References of "Maquet, Pierre"
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See detailLa neuro-imagerie: au-delà des images, une modélisation du fonctionnement cérébral humain
Maquet, Pierre ULg

in Medecine sciences : M/S (2011), 27(1), 5-6

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See detailEffects of light on cognitive brain responses depend on circadian phase and sleep homeostasis.
Vandewalle, Gilles ULg; Archer, Simon N; Wuillaume, Catherine et al

in Journal of biological rhythms (2011), 26(3), 249-59

Light is a powerful modulator of cognition through its long-term effects on circadian rhythmicity and direct effects on brain function as identified by neuroimaging. How the direct impact of light on ... [more ▼]

Light is a powerful modulator of cognition through its long-term effects on circadian rhythmicity and direct effects on brain function as identified by neuroimaging. How the direct impact of light on brain function varies with wavelength of light, circadian phase, and sleep homeostasis, and how this differs between individuals, is a largely unexplored area. Using functional MRI, we compared the effects of 1 minute of low-intensity blue (473 nm) and green light (527 nm) exposures on brain responses to an auditory working memory task while varying circadian phase and status of the sleep homeostat. Data were collected in 27 subjects genotyped for the PER3 VNTR (12 PER3(5/5) and 15 PER3(4/4) ) in whom it was previously shown that the brain responses to this task, when conducted in darkness, depend on circadian phase, sleep homeostasis, and genotype. In the morning after sleep, blue light, relative to green light, increased brain responses primarily in the ventrolateral and dorsolateral prefrontal cortex and in the intraparietal sulcus, but only in PER3(4/4) individuals. By contrast, in the morning after sleep loss, blue light increased brain responses in a left thalamofrontoparietal circuit to a larger extent than green light, and only so in PER3(5/5) individuals. In the evening wake maintenance zone following a normal waking day, no differential effect of 1 minute of blue versus green light was observed in either genotype. Comparison of the current results with the findings observed in darkness indicates that light acts as an activating agent particularly under those circumstances in which and in those individuals in whom brain function is jeopardized by an adverse circadian phase and high homeostatic sleep pressure. [less ▲]

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See detailExperience-dependent induction of hypnagogic images during daytime naps: a combined behavioural and EEG study.
Kussé, Caroline ULg; Shaffii, Anahita ULg; Schrouff, Jessica ULg et al

in Journal of Sleep Research (2011)

This study characterizes hypnagogic hallucinations reported during a polygraphically recorded 90-min daytime nap following or preceding practice of the computer game Tetris. In the experimental group (N ... [more ▼]

This study characterizes hypnagogic hallucinations reported during a polygraphically recorded 90-min daytime nap following or preceding practice of the computer game Tetris. In the experimental group (N = 16), participants played Tetris in the morning for 2 h during three consecutive days, while in a first control group (N = 13, controlling the effect of experience) participants did not play any game, and in a second control group (N = 14, controlling the effect of anticipation) participants played Tetris after the nap. During afternoon naps, participants were repetitively awakened 15, 45, 75, 120 or 180 s after the onset of S1, and were asked to report their mental content. Reports content was scored by three judges (inter-rater reliability 85%). In the experimental group, 48 out of 485 (10%) sleep-onset reports were Tetris-related. They mostly consisted of images and sounds with very little emotional content. They exactly reproduced Tetris elements or mixed them with other mnemonic components. By contrast, in the first control group, only one report out of 107 was scored as Tetris-related (1%), and in the second control group only three reports out of 112 were scored as Tetris-related (3%; between-groups comparison; P = 0.006). Hypnagogic hallucinations were more consistently induced by experience than by anticipation (P = 0.039), and they were predominantly observed during the transition of wakefulness to sleep. The observed attributes of experience-related hypnagogic hallucinations are consistent with the particular organization of regional brain activity at sleep onset, characterized by high activity in sensory cortices and in the default-mode network. [less ▲]

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See detailIdentifying the default-mode component in spatial IC analyses of patients with disorders of consciousness.
Soddu, Andrea ULg; Vanhaudenhuyse, Audrey ULg; Bahri, Mohamed Ali ULg et al

in Human Brain Mapping (2011)

Objectives:Recent fMRI studies have shown that it is possible to reliably identify the default-mode network (DMN) in the absence of any task, by resting-state connectivity analyses in healthy volunteers ... [more ▼]

