How Aging Affects Sleep-Dependent Memory Consolidation?

Memories are not stored as they were initially encoded but rather undergo a gradual reorganization process, termed memory consolidation. Numerous data indicate that sleep plays a major role in this process, notably due to the specific neurochemical environment and the electrophysiological activity observed during the night. Two putative, probably not exclusive, models (“hippocampo-neocortical dialogue” and “synaptic homeostasis hypothesis”) have been proposed to explain the beneficial effect of sleep on memory processes. However, all data gathered until now emerged from studies conducted in young subjects. The investigation of the relationships between sleep and memory in older adults has sparked off little interest until recently. Though, aging is characterized by memory impairment, changes in sleep architecture, as well as brain and neurochemical alterations. All these elements suggest that sleep-dependent memory consolidation may be impaired or occurs differently in older adults. This review outlines the mechanisms governing sleep-dependent memory consolidation, and the crucial points of this complex process that may dysfunction and result in impaired memory consolidation in aging

Editorial: The impact of age-related changes in brain network organization and sleep on memory

peer reviewe

Effect of cognitive reserve on the association between slow wave sleep and cognition in community-dwelling older adults

Sleep, especially slow wave sleep (SWS), is essential for cognitive functioning and is reduced in aging. The impact of sleep quality on cognition is variable, especially in aging. Cognitive reserve (CR) may be an important modulator of these effects. We aimed at investigating this question to better identify individuals in whom sleep disturbances might have greater behavioral consequences. Polysomnography and neuropsychological assessments were performed in 135 cognitively intact older adults (mean age ± SD: 69.4 ± 3.8y) from the Age-Well randomized controlled trial (baseline data). Two measures of cognitive engagement throughout life were used as CR proxies. Linear regression analyses were performed between the proportion of SWS, and executive function and episodic memory composite scores. Then, interaction analyses between SWS and CR proxies on cognition were conducted to assess the possible impact of CR on these links. SWS was positively associated with episodic memory, but not with executive function. CR proxies modulated the associations between SWS and both executive and episodic memory performance. Specifically, individuals with higher CR were able to maintain cognitive performance despite low amounts of SWS. This study provides the first evidence that CR may protect against the deleterious effects of age-related sleep changes on cognition

Alzheimers Dement

Introduction: The Age-Well clinical trial is an ongoing monocentric, randomized, controlled trial aiming to assess an 18-month preventive meditation-based intervention directly targeting the attentional and emotional dimensions of aging to promote mental health and well-being in elderly people. Methods: One hundred thirty-seven cognitively unimpaired older adults are randomized to either an 18-month meditation-based intervention, a structurally matched foreign language training, or a passive control arm. The impact of the intervention and underlying mechanisms are assessed with detailed cognitive, behavioral, biological, neuroimaging and sleep examinations. Results: Recruitment began in late 2016 and ended in May 2018. The interventions are ongoing and will be completed by early 2020. Discussion: This is the first trial addressing the emotional and cognitive dimension of aging with a long-term nonpharmacological approach and using comprehensive assessments to investigate the mechanisms. Results are expected to foster the development of preventive strategies reducing the negative impact of mental conditions and disorders

Exposure to negative socio-emotional events induces sustained alteration of resting-state brain networks in older adults

Basic emotional functions seem well preserved in older adults. However, their reactivity to and recovery from socially negative events remain poorly characterized. To address this, we designed a ‘task–rest’ paradigm in which 182 participants from two independent experiments underwent functional magnetic resonance imaging while exposed to socio-emotional videos. Experiment 1 (N = 55) validated the task in young and older participants and unveiled age-dependent effects on brain activity and connectivity that predominated in resting periods after (rather than during) negative social scenes. Crucially, emotional elicitation potentiated subsequent resting-state connectivity between default mode network and amygdala exclusively in older adults. Experiment 2 replicated these results in a large older adult cohort (N = 127) and additionally showed that emotion-driven changes in posterior default mode network–amygdala connectivity were associated with anxiety, rumination and negative thoughts. These findings uncover the neural dynamics of empathy-related functions in older adults and help understand its relationship to poor social stress recovery

Effect of an 18-Month Meditation Training on Regional Brain Volume and Perfusion in Older Adults: The Age-Well Randomized Clinical Trial.

