Sleep Stage Transitions and Sleep-Dependent Memory Consolidation in Children with Narcolepsy-Cataplexy.

Electroencephalographic sleep stage transitions and altered first REM sleep period transitions have been identified as biomarkers of type 1 narcolepsy in adults, but not in children. Studies on memory complaints in narcolepsy have not yet investigated sleep-dependent memory consolidation. We aimed to explore stage transitions; more specifically altered REM sleep transition and its relationship with sleep-dependent memory consolidation in children with narcolepsy. Twenty-one children with narcolepsy-cataplexy and twenty-three healthy control children completed overnight polysomnography and sleep-dependent memory consolidation tests. Overnight transition rates (number of transitions per hour), global relative transition frequencies (number of transitions between a stage and all other stages/total number of transitions × 100), overnight transitions to REM sleep (transition from a given stage to REM/total REM transitions × 100), and altered first REM sleep period transitions (transitions from wake or N1 to the first REM period) were computed. Narcoleptic children had a significantly higher overnight transition rate with a higher global relative transition frequencies to wake. A lower sleep-dependent memory consolidation score found in children with narcolepsy was associated with a higher overnight transition frequency. As observed in narcoleptic adults, 90.48% of narcoleptic children exhibited an altered first REM sleep transition. As in adults, the altered sleep stage transition is also present in children with narcolepsy-cataplexy, and a higher transition rate could have an impact on sleep-dependent memory consolidation. These potential biomarkers could help diagnose type 1 narcolepsy in children more quickly; however, further studies with larger cohorts, including of those with type 2 narcolepsy and hypersomnia, are needed.

A meta-analysis of the associations between insufficient sleep duration and antibody response to vaccination.

Vaccination is a major strategy to control a viral pandemic. Simple behavioral interventions that might boost vaccine responses have yet to be identified. We conducted meta-analyses to summarize the evidence linking the amount of sleep obtained in the days surrounding vaccination to antibody response in healthy adults. Authors of the included studies provided the information needed to accurately estimate the pooled effect size (ES) and 95% confidence intervals (95% CI) and to examine sex differences.1,2,3,4,5,6,7 The association between self-reported short sleep (<6 h/night) and reduced vaccine response did not reach our pre-defined statistical significant criteria (total n = 504, ages 18-85; overall ES [95% CI] = 0.29 [-0.04, 0.63]). Objectively assessed short sleep was associated with a robust decrease in antibody response (total n = 304, ages 18-60; overall ES [95% CI] = 0.79 [0.40, 1.18]). In men, the pooled ES was large (overall ES [95% CI] = 0.93 [0.54, 1.33]), whereas it did not reach significance in women (overall ES [95% CI] = 0.42 [-0.49, 1.32]). These results provide evidence that insufficient sleep duration substantially decreases the response to anti-viral vaccination and suggests that achieving adequate amount of sleep during the days surrounding vaccination may enhance and prolong the humoral response. Large-scale well-controlled studies are urgently needed to define (1) the window of time around inoculation when optimizing sleep duration is most beneficial, (2) the causes of the sex disparity in the impact of sleep on the response, and (3) the amount of sleep needed to protect the response.

Objective and Subjective Assessments of Sleep in Children: Comparison of Actigraphy, Sleep Diary Completed by Children and Parents' Estimation.

In research and clinical contexts, parents' report and sleep diary filled in by parents are often used to characterize sleep-wake rhythms in children. The current study aimed to investigate children self-perception of their sleep, by comparing sleep diaries filled in by themselves, actigraphic sleep recordings, and parental subjective estimation. Eighty children aged 8-9 years wore actigraph wristwatches and completed sleep diaries for 7 days, while their parents completed a sleep-schedule questionnaire about their child' sleep. The level of agreement and correlation between sleep parameters derived from these three methods were measured. Sleep parameters were considered for the whole week and school days and weekends separately and a comparison between children with high and low sleep efficiency was carried out. Compared to actigraphy, children overestimated their sleep duration by 92 min and demonstrated significant difficulty to assess the amount of time they spent awake during the night. The estimations were better in children with high sleep efficiency compared to those with low sleep efficiency. Parents estimated that their children went to bed 36 min earlier and obtained 36.5 min more sleep than objective estimations with actigraphy. Children and parents' accuracy to estimate sleep parameters was different during school days and weekends, supporting the importance of analyzing separately school days and weekends when measuring sleep in children. Actigraphy and sleep diaries showed good agreement for bedtime and wake-up time, but not for SOL and WASO. A satisfactory agreement for TST was observed during school days only, but not during weekends. Even if parents provided more accurate sleep estimation than children, parents' report, and actigraphic data were weakly correlated and levels of agreement were insufficient. These results suggested that sleep diary completed by children provides interesting measures of self-perception, while actigraphy may provide additional information about nocturnal wake times. Sleep diary associated with actigraphy could be an interesting tool to evaluate parameters that could contribute to adjust subjective perception to objective sleep values.

