Géraldine Rauchs | Université de Caen Normandie (original) (raw)

Papers by Géraldine Rauchs

Journal of Clinical Medicine

Alcohol Use Disorder (AUD) results in sleep disturbances that may have deleterious impacts on cog... more Alcohol Use Disorder (AUD) results in sleep disturbances that may have deleterious impacts on cognition, especially on memory. However, little is known about the sleep architecture in patients with Korsakoff’s syndrome (KS). This study aims at characterizing sleep disturbances in KS compared to AUD without KS and at specifying the relationships with cognitive impairments. Twenty-nine AUD patients (22 without KS and 7 with KS) and 15 healthy controls underwent a neuropsychological assessment and a polysomnography. The severity of sleep-disordered breathing and sleep fragmentation was similar in AUD and KS patients compared to controls. Sleep architecture differed between both patient groups: the proportion of slow-wave sleep was reduced in AUD patients only, while a lower proportion of rapid-eye movement (REM) sleep was specifically observed in KS patients. The proportion of REM sleep correlated with the severity of episodic memory deficits when AUD and KS were examined together. The...

Alzheimer's & Dementia: Translational Research & Clinical Interventions, 2018

Introduction: The Age-Well observational, cross-sectional study investigates the affective and co... more Introduction: The Age-Well observational, cross-sectional study investigates the affective and cognitive mechanisms of meditation expertise with behavioral, neuroimaging, sleep, and biological measures sensitive to aging and Alzheimer's disease (AD). Methods: Thirty cognitively unimpaired individuals aged 65 years or older with at least 10,000 hours of practice in mindfulness meditation (MM) and loving-kindness and compassion meditation (LKCM) are selected. The outcomes are the neuroimaging brain correlates of MM and LKCM and the assessments of long-term meditation practices on behavioral, neural, and biological measures as compared to nonmeditator older controls from the Age-Well randomized controlled trial. Results: Recruitment and data collection began in late 2016 and will be completed by late 2019. Discussion: Results are expected to foster the understanding of the effects of meditation expertise on aging and of the mechanisms of action underlying the meditation intervention in the Age-Well randomized controlled trial. These finding will contribute to the design of meditation-based prevention randomized controlled trials for the aged population and to the exploration of the possible long-time developmental trajectory of meditation training.

Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring, 2019

Introduction: Sleep disturbances are increasingly recognized as a risk factor for Alzheimer's dis... more Introduction: Sleep disturbances are increasingly recognized as a risk factor for Alzheimer's disease (AD). However, no study has assessed the relationships between objective sleep fragmentation (SF), brain and cognitive integrity across different cognitive stages, from cognitively unimpaired elderly subjects to patients with Subjective Cognitive Decline (SCD) and/or Mild Cognitive Impairment (MCI). Methods: 30 cognitively unimpaired elderly participants and 36 SCD/MCI patients underwent a neuropsychological evaluation, structural MRI, 18 F-fluorodeoxyglucose and 18 F-Florbetapir PET scans, and an actigraphy recording over a minimum of six consecutive nights. Multiple regression and mediation analyses were performed between SF parameters, neuroimaging data, and cognitive scores. Results: In cognitively unimpaired elderly participants, SF intensity mediated the association between fronto-hippocampal hypometabolism and lower executive functioning. Moreover, to a lower extent, increased SF variability was related to thalamic atrophy and ventromedial prefrontal amyloid burden. However, in SCD/MCI patients, SF no longer contributed to the expression of cognitive deficits. Discussion: These findings suggest that SF may directly contribute to lower cognitive performance in cognitively unimpaired elderly subjects. Therefore, treating sleep disturbances before the onset of cognitive deficits may help to cope with brain alterations and maintain cognitive functioning.

How aging affects sleep-dependent memory consolidation?

