Gaétane Deliens | Université libre de Bruxelles (original) (raw)

Papers by Gaétane Deliens

Objectives: The aim of this study was to assess the prevalence of potentially inappropriate medic... more Objectives: The aim of this study was to assess the prevalence of potentially inappropriate medication (PIM) use upon admission and at discharge in a geriatric oncology unit after involving a clinical pharmacist. Although the few studies conducted in geriatric oncology units used the 2003 Beers criteria, this study used START and STOPP criteria, a more appropriate tool for European formularies. Materials and methods: Prospective study in older (≥70 years) patients consecutively admitted to a geriatric oncology unit in a cancer center from July 2011 to April 2012. Clinical pharmacist conducted a complete comprehensive medication review including non-prescription and complementary (herbals) medications. This information coupled with the patient's medical history allows identifying PIMs using the STOPP and START criteria. The number of PIMs at admission and at discharge from the hospital was compared after clinical pharmacist intervention. Results: Ninety-one older cancer patients (mean age ± SD = 79 ± 6 years) were included in the study. START criteria identified 41 PIMs for 31 persons (34%) at admission compared to 7 PIMs for 6 persons (7%) at discharge. STOPP criteria identified 50 PIMs at admission for 29 persons (32%) compared to 16 PIMs at discharge for 14 persons (16%). Results showed significantly lower START scores at discharge than at admission (p < 0.001); similarly, STOPP criteria demonstrated fewer PIMs at discharge than at admission (p < 0.001). Conclusion: The use of START and STOPP criteria by a clinical pharmacist allows identifying PIMs and changing prescriptions for older cancer patients in agreement with the oncologist and geriatrician of the team.

Objective: Declarative memory is consolidated during sleep in healthy children. We tested the hyp... more Objective: Declarative memory is consolidated during sleep in healthy children. We tested the hypothesis that consolidation processes are impaired in idiopathic focal epilepsies (IFE) of childhood in association with frequent interictal epileptiform discharges (IEDs) during sleep. Methods: A verbal (word-pair association) and a nonverbal (2D object location) declarative memory task were administrated to 15 children with IFEs and 8 control children 6–12 years of age. Patients had either centrotemporal (11 patients) or occipital (4 patients) IEDs. All but 3 patients had a history of unprovoked seizures, and 6 of them were treated with valproate (VPA). The learning procedure (location of object pairs presented on a grid; association of word pairs) was executed in the evening. Retrieval was tested immediately after learning and on the next morning after a night of sleep. Participants were tested twice, once in natural home conditions and one month later in the unfamiliar conditions of the sleep unit under EEG monitoring. Results: Overnight recall performance was lower in children with IFE than in control children on both tasks (ps b 0.05). Performance in home conditions was similar to that in hospital conditions. Higher spike–wave index (SWI) during nonrapid eye movement (NREM) sleep was associated with poorer performance in the non-verbal task (p b 0.05). Valproate treatment was not associated with overnight recall performance for both tasks (ps N 0.05). Conclusion: Memory consolidation is impaired in IFE of childhood. The association between higher SWI during NREM sleep and poorer nonverbal declarative memory consolidation supports the hypothesis that interictal epileptic activity could disrupt sleep memory consolidation.

SUMMARY Sleep deprivation is known to exert detrimental effects on various cognitive domains, inc... more SUMMARY Sleep deprivation is known to exert detrimental effects on various cognitive domains, including attention, vigilance and working memory. Seemingly at odds with these findings, prior studies repeatedly failed to evidence an impact of prior sleep deprivation on cognitive interference in the Stroop test, a hallmark paradigm in the study of cognitive control abilities. The present study investigated further the effect of sleep deprivation on cognitive control using an adapted version of the Stroop test that allows to segregate top–down (attentional reconfiguration on incongruent items) and bottom–up (facilitated processing after repetitions in responses and/or features of stimuli) components of performance. Participants underwent a regular night of sleep or a night of total sleep deprivation before cognitive testing. Results disclosed that sleep deprivation selectively impairs top–down adaptation mechanisms: cognitive control no longer increased upon detection of response conflict at the preceding trial. In parallel, bottom–up abilities were found unaffected by sleep deprivation: beneficial effects of stimulus and response repetitions persisted. Changes in vigilance states due to sleep deprivation selectively impact on cognitive control in the Stroop test by affecting top–down, but not bottom–up, mechanisms that guide adaptive behaviours.