Objectives:Recent fMRI studies have shown that it is possible to reliably identify the default-mode network (DMN) in the absence of any task, by resting-state connectivity analyses in healthy volunteers. We here aimed to identify the DMN in the challenging patient population of disorders of consciousness encountered following coma. Experimental design: A spatial independent component analysis-based methodology permitted DMN assessment, decomposing connectivity in all its different sources either neuronal or artifactual. Three different selection criteria were introduced assessing anticorrelation-corrected connectivity with or without an automatic masking procedure and calculating connectivity scores encompassing both spatial and temporal properties. These three methods were validated on 10 healthy controls and applied to an independent group of 8 healthy controls and 11 severely brain-damaged patients [locked-in syndrome (n = 2), minimally conscious (n = 1), and vegetative state (n = 8)]. Principal observations: All vegetative patients showed fewer connections in the default-mode areas, when compared with controls, contrary to locked-in patients who showed near-normal connectivity. In the minimally conscious-state patient, only the two selection criteria considering both spatial and temporal properties were able to identify an intact right lateralized BOLD connectivity pattern, and metabolic PET data suggested its neuronal origin. Conclusions: When assessing resting-state connectivity in patients with disorders of consciousness, it is important to use a methodology excluding non-neuronal contributions caused by head motion, respiration, and heart rate artifacts encountered in all studied patients. Hum Brain Mapp, 2011. (c) 2011 Wiley-Liss, Inc. [less ▲]

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See detailNeural Correlates of Ongoing Conscious Experience: Both Task-Unrelatedness and Stimulus-Independence Are Related to Default Network Activity
Stawarczyk, David ULg; Majerus, Steve ULg; Maquet, Pierre ULg et al

in PLoS ONE (2011), 6(2), 16997

The default mode network (DMN) is a set of brain regions that consistently shows higher activity at rest compared to tasks requiring sustained focused attention toward externally presented stimuli. The ... [more ▼]

The default mode network (DMN) is a set of brain regions that consistently shows higher activity at rest compared to tasks requiring sustained focused attention toward externally presented stimuli. The cognitive processes that the DMN possibly underlies remain a matter of debate. It has alternately been proposed that DMN activity reflects unfocused attention toward external stimuli or the occurrence of internally generated thoughts. The present study aimed at clarifying this issue by investigating the neural correlates of the various kinds of conscious experiences that can occur during task performance. Four classes of conscious experiences (i.e., being fully focused on the task, distractions by irrelevant sensations/perceptions, interfering thoughts related to the appraisal of the task, and mind-wandering) that varied along two dimensions (“task-relatedness” and “stimulus-dependency”) were sampled using thought-probes while the participants performed a go/no-go task. Analyses performed on the intervals preceding each probe according to the reported subjective experience revealed that both dimensions are relevant to explain activity in several regions of the DMN, namely the medial prefrontal cortex, posterior cingulate cortex/precuneus, and posterior inferior parietal lobe. Notably, an additive effect of the two dimensions was demonstrated for midline DMN regions. On the other hand, lateral temporal regions (also part of the DMN) were specifically related to stimulus-independent reports. These results suggest that midline DMN regions underlie cognitive processes that are active during both internal thoughts and external unfocused attention. They also strengthen the view that the DMN can be fractionated into different subcomponents and reveal the necessity to consider both the stimulus-dependent and the task-related dimensions of conscious experiences when studying the possible functional roles of the DMN. [less ▲]

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See detailfMRI Artefact Rejection and Sleep Scoring Toolbox
Leclercq, Yves ULg; Schrouff, Jessica ULg; Noirhomme, Quentin ULg et al

in Computational Intelligence & Neuroscience (2011)

This paper proposes a toolbox for handling large EEG/ MEG data sets, rejecting the artefact linked to joint fMRI-EEG acquisitions and scoring data sets.

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See detailChanges in functional interactions during anaesthesia-induced loss of consciousness
Schrouff, Jessica ULg; Perlbarg, Vincent; Boly, Mélanie ULg et al

Poster (2010, December 12)

Consciousness has been related to the amount of integrated information that the brain is able to generate. In this paper, we tested the hypothesis that the loss of consciousness caused by propofol ... [more ▼]

Consciousness has been related to the amount of integrated information that the brain is able to generate. In this paper, we tested the hypothesis that the loss of consciousness caused by propofol anesthesia is associated with a significant reduction in the capacity of the brain to integrate information. To assess the functional structure of the whole brain, functional integration and partial correlations were computed from fMRI data acquired from 18 healthy volunteers during resting wakefulness and propofol-induced deep sedation. Total integration was significantly reduced from wakefulness to deep sedation in the whole brain as well as within and between its constituent networks (or systems). Integration was systematically reduced within each system (i.e., brain or networks), as well as between networks. However, the ventral attentional network maintained interactions with most other networks during deep sedation. Partial correlations further suggested that functional connectivity was particularly affected between parietal areas and frontal or temporal regions during deep sedation. Our findings suggest that the breakdown in brain integration is the neural correlate of the loss of consciousness induced by propofol. They stress the important role played by parietal and frontal areas in the generation of consciousness. [less ▲]