peer reviewedImportance: No lifestyle-based randomized clinical trial directly targets psychoaffective risk factors of dementia. Meditation practices recently emerged as a promising mental training exercise to foster brain health and reduce dementia risk. Objective: To investigate the effects of meditation training on brain integrity in older adults. Design, Setting, and Participants: Age-Well was a randomized, controlled superiority trial with blinded end point assessment. Community-dwelling cognitively unimpaired adults 65 years and older were enrolled between November 24, 2016, and March 5, 2018, in France. Participants were randomly assigned (1:1:1) to (1) an 18-month meditation-based training, (2) a structurally matched non-native language (English) training, or (3) no intervention arm. Analysis took place between December 2020 and October 2021. Interventions: Meditation and non-native language training included 2-hour weekly group sessions, practice of 20 minutes or longer daily at home, and 1-day intensive practices. Main Outcomes and Measures: Primary outcomes included volume and perfusion of anterior cingulate cortex (ACC) and insula. Main secondary outcomes included a global composite score capturing metacognitive, prosocial, and self-regulatory capacities and constituent subscores. Results: Among 137 participants (mean [SD] age, 69.4 [3.8] years; 83 [60.6%] female; 54 [39.4%] male) assigned to the meditation (n = 45), non-native language training (n = 46), or no intervention (n = 46) groups, all but 1 completed the trial. There were no differences in volume changes of ACC (0.01 [98.75% CI, -0.02 to 0.05]; P = .36) or insula (0.01 [98.75% CI, -0.02 to 0.03]; P = .58) between meditation and no intervention or non-native language training groups, respectively. Differences in perfusion changes did not reach statistical significance for meditation compared with no intervention in ACC (0.02 [98.75% CI, -0.01 to 0.05]; P = .06) or compared with non-native language training in insula (0.02 [98.75% CI, -0.01 to 0.05]; P = .09). Meditation was superior to non-native language training on 18-month changes in a global composite score capturing attention regulation, socioemotional, and self-knowledge capacities (Cohen d, 0.52 [95% CI, 0.19-0.85]; P = .002). Conclusions and Relevance: The study findings confirm the feasibility of meditation and non-native language training in elderly individuals, with high adherence and very low attrition. Findings also show positive behavioral effects of meditation that were not reflected on volume, and not significantly on perfusion, of target brain areas. Trial Registration: ClinicalTrials.gov Identifier: NCT02977819

Sleep-Related Hippocampo-Cortical Interplay during Emotional Memory Recollection

Emotional events are usually better remembered than neutral ones. This effect is mediated in part by a modulation of the hippocampus by the amygdala. Sleep plays a role in the consolidation of declarative memory. We examined the impact of sleep and lack of sleep on the consolidation of emotional (negative and positive) memories at the macroscopic systems level. Using functional MRI (fMRI), we compared the neural correlates of successful recollection by humans of emotional and neutral stimuli, 72 h after encoding, with or without total sleep deprivation during the first post-encoding night. In contrast to recollection of neutral and positive stimuli, which was deteriorated by sleep deprivation, similar recollection levels were achieved for negative stimuli in both groups. Successful recollection of emotional stimuli elicited larger responses in the hippocampus and various cortical areas, including the medial prefrontal cortex, in the sleep group than in the sleep deprived group. This effect was consistent across subjects for negative items but depended linearly on individual memory performance for positive items. In addition, the hippocampus and medial prefrontal cortex were functionally more connected during recollection of either negative or positive than neutral items, and more so in sleeping than in sleep-deprived subjects. In the sleep-deprived group, recollection of negative items elicited larger responses in the amygdala and an occipital area than in the sleep group. In contrast, no such difference in brain responses between groups was associated with recollection of positive stimuli. The results suggest that the emotional significance of memories influences their sleep-dependent systems-level consolidation. The recruitment of hippocampo-neocortical networks during recollection is enhanced after sleep and is hindered by sleep deprivation. After sleep deprivation, recollection of negative, potentially dangerous, memories recruits an alternate amygdalo-cortical network, which would keep track of emotional information despite sleep deprivation

Virtualia 2016. La réalité virtuelle au service de la recherche: Actes du séminaire organisé par le CIREVE à Caen (19 octobre 2016),