Sleep problems have been commonly reported in children with autism spectrum disorder (ASD). This ... more Sleep problems have been commonly reported in children with autism spectrum disorder (ASD). This review takes a lifespan perspective in discussing recent findings on sleep disturbances in ASD, including sparse but pivotal studies in toddlers and adults. Current evidence shows that more than a mere comorbidity, sleep disturbances can represent a key factor in ASD. Already present before the age of 2, sleep problems are one of the early warning signs of ASD, which persist through lifespan. Genetic, epigenetic, psychological, and social/environmental factors involved in sleep disturbances in ASD contribute to better understand the core symptoms of autism (restricted and repetitive behaviors, communication , and social deficits). Although often considered as secondary by the therapeutic community, behavioral and pharmacological sleep interventions are efficient to reduce symptoms severity in ASD individuals and improve parents' mental health. This review should convince the scientific and medical community to address sleep complaints and autism symptoms together rather than separate entities.

There is growing evidence that sleep plays a pivotal role on health, cognition and emotional regu... more There is growing evidence that sleep plays a pivotal role on health, cognition and emotional regulation. However, the interplay between sleep and social cognition remains an uncharted research area. In particular, little is known about the impact of sleep deprivation on sarcasm detection, an ability which, once altered, may hamper everyday social interactions. The aim of this study is to determine whether sleep-deprived participants are as able as sleep-rested participants to adopt another perspective in gauging sarcastic statements. At 9am, after a whole night of sleep (n = 15) or a sleep deprivation night (n = 15), participants had to read the description of an event happening to a group of friends. An ambiguous voi-cemail message left by one of the friends on another's phone was then presented, and participants had to decide whether the recipient would perceive the message as sincere or as sarcastic. Messages were uttered with a neutral intonation and were either: (1) sarcastic from both the participant's and the addressee's perspectives (i.e. both had access to the relevant background knowledge to gauge the message as sarcastic), (2) sarcastic from the participant's but not from the addressee's perspective (i.e. the addressee lacked context knowledge to detect sarcasm) or (3) sincere. A fourth category consisted in messages sarcastic from both the participant's and from the addressee's perspective, uttered with a sarcastic tone. Although sleep-deprived participants were as accurate as sleep-rested participants in interpreting the voice message, they were also slower. Blunted reaction time was not fully explained by generalized cognitive slowing after sleep deprivation; rather, it could reflect a compensatory mechanism supporting normative accuracy level in sarcasm understanding. Introducing prosodic cues compensated for increased processing difficulties in sarcasm detection after sleep deprivation. Our findings support the hypothesis that sleep deprivation might damage the flow of social interactions by slowing perspective-taking processes.

Emerging evidence suggests that emotion and affect modulate the relation between sleep and cognit... more Emerging evidence suggests that emotion and affect modulate the relation between sleep and cognition. In the present study, we investigated the role of rapid-eye movement (REM) sleep in mood regulation and memory consolidation for sad stories. In a counterbalanced design, participants (n = 24) listened to either a neutral or a sad story during two sessions, spaced one week apart. After listening to the story, half of the participants had a short (45 min) morning nap. The other half had a long (90 min) morning nap, richer in REM and N2 sleep. Story recall, mood evolution and changes in emotional response to the re-exposure to the story were assessed after the nap. Although recall performance was similar for sad and neutral stories irrespective of nap duration, sleep measures were correlated with recall performance in the sad story condition only. After the long nap, REM sleep density positively correlated with retrieval performance, while re-exposure to the sad story led to diminished mood and increased skin conductance levels. Our results suggest that REM sleep may not only be associated with the consolidation of intrinsically sad material, but also enhances mood reactivity, at least on the short term.