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See detailNeural correlates of cognitive control at the item level in the Stroop task.
Grandjean, Julien ULg; D'Ostilio, Kevin ULg; Fias, Wim et al

Poster (2010, November 15)

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See detailInfluence of brain-derived neurotrophic factor val66met human polymorphism on declarative memory consolidation
Mascetti, Laura ULg; Foret, Ariane ULg; Matarazzo, Luca et al

Poster (2010, November 15)

The Brain-Derived Neurotrophic Factor (BDNF) is a neurotrophin which in the adult brain regulates long-term potentiation. In humans, valine (val) to methionine (met) substitution in the 5’ pro-region of ... [more ▼]

The Brain-Derived Neurotrophic Factor (BDNF) is a neurotrophin which in the adult brain regulates long-term potentiation. In humans, valine (val) to methionine (met) substitution in the 5’ pro-region of the BDNF protein is associated with poorer episodic memory. Neurons transfected with met-BDNF-Green Fluorescence Protein showed lower depolarization-induced secretion, while constitutive secretion is unchanged. Here, we hypothesized that the differences in BDNF release determined by this polymorphism would influence memory consolidation and that in comparison with the val/met (=val/met or met/met), val/val individuals would show higher memory performance and different brain responses during a 16h-delayed rather than immediate retrieval session. Participants encoded a series of neutral faces in the afternoon. Retrieval sessions took place one hour after the encoding session, and in the following morning, during the acquisition of functional Magnetic Resonance Imaging (fMRI) time series with a 3 Tesla Allegra scanner. During retrieval, studied faces and new ones were presented in random order. For each stimulus, the subjects indicated whether they could retrieve the encoding episode with (“Remember”), or without details (“Know”), or if they thought the item had not been presented during encoding (“New”). A repeated-measure ANOVA on discrimination index (d’) showed significant effects of group (F(1, 27)=8.65, p=0.007, n(val/val)=14, n(val/met)=15) and session (F(1, 27)=24.64, p=0.000), although the group by session interaction was not significant (F(1, 27)=1.29, p=0.267). fMRI results showed a significant genotype (val/val > val/met) by session (delayed > immediate retrieval) by memory type (Remember > Know) interaction in the right inferior occipital gyrus (x=42, y=-78, z=0, p=0.004, Z=3.77), the left inferior parietal lobule (x=-56, y=-40, z=48, p=0.013, Z=3.43), the posterior cingulate cortex (x=14, y=-42, z=42, p=0.019, Z=3.29) and the right hippocampus (x=28, y=-22, z=-22, p=0.03, Z=3.11). Val/val individuals demonstrate higher memory performance than met-carriers but the change in memory performance between immediate and delayed retests is similar in both allelic groups. In contrast, neural correlates of recollection change between sessions differently according to genotype: responses increase significantly more in val/val than in val/met individuals in brain areas involved in the retrieval, accumulation and binding of perceptual memory details during delayed, relative to immediate retest. These data suggest that activity-dependent BDNF release promotes memory consolidation during the first post-training hours. [less ▲]

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See detailScénario : Notre térritoire a vu disparaître les productions porcine et avicole
Wavreille, José; Boudry, Christelle ULg; Maquet, Pierre ULg

in 10ème journée des Production porcines et avicoles : Nos filières porcines et avicoles : vers plus de durabiltié (2010, October 13)

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See detailInfluence of Brain-Derived Neurotrophic Factor val66met human polymorphism on declarative memory consolidation during sleep
Mascetti, Laura ULg; Foret, Ariane ULg; Matarazzo, Luca et al

Poster (2010, September 15)

Objectives The Brain-Derived Neurotrophic Factor (BDNF) is a neurotrophin which in the adult brain, regulates long-term potentiation and has been involved in the build up of the homeostatic sleep pressure ... [more ▼]