Visual and auditory perceptual strength norms for 3,596 French nouns and their relationship with other psycholinguistic variables.

Perceptual experience plays a critical role in the conceptual representation of words. Higher levels of semantic variables such as imageability, concreteness, and sensory experience are generally associated with faster and more accurate word processing. Nevertheless, these variables tend to be assessed mostly on the basis of visual experience. This underestimates the potential contributions of other perceptual modalities. Accordingly, recent evidence has stressed the importance of providing modality-specific perceptual strength norms. In the present study, we developed French Canadian norms of visual and auditory perceptual strength (i.e., the modalities that have major impact on word processing) for 3,596 nouns. We then explored the relationship between these newly developed variables and other lexical, orthographic, and semantic variables. Finally, we demonstrated the contributions of visual and auditory perceptual strength ratings to visual word processing beyond those of other semantic variables related to perceptual experience (e.g., concreteness, imageability, and sensory experience ratings). The ratings developed in this study are a meaningful contribution toward the implementation of new studies that will shed further light on the interaction between linguistic, semantic, and perceptual systems.

Norms of conceptual familiarity for 3,596 French nouns and their contribution in lexical decision.

In the last decade, research has shown that word processing is influenced by the lexical and semantic features of words. However, norms for a crucial semantic variable-that is, conceptual familiarity-have not been available for a sizeable French database. We thus developed French Canadian conceptual familiarity norms for 3,596 nouns. This enriches Desrochers and Thompson's (2009) database, in which subjective frequency and imageability values are already available for the same words. We collected online data from 313 Canadian French speakers. The full database of conceptual familiarity ratings is freely available at http://lingualab.ca/fr/projets/normes-de-familiarite-conceptuelle . We then demonstrated the utility of these new conceptual familiarity norms by assessing their contribution to lexical decision times. We conducted a stepwise regression model with conceptual familiarity in the last step. This allowed us to assess the independent contribution of conceptual familiarity beyond the contributions of other well-known psycholinguistic variables, such as frequency, imageability, and age of acquisition. The results showed that conceptual familiarity facilitated lexical decision latencies. In sum, these ratings will help researchers select French stimuli for experiments in which conceptual familiarity must be taken into account.

When a Reactivated Visual Mask Disrupts Serial Recall.

To prevent forgetting in working memory, the attentional refreshing is supposed to increase the level of activation of memory traces by focusing attention. However, the involvement of memory traces reactivation in refreshing relies in the majority on indirect evidence. The aim of this study was to show that refreshing relies on the reactivation of memory traces by investigating how the reactivation of an irrelevant trace prevents the attentional refreshing to take place, and (2) the memory traces reactivated are sensorial in nature. We used a reactivated visual mask presented during the encoding (Experiment 1) and the refreshing (Experiment 2) of pictures in a complex span task. Results showed impaired serial recall performance in both experiments when the mask was reactivated compared to a control stimulus. Experiment 3 confirmed the refreshing account of these results. We proposed that refreshing relies on the reactivation of sensory memory traces.

Sleep on your memory traces: How sleep effects can be explained by Act-In, a functional memory model.

Numerous studies have explored the effect of sleep on memory. It is well known that a period of sleep, compared to a similar period of wakefulness, protects memories from interference, improves performance, and might also reorganize memory traces in a way that encourages creativity and rule extraction. It is assumed that these benefits come from the reactivation of brain networks, mainly involving the hippocampal structure, as well as from their synchronization with neocortical networks during sleep, thereby underpinning sleep-dependent memory consolidation and reorganization. However, this memory reorganization is difficult to explain within classical memory models. The present paper aims to describe whether the influence of sleep on memory could be explained using a multiple trace memory model that is consistent with the concept of embodied cognition: the Act-In (activation-integration) memory model. We propose an original approach to the results observed in sleep research on the basis of two simple mechanisms, namely activation and integration.

