the opposite being true for strategies relying on the identification of the contaminated product (e.g. avoid consumption/purchase). Implications for food crisis communication and monitoring systems are discussed

Spécification précoce de la topographie des projections thalamo-corticales (rôle du facteur de transcription Neurogénine-2 dans le contrôle de la réponse des axones thalamiques à des signaux intermédiaires)

Le tractus thalamo-cortical, relais essentiel de l'information sensorielle vers le néocortex, est caractérisé par une topographie stricte déterminée par une correspondance entre chaque noyau thalamique et leur aire corticale correspondante. Notre étude, in vivo et in vitro du développement des axones thalamo-corticaux, montre que la topographie thalamo-corticale s'initie dans une cible intermédiaire, le télencéphale ventral. Cette topographie de connectivite semble contrôlée intrinséquement par l'expression du facteur de transcription neurogénine-2 dans les neurones du thalamus (Seibt et al., 2003). Nous avons choisi une approche par criblage de gènes cibles sous le contrôle transcriptionnel de neurogénine-2 en utilisant une méthode de surexpression virale dans le thalamus dorsal. Un certain nombre de gènes s'expriment de manière différentielle après induction par neurogénéine-2. Notre perspective est d'étudier maintenant leur rôle dans le thalamus dorsal au cours du développementLYON1-BU.Sciences (692662101) / SudocSudocFranceF

A mechanism for learning with sleep spindles

Spindles are ubiquitous oscillations during non-rapid eye movement (NREM) sleep. A growing body of evidence points to a possible link with learning and memory, and the underlying mechanisms are now starting to be unveiled. Specifically, spindles are associated with increased dendritic activity and high intracellular calcium levels, a situation favourable to plasticity, as well as with control of spiking output by feed-forward inhibition. During spindles, thalamocortical networks become unresponsive to inputs, thus potentially preventing interference between memory-related internal information processing and extrinsic signals. At the system level, spindles are co-modulated with other major NREM oscillations, including hippocampal sharp wave-ripples (SWRs) and neocortical slow waves, both previously shown to be associated with learning and memory. The sequential occurrence of reactivation at the time of SWRs followed by neuronal plasticity-promoting spindles is a possible mechanism to explain NREM sleep-dependent consolidation of memories

Translation regulation in sleep

Sleep improves cognition and is necessary for normal brain plasticity, but the precise cellular and molecular mechanisms mediating these effects are unknown. At the molecular level, experience-dependent synaptic plasticity triggers new gene and protein expression necessary for long-lasting changes in synaptic strength.1 In particular, translation of mRNAs at remodeling synapses is emerging as an important mechanism in persistent forms of synaptic plasticity in vitro and certain forms of memory consolidation.2 We have previously shown that sleep is required for the consolidation of a canonical model of in vivo plasticity (i.e., ocular dominance plasticity [ODP] in the developing cat).3 Using this model, we recently showed that protein synthesis during sleep participates in the consolidation process. We demonstrate that activation of the mammalian target of rapamycin [mTOR] pathway, an important regulator of translation initiation,4 is necessary for sleep-dependent ODP consolidation and that sleep promotes translation (but not transcription) of proteins essential for synaptic plasticity (i.e., ARC and BDNF). Our study thus reveals a previously unknown mechanism operating during sleep that consolidates cortical plasticity in vivo