NeuroImage, 2021

Many genes have been identified manipulation of which can alter lifespan in the nematode Caenorha... more Many genes have been identified manipulation of which can alter lifespan in the nematode Caenorhabditis elegans. By comparison, the proximate mechanisms that such genes influence to alter lifespan remain poorly understood. Lifespan is a function of senescent pathology that causes death (Blagosklonny, 2007; Gems, 2015). In C. elegans, a subset of aging wild-type hermaphrodites die as the result of a lethal pharyngeal infection (Zhao et al., 2017). This is detectable by means of necropsy after death from old age, as corpses with an enlarged, swollen pharynx (P death ["big P"]). Worms that escape P death die later with an atrophied pharynx (p death ["small p"]) (Figure 1a). Genetic mutations or treatments that change lifespan act by differentially altering the frequency and/or timing of

Clocks & Sleep, 2019

Prospective memory (PM) refers to our ability to perform actions at the appropriate moment, eithe... more Prospective memory (PM) refers to our ability to perform actions at the appropriate moment, either when a predetermined event occurs (event-based, EB) or after a predetermined amount of time (time-based, TB). Sleep favors the consolidation of both EB and TB intentions, but whether this benefit is preserved during ageing is still subject to debate. PM was assessed in 28 young and 27 older healthy volunteers using a virtual environment. Participants had to learn and execute intentions after intervals filled with either daytime wakefulness or nighttime sleep. Intentions consisted of four TB, four EB with a strong link between the cue triggering retrieval and the action to be performed (EB-link) and four with no link (EB-nolink). PM was not affected by age, whatever the type of intention and the nature of the retention interval. While sleep reinforced all types of intentions in young participants, this benefit was only observed for TB and EB-link intentions in older adults. Sleep also r...

BMC cancer, Jan 3, 2018

Breast cancer (BC) is the most frequent cancer in women with more than 70% of BC patients being t... more Breast cancer (BC) is the most frequent cancer in women with more than 70% of BC patients being treated with hormonal therapy (HT). Among these patients, some report difficulties in remembering what they are supposed to do at the right moment, referring to prospective memory (PM). PM is essential for autonomy and medical adherence of patients, and requires an ecological assessment. Virtual reality, that recreates naturalistic environment, seems to be a promising method to evaluate PM. Several BC patients also report sleep disturbances. Given the role of sleep on memory consolidation, it is imperative to explore the influence of sleep quality on PM in BC patients treated with HT. The purpose of PROSOM-K study is to assess PM functioning using virtual reality and sleep quality in BC treated or not with HT. PROSOM-K is a prospective study including post-menopausal BC patients ≤70 years old treated with radiotherapy (n = 25) or with radiotherapy and HT (n = 25), and healthy post-menopau...

Sleep, 2004

Study objectives: The aim of this study is to examine the effects of sleep deprivation during the... more Study objectives: The aim of this study is to examine the effects of sleep deprivation during the first or second half of the night on episodic memory consolidation. Episodic memory is defined as memory for events located in time and space. It is also characterized by autonoetic consciousness, which gives a subject the conscious sensation of traveling back in time to relive the original event and forward into the future. Design: Consolidation of episodic information was tested after 4-hour retention intervals, which followed learning and occurred during either the early or late half night, respectively dominated by slow wave sleep (SWS) or rapid eye movement (REM) sleep, or corresponding periods of wakefulness. Setting: Data collection occurred in the sleep laboratory. Participants: Forty-three young healthy subjects: 9 men and 34 women, age ranging from 18 to 26 years (mean 20.18 ± 1.94 years) were included in this study. Interventions: Waking after a 4-hour retention interval filled with early or late sleep, or 4-hour sleep deprivation, during early or late period of night. Measurements and Results: The cognitive task, named the What-Where-When test, was specially designed to assess factual, spatial, and temporal components of episodic memory. This task was associated with the Remember/Know paradigm to assess autonoetic consciousness. We measured performance on immediate free recall, delayed free recall (after a 4-hour interval of wakefulness or sleep), and delayed recognition. We also calculated a forgetting rate for each feature (factual, spatial, and temporal) and, for the recognition task, scores of autonoetic consciousness (R responses). REM-sleep deprivation was associated with significantly lower recall of spatial information compared to SWS deprivation (P < .01) or late sleep (P < .05) conditions. REM-sleep deprivation was also associated with a higher forgetting rate of temporal information as compared to the early sleep condition (P < .01). Finally, REM-sleep deprivation led subjects to give significantly fewer R responses, indicative of true memories, as compared to SWS deprivation (P < .05). Conclusions: These results suggest that consolidation of truly episodic memories mainly involves REM sleep.