Haptic modality takes its time: Dynamic of activations of sensory modalities in perceptual and memory processes.

Based on claims resulting from grounded cognition theory that perceptual and memory processes are using the same distributed systems, the present study investigated the temporal aspect of access to memory traces through haptic and auditory modalities. Unlike in the case of visual or auditory components, the perception of a vibrotactile component is more sequential in nature and therefore cannot be fully processed before the end of the signal. The present study explores the dynamic of components activation in a situation of audio-vibrotactile asynchrony. We used a short-term priming paradigm consisting of an association phase (between a vibration and sound) and a test phase testing priming effect of a vibrotactile stimulation on the processing of a target sound. Results showed an interference with a simultaneous processing and a facilitation with a sequential processing. The temporality process of perceptual components is also important at a memory level.

A comprehensive literature review of chronic pain and memory.

Chronic pain patients often complain of their "poor memory" and numerous studies objectively confirmed such difficulties in reporting working memory (WM) and long-term memory (LTM) dysfunctions. This paper provides a comprehensive review of the literature on memory impairment in chronic pain (CP) patients. Twenty-four observational studies evaluating WM or/and LTM in a chronic pain group and a control group were included in this review. Results showed that studies consistently reported a moderate decline, in both WM and LTM performances in CP patients. Even if CP patients complained about forgetfulness, objective measurements did not permit to conclude to a long-term storage impairment. CP patients exhibited more specifically encoding or retrieving difficulties compared to controls. Results showed that chronic pain selectively impacted the most attention-demanding memory processes, such as working memory and recollection in long-term memory. Results also demonstrated that CP patients exhibited a memory bias directed towards painful events compared to control subjects. Several authors have suggested that CP could be a maladaptive consequence of memory mechanisms. The long-lasting presence of pain continuously reinforces aversive emotional associations with incidental events. The inability to extinguish this painful memory trace could explain the chronic persistence of pain even when the original injury has disappeared. A major concern is the need to extricate pain-related cognitive effects from those resulting from all the co-morbidities associated with CP which both have a deleterious effect on cognitive function.

Pain dilates time perception.

We have all experienced that time seems stretched during unpleasant situations. While there is evidence of subjective time overestimation when perceiving external unpleasant stimuli, no study has measured the dilation of time when individuals experience an unpleasant situation in their own body. Here we measured the time dilation induced by a painful homeostatic deviance using temporal bisection task. We show that being in pain leads to an expansion of subjective time whereby a stronger increase in pain perception relative to non-painful stimulation leads to a stronger time-estimate distortion. Neurophysiological studies suggest that time estimation and the perception of self might share a common neural substrate. We propose that, along with bodily arousal and attentional capture, the enhancement of self-awareness may be critical to support dilated subjective time when experiencing pain. As other homeostatic deviances, pain may induce a focus on ourselves contributing to the impression that "time stands still".

The automatic visual simulation of words: A memory reactivated mask slows down conceptual access.

How do we represent the meaning of words? The present study assesses whether access to conceptual knowledge requires the reenactment of the sensory components of a concept. The reenactment-that is, simulation-was tested in a word categorisation task using an innovative masking paradigm. We hypothesised that a meaningless reactivated visual mask should interfere with the simulation of the visual dimension of concrete words. This assumption was tested in a paradigm in which participants were not aware of the link between the visual mask and the words to be processed. In the first phase, participants created a tone-visual mask or tone-control stimulus association. In the test phase, they categorised words that were presented with 1 of the tones. Results showed that words were processed more slowly when they were presented with the reactivated mask. This interference effect was only correlated with and explained by the value of the visual perceptual strength of the words (i.e., our experience with the visual dimensions associated with concepts) and not with other characteristics. We interpret these findings in terms of word access, which may involve the simulation of sensory features associated with the concept, even if participants were not explicitly required to access visual properties. (PsycINFO Database Record

The Reactivation of Motion influences Size Categorization in a Visuo-Haptic Illusion.