International audienceLe séminaire Virtualia est né en 2006 en même temps que le Centre Interdisciplinaire de Réalité Virtuelle (CIREVE) de l’Université de Caen Normandie. Son objectif est de permettre aux équipes associées au CIREVE d’exposer leurs méthodologies et les résultats de leurs travaux dans le domaine de la Réalité Virtuelle, tout en s’ouvrant à des communications extérieures. Il a connu quatre éditions de 2006 à 2009.2016 fut l’occasion de relancer VIRTUALIA et de concrétiser le partenariat avec les Universités de Rouen et du Havre dans le cadre de la COMUE. Une Structure Fédérative de Recherche « CIREVE » est en effet en cours de labellisation au sein de Normandie Université. 2016 est également une année importante car elle marque à la fois le dixième anniversaire du CIREVE et la finalisation d’une plate-forme de réalité virtuelle normande, unique en son genre sur le territoire français. Elle est composée d’une salle immersive quatre faces de 45 m2, équipée d’un tapis roulant particulièrement adapté pour l’analyse de la marche en temps réel (GRAIL de Motek Medical). Les calculateurs de cette salle immersive sont mutualisés avec un amphithéâtre attenant de 150 places, de manière que les expérimentations effectuées avec un sujet unique dans la salle immersive puissent être suivies par un auditoire nombreux (besoins de formation notamment). Les équipes utilisent le matériel au fur et à mesure des développements informatiques et de nouveaux protocoles d’expérimentation germent dans l’esprit des chercheurs qui voient dans la réalité virtuelle des possibilités de tests jamais atteintes.Une centaine de chercheurs utilise régulièrement le plateau technique CIREVE, dans des visées de recherche qui leur sont propres. Il est toutefois apparu qu’un certain nombre de problématiques concernaient toutes les disciplines et qu’une partie de la réflexion sur les mondes virtuels pouvait être mutualisée. Le séminaire VIRTUALIA permet d’offrir un espace de rencontre à ces chercheurs, issus d’horizons différents, pour discuter de l’utilisation de l’outil d’un point de vue épistémologique. Il est par exemple capital de s’interroger sur la notion de présence. Le sujet se comporte-il de la même façon dans l’environnement virtuel et dans le monde réel ? Les chemins de circulation choisis dans le modèle virtuel sont-ils les mêmes que ceux qui seraient empruntés en réalité ? Les conclusions établies dans le modèle virtuel sont-elles directement transposables à la réalité ? Un des enjeux du travail est d’évaluer la pertinence subjective des modèles virtuels, ce qui est capital avant de généraliser leur utilisation dans des actions de formation par exemple. L’utilisation d’une technologie n’est jamais complètement neutre. Dans le cadre des mondes virtuels, l’interaction de l’homme avec le monde de synthèse n’est possible qu’au travers de logiciels et d’interfaces matérielles. Il faut s’assurer que les processus cognitifs soient adéquats avant de s’interroger sur le résultat des simulations. Naturellement, le séminaire permet également à chaque discipline d’exposer les résultats des dernières recherches réalisées grâce à la réalité virtuelle.Les domaines scientifiques concernés par la réalité virtuelle sont multiples : les civilisations et les patrimoines culturels, la médecine, les neurosciences, la psychologie, les sciences du mouvement et du sport, l’ingénierie, l’informatique. L’Université de Caen Normandie étant pluridisciplinaire, le spectre des utilisations est très large. Elles se répartissent en trois axes principaux et un axe en émergence :LA REPRÉSENTATION : la réalité virtuelle permet de représenter et de visualiser, interactivement et en trois dimensions, des environnements disparus, dégradés, inaccessibles, ou des environnements futurs.Domaines concernés : civilisations, patrimoine, linguistique...L'EXPÉRIMENTATION : en permettant d'interagir en temps réel avec un monde numérique 3D, la réalité virtuelle offre de nouvelles perspectives d'expérimentations dans des environnements de plus en plus proches du réel et en même temps parfaitement contrôlables.Domaines concernés : santé, neuropsychologie, psychologie, activités physiques et sportives...LA CREATION ET LE DEVELOPPEMENT D’OUTILS : les informaticiens créent et testent des applications concernant les méthodes de navigation en monde virtuel, de restitution de la réalité.Domaine concerné : informatique.LA FORMATION (axe en émergence) : par la représentation de la connaissance, par les diverses possibilités d'expérimentation, la réalité virtuelle est un formidable outil de formation.Domaines concernés : sciences du langage, médecine, informatique (serious game, simulation...).Une partie importante de la réflexion développée lors du séminaire Virtualia 2016 a été consacrée aux enjeux sociétaux liés à la réalité virtuelle : notions de mémoire, d’apprentissage des gestes techniques, d’être humain « augmenté » etc. Les articles publiés attestent du savoir-faire, bien réel cette fois, que le CIREVE a acquis en termes de création de mondes virtuels pour représenter, expérimenter et former. La publication des actes du séminaire Virtualia vise à mettre en lumière des recherches particulièrement innovantes qui s’effectuent dans un cadre technologique exceptionnel.- S. Madeleine, Virtualia 2016. Introduction (et direction de l'édition)- J. Grieu, F. Lecroq, Th. Galinho, H. Boukachour, Environnements industriels virtualisés et processus d’apprentissage- Ph. Brunet, J. Dehut, Images 3D et humanités numériques : modélisation et restitution du geste théâtral- G. Lecouvey, J. Gonneaud, N. Legrand, G. Rauchs, F. Eustache, B. Desgranges, Réalité virtuelle et mémoire- N. Benguigui, C. Mandil, M. Mallek, L. Lejeune, R. Thouvarecq, Étude des liens entre perception et action dans des environnements virtuels- E.-G. Dupuy, A. Maneuvrier, E. Vlamynck, S. Besnard, B. Bienvenu, L.-M. Decker, Le syndrome d’Ehlers-Danlos type hypermobile : évolution des stratégies posturales en réponse à un programme de rééducation à visée somesthésique- C. Weismann-Arcache, Réalité virtuelle et humain augmenté : subjectivation, désubjectivation ?- L. Haddouk, Réalité psychique en visioconsultatio