Cortex, 2016

The self-reference effect (SRE) has been shown to benefit episodic memory in healthy individuals.... more The self-reference effect (SRE) has been shown to benefit episodic memory in healthy individuals. In healthy aging, its preservation is acknowledged, but in Alzheimer's disease (AD), the jury is still out. Furthermore, there has yet to be a study of the SRE in amnesticmild cognitive impairment (aMCI). As self-reference implies subjective self-representations, and positive information enhance memory performance, weset out to examine the effects of 1) material and 2) identity valence on the SRE across the early stages of AD. Twenty healthy older individuals and 40 patients (20 diagnosed withaMCI and 20 diagnosedwith mild AD) performed a memory task. Participants had to judge positive and negative personality trait adjectiveswith reference to themselvesor to anotherperson, or elseprocess these adjectives semantically. We then administered a recognition task. Participants also completed a questionnaire on identity valence. Among healthy older individuals, the SRE benefited episodic memory independentlyof materialand identity valence. By contrast, among aMCI patients,we only observed the SRE when the material was positive. When self-referential material was negative, patients'performancedepended on the valence of their selfrepresentations: negative self-representations correlated with poor recognition of negative self-referentialadjectives. Finally, performance of patients with mild AD by condition and material valence were too low and inappropriate to be subjected to relevant analyses.The persistence of anSRE for positive adjectivesin aMCI suggests theexistence of a positivity effect for self-related information, which contributes to wellbeing. The absence of an SRE for negative adjectives,which led aMCI patients to dismiss negative self-related information, could be due to low self-esteem. These results corroborate the mnenic neglect model andpoint outthe importance of the psychoaffective dimension in patients with aMCI, which couldconstitute a major factor for the preservation of their self-esteem and selfrelatedmemory.

NeuroReport, 2008

Aging and Alzheimer s disease (AD) are both characterized by memory impairments and sleep changes... more Aging and Alzheimer s disease (AD) are both characterized by memory impairments and sleep changes. We investigated the potential ' link between these disturbances, focusing on sleep spindles, involved in memory consolidation. Two episodic memory tasks were given to young and old healthy subjects, as well as to AD patients. Post-learning sleep was recorded. Sleep spindles were globally reduced in aging and AD. AD patients also exhibited a further decrease in fast spindles. Besides, mean intensity of fast spindles was positively correlated, in AD patients, with immediate recall performance. Our results are the first report of a specific decrease in fast spindles in AD, associated with learning abilities. They also give further hints for a functional differentiation between slow and fast spindles.

Hippocampus, 2008

Finding our way in a previously learned, ecologically valid environment concurrently involves spa... more Finding our way in a previously learned, ecologically valid environment concurrently involves spatial and contextual cognitive operations. The former process accesses a cognitive map representing the spatial interactions between all paths in the environment. The latter accesses stored associations between landmark objects and their milieu. Here, we aimed at dissociating their neural basis in the context of memory-based virtual navigation. To do so, subjects freely explored a virtual town for 1 h, then were scanned using fMRI while retrieving their way between two locations, under four navigation conditions designed to probe separately or jointly the spatial and contextual memory components. Besides prominent commonalities found in a large hippocamponeocortical network classically involved in topographical navigation, results yield evidence for a partial dissociation between the brain areas supporting spatial and contextual components of memory-based navigation. Performance-related analyses indicate that hippocampal activity mostly supports the spatial component, whereas parahippocampal activity primarily supports the contextual component. Additionally, the recruitment of contextual memory during navigation was associated with higher frontal, posterior parietal and lateral temporal activity. These results provide evidence for a partial segregation of the neural substrates of two crucial memory components in human navigation, whose combined involvement eventually leads to efficient navigation behavior within a learned environment. V