The ability to perform two tasks simultaneously has become increasingly important as attention-de... more The ability to perform two tasks simultaneously has become increasingly important as attention-demanding technologies have become more common in daily life. This type of allocation of attentional resources is commonly called ‘‘divided attention.’’ Because of the importance of divided attention in natural world settings, substantial efforts have been recently made to promote an integrated, realistic assessment of functional abilities in dual task paradigms. In this context, virtual reality methods appear to be a good solution. However, to date, there has been little discussion on the validity of such methods. Here,
we offer a comparative review of conventional tools used to assess divided attention and also of the first virtual reality studies (mostly from the field of road and pedestrian safety).
The ecological character of virtual environments leads to a better understanding of the influence of dual-task settings and makes it possible to clarify issues such as the utility of
hands-free phones. After discussing the theoretical and clinical contributions of these studies, we discuss the limits of virtual reality assessment, focusing in particular: (i) on the challenges associated with the lack of familiarity with new technological devices; (ii) on the validity of the ecological character of virtual environments; and (iii) on the question of whether the results obtained in a specific context can be generalized to all dual-task
situations typical of daily life. To overcome the limitations associated with virtual reality, we propose: (i) to include a standardized familiarization phase in assessment protocols so as to limit the interference caused by the use of new technologies; (ii) to systematically compare virtual reality performance with conventional tests or real-life tests; and (iii) to
design dual-task scenarios that are independent from the patient’s expertise on one of the two tasks. We conclude that virtual reality appears to constitute a useful tool when used in
combination with more conventional tests.

Neurophysiologie clinique = Clinical neurophysiology, Jan 15, 2015

We investigated effects of NREM and REM predominant sleep periods on sleepiness and psychomotor p... more We investigated effects of NREM and REM predominant sleep periods on sleepiness and psychomotor performances measured with visual analog scales and the psychomotor vigilance task, respectively. After one week of stable sleep-wake rhythms, 18 healthy sleepers slept 3hours of early sleep and 3hours of late sleep, under polysomnographic control, spaced by two hours of sustained wakefulness between sleep periods in a within subjects split-night, sleep interruption protocol. Power spectra analysis was applied for sleep EEG recordings and sleep phase-relative power proportions were computed for six different frequency bands (delta, theta, alpha, sigma, beta and gamma). Both sleep periods presented with similar sleep duration and efficiency. As expected, phasic NREM and REM predominances were obtained for early and late sleep conditions, respectively. Albeit revealing additive effects of total sleep duration, our results showed a systematic discrepancy between psychomotor performances and ...

Beneficial effects of napping or bright light exposure on cognitive performance have been reporte... more Beneficial effects of napping or bright light exposure on cognitive performance have been reported in participants exposed to sleep loss. Nonetheless, few studies investigated the effect of these potential countermeasures against the temporary drop in performance observed in mid-afternoon, and even less so on cognitive flexibility, a crucial component of executive functions. This study investigated the impact of either an afternoon nap or bright light exposure on post-prandial alterations in task switching performance in well-rested participants. Twenty-five healthy adults participated in two randomized experimental conditions, either wake versus nap (n=15), or bright light versus placebo (n=10). Participants were tested on a switching task three times (morning, post-lunch and late afternoon sessions). The interventions occurred prior to the post-lunch session. In the nap/wake condition, participants either stayed awake watching a 30-minute documentary or had the opportunity to take a nap for 30 minutes. In the bright light/placebo condition, participants watched a documentary under either bright blue light or dim orange light (placebo) for 30 minutes. The switch cost estimates cognitive flexibility and measures task-switching efficiency. Increased switch cost scores indicate higher difficulties to switch between tasks. In both control conditions (wake or placebo), accuracy switch-cost score increased post lunch. Both interventions (nap or bright light) elicited a decrease in accuracy switch-cost score post lunch, which was associated with diminished fatigue and decreased variability in vigilance. Additionally, there was a trend for a post-lunch benefit of bright light with a decreased latency switch-cost score. In the nap group, improvements in accuracy switch-cost score were associated with more NREM sleep stage N1. Thus, exposure to bright light during the post-lunch dip, a countermeasure easily applicable in daily life, results in similar beneficial effects as a short nap on performance in the cognitive flexibility domain with possible additional benefits on latency switch-cost scores.