When Music and Long-Term Memory Interact: Effects of Musical Expertise on Functional and Structural Plasticity in the Hippocampus

The development of musical skills by musicians results in specific structural and functional modifications in the brain. Surprisingly, no functional magnetic resonance imaging (fMRI) study has investigated the impact of musical training on brain function during long-term memory retrieval, a faculty particularly important in music. Thus, using fMRI, we examined for the first time this process during a musical familiarity task (i.e., semantic memory for music). Musical expertise induced supplementary activations in the hippocampus, medial frontal gyrus, and superior temporal areas on both sides, suggesting a constant interaction between episodic and semantic memory during this task in musicians. In addition, a voxel-based morphometry (VBM) investigation was performed within these areas and revealed that gray matter density of the hippocampus was higher in musicians than in nonmusicians. Our data indicate that musical expertise critically modifies long-term memory processes and induces structural and functional plasticity in the hippocampus

Brain Responses to Violet, Blue, and Green Monochromatic Light Exposures in Humans: Prominent Role of Blue Light and the Brainstem

BACKGROUND: Relatively long duration retinal light exposure elicits nonvisual responses in humans, including modulation of alertness and cognition. These responses are thought to be mediated in part by melanopsin-expressing retinal ganglion cells which are more sensitive to blue light than violet or green light. The contribution of the melanopsin system and the brain mechanisms involved in the establishment of such responses to light remain to be established. METHODOLOGY/PRINCIPAL FINDINGS: We exposed 15 participants to short duration (50 s) monochromatic violet (430 nm), blue (473 nm), and green (527 nm) light exposures of equal photon flux (10(13)ph/cm(2)/s) while they were performing a working memory task in fMRI. At light onset, blue light, as compared to green light, increased activity in the left hippocampus, left thalamus, and right amygdala. During the task, blue light, as compared to violet light, increased activity in the left middle frontal gyrus, left thalamus and a bilateral area of the brainstem consistent with activation of the locus coeruleus. CONCLUSION/SIGNIFICANCE: These results support a prominent contribution of melanopsin-expressing retinal ganglion cells to brain responses to light within the very first seconds of an exposure. The results also demonstrate the implication of the brainstem in mediating these responses in humans and speak for a broad involvement of light in the regulation of brain function