Proceedings of the National Academy of Sciences, 2007

In humans, some evidence suggests that there are two different types of spindles during sleep, wh... more In humans, some evidence suggests that there are two different types of spindles during sleep, which differ by their scalp topography and possibly some aspects of their regulation. To test for the existence of two different spindle types, we characterized the activity associated with slow (11–13 Hz) and fast (13–15 Hz) spindles, identified as discrete events during non-rapid eye movement sleep, in non-sleep-deprived human volunteers, using simultaneous electroencephalography and functional MRI. An activation pattern common to both spindle types involved the thalami, paralimbic areas (anterior cingulate and insular cortices), and superior temporal gyri. No thalamic difference was detected in the direct comparison between slow and fast spindles although some thalamic areas were preferentially activated in relation to either spindle type. Beyond the common activation pattern, the increases in cortical activity differed significantly between the two spindle types. Slow spindles were ass...

PLoS ONE, 2012

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

PLoS ONE, 2010

The development of musical skills by musicians results in specific structural and functional modi... more 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.

PLoS ONE, 2014

Information that is processed with reference to oneself, i.e. Self-Referential Processing (SRP), ... more Information that is processed with reference to oneself, i.e. Self-Referential Processing (SRP), is generally associated with better remembering compared to information processed in a condition not related to oneself. This positive effect of the self on subsequent memory performance is called as Self-Reference Effect (SRE). The neural basis of SRE is still poorly understood. The main goal of the present work was thus to highlight brain changes associated with SRE in terms of activity and functional coupling and during both encoding and retrieval so as to assess the relative contribution of both processes to SRE. For this purpose, we used an fMRI event-related self-referential paradigm in 30 healthy young subjects and measured brain activity during both encoding and retrieval of self-relevant information compared to a semantic control condition. We found that SRE was associated with brain changes during the encoding phase only, including both greater activity in the medial prefrontal cortex and hippocampus, and greater functional coupling between these brain regions and the posterior cingulate cortex. These findings highlight the contribution of brain regions involved in both SRP and episodic memory and the relevance of the communication between these regions during the encoding process as the neural substrates of SRE. This is consistent with the idea that SRE reflects a positive effect of the reactivation of self-related memories on the encoding of new information in episodic memory.

PLoS ONE, 2007

Background. Relatively long duration retinal light exposure elicits nonvisual responses in humans... more 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.

NeuroImage, 2012

During the initial training of a motor sequence, performance becomes progressively faster but als... more During the initial training of a motor sequence, performance becomes progressively faster but also increasingly reproducible and consistent. However, performance temporarily becomes more variable at mid-training, reflecting a change in the motor representation and the eventual selection of the optimal performance mode (Adi-Japha et al., 2008). At the cerebral level, whereas performance speed is known to be related to the activity in cerebellocortical and striato-cortical networks, the neural correlates of performance variability remain unknown. We characterized the latter using functional magnetic resonance imaging (fMRI) during the initial training to the Finger Tapping Task (FTT), during which participants produced a 5-element finger sequence on a keyboard with their left non-dominant hand. Our results show that responses in the precuneus decrease whereas responses in the caudate nucleus increase as performance becomes more consistent. In addition, a variable performance is associated with enhanced interaction between the hippocampus and fronto-parietal areas and between the striatum and frontal areas. Our results suggest that these dynamic large-scale interactions represent a cornerstone in the implementation of consistent motor behavior in humans.

Frontiers in Neurology, 2013

Amyloid-beta dynamics are regulated by orexin and the sleep-wake cycle.

Frontiers in Neurology, 2012

Memories are not stored as they were initially encoded but rather undergo a gradual reorganizatio... more 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.