Neurophysiologie clinique = Clinical neurophysiology, Jan 15, 2015

PLoS ONE, 2013

Previous studies have shown that newly encoded memories are more resistant to retroactive interfe... more Previous studies have shown that newly encoded memories are more resistant to retroactive interference when participants are allowed to sleep after learning the original material, suggesting a sleep-related strengthening of memories. In the present study, we investigated delayed, long-term effects of sleep vs. sleep deprivation (SD) on the first post-training night on memory consolidation and resistance to interference. On day 1, participants learned a list of unrelated word pairs (AB), either in the morning or in the evening, then spent the post-training night in a sleep or sleep deprivation condition, in a within-subject paradigm. On day 4, at the same time of day, they learned a novel list of word pairs (AC) in which 50% of the word pairs stemmed with the same word than in the AB list, resulting in retroactive interference. Participants had then to recall items from the AB list upon presentation of the ''A'' stem. Recall was marginally improved in the evening, as compared to the morning learning group. Most importantly, retroactive interference effects were found in the sleep evening group only, contrary to the hypothesis that sleep exerts a protective role against intrusion by novel but similar learning. We tentatively suggest that these results can be explained in the framework of the memory reconsolidation theory, stating that exposure to similar information sets back consolidated items in a labile form again sensitive to retroactive interference. In this context, sleep might not protect against interference but would promote an update of existing episodic memories while preventing saturation of the memory network due to the accumulation of dual traces.

Neuropsychologia, 2011

Pseudoneglect is a slight but consistent misplacement of attention toward the left visual field, ... more Pseudoneglect is a slight but consistent misplacement of attention toward the left visual field, commonly observed in young healthy subjects. This leftward attentional bias is thought to result from a right hemispheric dominance in visuospatial processing. Changes in endogenous levels of alertness may modulate attentional asymmetries and pseudoneglect in particular. In line with this hypothesis, it has been shown that sleep deprived shift-workers present a reversal of their attentional bias in a landmark (LDM) task (Manly, T., Dobler, V. B., Dodds, C. M., & George, M. A. (2005). Rightward shift in spatial awareness with declining alertness. Neuropsychologia, 43(12), 1721-1728). However, circadian disturbances and fatigue effects at the end of a shift work may have contributed to this reversal effect. In a first experiment, we show that sleep deprivation (SD) under controlled conditions does not markedly change the leftward bias, observable both at 21:00 and at 07:00 after SD. In a second experiment, we tested the hypothesis that a drastic reduction or inversion in the attentional bias would be present only when both the circadian drive for sleep propensity is maximal (i.e. around 05:00) and homeostatic sleep pressure is high. Thus participants were tested at 21:00 and under SD conditions at 05:00 and 09:00. Additionally, we used the greyscales (GS) task well-known to evidence a leftward bias in luminance judgments. Although results evidenced a consistent leftward bias both in the LDM and GS, we found a suppression of the leftward bias at the circadian nadir of alertness (05:00) after SD only for the GS, but not for the LDM. Noticeably, the leftward bias in the GS vanished at 05:00 after SD but reappeared at 09:00 despite continued SD, suggesting a predominant circadian influence on attentional asymmetries in the GS. Additionally, intersessions correlations evidenced a reproducible, consistent bias both in the LDM and GS, with no consistent relationship between the two tasks, suggesting independence of the neural networks subtending performance in LDM and GS. Overall, our results suggest that SD per se does not impede the leftward bias both in LDM and GS, whereas circadian-related variations in vigilance may impact attentional asymmetries in luminance judgments.