People simulate themselves moving when they view a picture, read a sentence, or simulate a situation that involves motion. The simulation of motion has often been studied in conceptual tasks such as language comprehension. However, most of these studies investigated the direct influence of motion simulation on tasks inducing motion. This article investigates whether a mo- tion induced by the reactivation of a dynamic picture can influence a task that did not require motion processing. In a first phase, a dynamic picture and a static picture were systematically presented with a vibrotactile stimulus (high or low frequency). The second phase of the experiment used a priming paradigm in which a vibrotactile stimulus was presented alone and followed by pictures of objects. Participants had to categorize objects as large or small relative to their typical size (simulated size). Results showed that when the target object was preceded by the vibrotactile stimulus previously associated with the dynamic picture, participants perceived all the objects as larger and categorized them more quickly when the objects were typically "large" and more slowly when the objects were typically "small." In light of embodied cognition theories, this bias in participants' perception is assumed to be caused by an induced forward motion. generated by the reactivated dynamic picture, which affects simulation of the size of the objects.

Memory plays tricks on me: perceptual bias induced by memory reactivated size in Ebbinghaus illusion.

The relationship between perceptual and memory processing is at the core of cognition. Growing evidence suggests reciprocal influences between them so that memory features should lead to an actual perceptual bias. In the present study, we investigate the reciprocal influence of perceptual and memory processing by further adapting the Ebbinghaus illusion and tested it in a psychophysical design. In a 2AFC (two-alternative forced choice) paradigm, the perceptual bias in the Ebbinghaus illusion was induced by a physical size (Experiment 1) or a memory reactivated size of the inducers (Experiment 2, the size was reactivated thanks to a color-size association). One test disk was presented on the left of the screen and was surrounded by six inducers with a large or small (perceptual or reactivated) size. The test disk varied in size and participants were asked to indicate whether this test disk was smaller or larger than a reference disk presented on the right of the screen (the reference disk was invariant in size). Participants' responses were influenced by the size of the inducers for the perceptual and the reactivated size of the inducers. These results provide new evidence for the influence of memory on perception in a psychophysics paradigm.

Manipulation gesture effect in visual and auditory presentations: the link between tools in perceptual and motor tasks.

There is much behavioral and neurophysiological evidence in support of the idea that seeing a tool activates motor components of action related to the perceived object (e.g., grasping, use manipulation). However, the question remains as to whether the processing of the motor components associated with the tool is automatic or depends on the situation, including the task and the modality of tool presentation. The present study investigated whether the activation of motor components involved in tool use in response to the simple perception of a tool is influenced by the link between prime and target tools, as well as by the modality of presentation, in perceptual or motor tasks. To explore this issue, we manipulated the similarity of gesture involved in the use of the prime and target (identical, similar, different) with two tool presentation modalities of the presentation tool (visual or auditory) in perceptual and motor tasks. Across the experiments, we also manipulated the relevance of the prime (i.e., associated or not with the current task). The participants saw a first tool (or heard the sound it makes), which was immediately followed by a second tool on which they had to perform a perceptual task (i.e., indicate whether the second tool was identical to or different from the first tool) or a motor task (i.e., manipulate the second tool as if it were the first tool). In both tasks, the similarity between the gestures employed for the first and the second tool was manipulated (Identical, Similar or Different gestures). The results showed that responses were faster when the manipulation gestures for the two tools were identical or similar, but only in the motor task. This effect was observed irrespective of the modality of presentation of the first tool, i.e., visual or auditory. We suggest that the influence of manipulation gesture on response time depends on the relevance of the first tool in motor tasks. We discuss these motor activation results in terms of the relevance and demands of the tasks.

Perceptual processing affects the reactivation of a sensory dimension during a categorization task.

According to grounded theories of cognition, knowledge is grounded in its sensory-motor features. Therefore, perceptual and conceptual processing should be based on the same distributed system so that conceptual and perceptual processes should interact. The present study assesses whether gustatory stimulation (participants tasted a sweet or a nonsweet yoghurt) could influence performance on a categorization task that involves the reactivation of the same sensory dimension. The results indicate that participants were slower (Experiment 1) or faster (Experiment 2), respectively, at categorizing pictures as representing edible sweet stimuli when they either simultaneously or had previously tasted a sweet yoghurt as compared to a nonsweet yoghurt. These results confirm the significant overlap between perceptual and memory mechanisms and suggest the functional equivalence between perceptually present and perceptually absent (memory reactivated) dimensions.