Behavioral and Brain Sciences, 2013

This article argues that rapid eye movement (REM) dreaming is elaborative encoding for episodic m... more This article argues that rapid eye movement (REM) dreaming is elaborative encoding for episodic memories. Elaborative encoding in REM can, at least partially, be understood through ancient art of memory (AAOM) principles: visualization, bizarre association, organization, narration, embodiment, and location. These principles render recent memories more distinctive through novel and meaningful association with emotionally salient, remote memories. The AAOM optimizes memory performance, suggesting that its principles may predict aspects of how episodic memory is configured in the brain. Integration and segregation are fundamental organizing principles in the cerebral cortex. Episodic memory networks interconnect profusely within the cortex, creating omnidirectional "landmark" junctions. Memories may be integrated at junctions but segregated along connecting network paths that meet at junctions. Episodic junctions may be instantiated during non-rapid eye movement (NREM) sleep after hippocampal associational function during REM dreams. Hippocampal association involves relating, binding, and integrating episodic memories into a mnemonic compositional whole. This often bizarre, composite image has not been present to the senses; it is not "real" because it hyperassociates several memories. During REM sleep, on the phenomenological level, this composite image is experienced as a dream scene. A dream scene may be instantiated as omnidirectional neocortical junction and retained by the hippocampus as an index. On episodic memory retrieval, an external stimulus (or an internal representation) is matched by the hippocampus against its indices. One or more indices then reference the relevant neocortical junctions from which episodic memories can be retrieved. Episodic junctions reach a processing (rather than conscious) level during normal wake to enable retrieval. If this hypothesis is correct, the stuff of dreams is the stuff of memory.

Cognition & Emotion, 2014

Neutral memories unbind from their emotional acquisition context when sleep is allowed the night ... more Neutral memories unbind from their emotional acquisition context when sleep is allowed the night after learning and testing takes place after two additional nights of sleep. However, mood-dependent memory (MDM) effects are not abolished after a restricted sleep episode mostly featuring non rapideye-movement (NREM) or rapid-eye-movement (REM) sleep. Here, we tested whether (1) one night of sleep featuring several NREM-REM sleep cycles is sufficient to suppress MDM effects and (2) a neutral mood is a sufficiently contrasting state to induce MDM effects, i.e. interfere with the recall of information learned in happy or sad states. Results disclosed MDM effects both in the postlearning sleep and wake conditions, with better recall in congruent than incongruent emotional contexts. Our findings suggest that the emotional unbinding needs several consecutive nights of sleep to be complete, and that even subtle mood changes are sufficient to produce MDM effects.

SLEEP, 2000

Scrima's Hypothesis Revisited-Deliens et al A positive contribution of post-learning sleep in the... more Scrima's Hypothesis Revisited-Deliens et al A positive contribution of post-learning sleep in the consolidation of new information in long-term memory is now widely recognized. 1-7 Beneficial effects of post-learning sleep have been highlighted for various memory systems, such as verbal declarative memory, 8,9 emotional memory, 10,11 or spatial learning, 12 and non-declarative motor procedural learning 13 or priming. 14 Like long-term memory, sleep is not a unitary process but comprises different subsystems. In humans, it is characterized by two prominent stages, rapid eye movement (REM) and non-rapid eye movement (NREM) sleep. NREM is further subdivided 17 into stage 1 (N1), stage 2 (N2) and slow wave sleep (SWS or N3). Sleep stages, like memory subsystems, are differentiable at neuroanatomical, neurophysiological, and behavioral levels. 3,18 Notwithstanding, how sleep stages specifically contribute to the consolidation of different memory types remains a matter of debate.

Epilepsy & Behavior, 2015

Objective: Declarative memory is consolidated during sleep in healthy children. We tested the hyp... more Objective: Declarative memory is consolidated during sleep in healthy children. We tested the hypothesis that consolidation processes are impaired in idiopathic focal epilepsies (IFE) of childhood in association with frequent interictal epileptiform discharges (IEDs) during sleep. Methods: A verbal (word-pair association) and a nonverbal (2D object location) declarative memory task were administrated to 15 children with IFEs and 8 control children 6-12 years of age. Patients had either centrotemporal (11 patients) or occipital (4 patients) IEDs. All but 3 patients had a history of unprovoked seizures, and 6 of them were treated with valproate (VPA). The learning procedure (location of object pairs presented on a grid; association of word pairs) was executed in the evening. Retrieval was tested immediately after learning and on the next morning after a night of sleep. Participants were tested twice, once in natural home conditions and one month later in the unfamiliar conditions of the sleep unit under EEG monitoring. Results: Overnight recall performance was lower in children with IFE than in control children on both tasks (ps b 0.05). Performance in home conditions was similar to that in hospital conditions. Higher spike-wave index (SWI) during nonrapid eye movement (NREM) sleep was associated with poorer performance in the nonverbal task (p b 0.05). Valproate treatment was not associated with overnight recall performance for both tasks (ps N 0.05). Conclusion: Memory consolidation is impaired in IFE of childhood. The association between higher SWI during NREM sleep and poorer nonverbal declarative memory consolidation supports the hypothesis that interictal epileptic activity could disrupt sleep memory consolidation.

Journal of Vision, 2014

Several studies suggest that sleep improves perceptual skills in the visual texture discriminatio... more Several studies suggest that sleep improves perceptual skills in the visual texture discrimination task (TDT). Here we report that besides consolidation, sleep also generalizes the learned perceptual abilities to the untrained eye. Healthy volunteers (n ¼ 32) were trained on the TDT, in which they had to discriminate between horizontal and vertical target textures briefly presented in the periphery of the visual field (left upper quadrant). After a 10-hr interval filled with either sleep or wakefulness, they were retested first on the trained eye in the trained quadrant and then on the untrained eye and quadrant. In line with prior findings, visual discrimination was globally higher after sleep than after wakefulness, as compared to performance levels at the end of training. Furthermore, discrimination performance was significantly improved only in the sleep condition for the untrained eye in the same quadrant, but also showed a trend to generalize to the untrained eye and untrained quadrant. Our results suggest that sleep-dependent perceptual skills continue developing at a later visual-process stage than the V1 area, where learning is not monocular anymore.

Experimental Brain Research, 2014

Neurophysiologie clinique = Clinical neurophysiology, Jan 15, 2015

PLoS ONE, 2013

Neuropsychologia, 2011

Behavioral and Brain Sciences, 2013

Cognition & Emotion, 2014

SLEEP, 2000

Epilepsy & Behavior, 2015

Objective: Declarative memory is consolidated during sleep in healthy children. We tested the hyp... more Objective: Declarative memory is consolidated during sleep in healthy children. We tested the hypothesis that consolidation processes are impaired in idiopathic focal epilepsies (IFE) of childhood in association with frequent interictal epileptiform discharges (IEDs) during sleep. Methods: A verbal (word-pair association) and a nonverbal (2D object location) declarative memory task were administrated to 15 children with IFEs and 8 control children 6-12 years of age. Patients had either centrotemporal (11 patients) or occipital (4 patients) IEDs. All but 3 patients had a history of unprovoked seizures, and 6 of them were treated with valproate (VPA). The learning procedure (location of object pairs presented on a grid; association of word pairs) was executed in the evening. Retrieval was tested immediately after learning and on the next morning after a night of sleep. Participants were tested twice, once in natural home conditions and one month later in the unfamiliar conditions of the sleep unit under EEG monitoring. Results: Overnight recall performance was lower in children with IFE than in control children on both tasks (ps b 0.05). Performance in home conditions was similar to that in hospital conditions. Higher spike-wave index (SWI) during nonrapid eye movement (NREM) sleep was associated with poorer performance in the nonverbal task (p b 0.05). Valproate treatment was not associated with overnight recall performance for both tasks (ps N 0.05). Conclusion: Memory consolidation is impaired in IFE of childhood. The association between higher SWI during NREM sleep and poorer nonverbal declarative memory consolidation supports the hypothesis that interictal epileptic activity could disrupt sleep memory consolidation.

Journal of Vision, 2014

Experimental Brain Research, 2014