Objectives The Brain-Derived Neurotrophic Factor (BDNF) is a neurotrophin which in the adult brain, regulates long-term potentiation and has been involved in the build up of the homeostatic sleep pressure in rodents. In humans, valine (val) to methionine (met) substitution in the 5’ pro-region of the BDNF protein is associated with poorer episodic memory. Neurons transfected with met-BDNF-Green Fluorescence Protein showed lower depolarization-induced secretion, while constitutive secretion is unchanged. Here, we hypothesized that the differences in BDNF release determined by this polymorphism would influence sleep-dependent memory consolidation and that in comparison with the met-carriers (val/met or met/met), val/val individuals would show higher memory performance after one night of sleep rather than an immediate retrieval session. Methods Participants encoded a series of neutral faces in the afternoon. Retrieval sessions took place one hour after the encoding session, and in the following morning, after a night of polysomnographic-monitored sleep. During retrieval, studied faces and new ones were presented in random order. For each stimulus, the subjects indicated whether they could retrieve the encoding episode with (“Remember” response), or without details (“know” response), or if they thought the item had not been presented during encoding (“New” response). Results A repeated-measure ANOVA on discrimination index (d’) showed significant effects of group (F(1, 22)=4.66, p=0.042) and session (F(1, 22)=12.21, df=1, p=0.002). Although the group by session interaction was not significant (F(1, 22)=1.84, p=0.188), exploratory planned comparisons showed that at immediate retrieval, d’ was not significantly different between groups (val/val, d’ = 1.94±0.16; met-carriers, d’= 1.61±0.14; p>0.5). In contrast, during the second retest (the next day) d’ in the val/val group (d’=2.56±0.23) was significantly higher than in the met-carriers group (d’=1.88±0.21; p=0.041). Likewise, a between-session enhancement in d’ was detected only in the val/val population (p=0.003). Conclusion Val/val individuals demonstrate higher memory performance than met-carriers after a night of sleep but not at immediate retest. These data suggest that activity-dependent BDNF release promotes memory consolidation during the first post-training hours. Further analysis of the present data set will assess the respective effect of sleep and time on the BDNF-associated delayed memory enhancement. This study was supported by FNRS-FRIA, the University of Liège, and the QEMF. [less ▲]

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See detailSleep in Disorders of Consciousness
Schabus, Manuel; Cologan, Victor ULg; Weihart, K et al

Poster (2010, September)

Résultats préliminaires de l'étude du sommeil chez les patients cérébrolésés en état de conscience altéré.

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See detailSleep-dependent consolidation of declarative memories is triggered by hippocampal activation at encoding
Collette, Fabienne ULg; Rauchs, Géraldine; Feyers, Dorothée ULg et al

in Proceedings of Annul Meeting of the Belgian Association for Psychological Sciences (2010, May 28)

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See detailNeural correlates of cognitive control at the item specific level in the Stroop task
Grandjean, Julien ULg; D'Ostilio, Kevin ULg; Fias, Wim et al

Poster (2010, May 04)

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See detailResponse to Comment on “Homeostatic Sleep Pressure and Responses to Sustained Attention in the Suprachiasmatic Area”
Schmidt, Christina ULg; Peigneux, Philippe ULg; Maquet, Pierre ULg et al

in Science (2010)

Astafiev et al. question whether the blood oxygen level–dependent (BOLD) response that we reported in the brainstem was located in the locus coeruleus (LC). Using high-resolution T1-turbo spin echo images ... [more ▼]

Astafiev et al. question whether the blood oxygen level–dependent (BOLD) response that we reported in the brainstem was located in the locus coeruleus (LC). Using high-resolution T1-turbo spin echo images (T1-TSE) acquired in an independent group of subjects, we show that the reported task-related BOLD response in the brainstem is actually compatible with the anatomical location of the LC. [less ▲]

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See detailContribution of sleep to memory consolidation
Shaffii-Le Bourdiec, Anahita; Muto, Vincenzo ULg; Mascetti, Laura et al

in Future Neurology (2010), 5(2), 325-338

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See detailDefault network connectivity reflects the level of consciousness in non-communicative brain-damaged patients.
Vanhaudenhuyse, Audrey ULg; Noirhomme, Quentin ULg; Tshibanda, Luaba ULg et al

in Brain : A Journal of Neurology (2010), 133(Pt 1), 161-71

The 'default network' is defined as a set of areas, encompassing posterior-cingulate/precuneus, anterior cingulate/mesiofrontal cortex and temporo-parietal junctions, that show more activity at rest than ... [more ▼]

The 'default network' is defined as a set of areas, encompassing posterior-cingulate/precuneus, anterior cingulate/mesiofrontal cortex and temporo-parietal junctions, that show more activity at rest than during attention-demanding tasks. Recent studies have shown that it is possible to reliably identify this network in the absence of any task, by resting state functional magnetic resonance imaging connectivity analyses in healthy volunteers. However, the functional significance of these spontaneous brain activity fluctuations remains unclear. The aim of this study was to test if the integrity of this resting-state connectivity pattern in the default network would differ in different pathological alterations of consciousness. Fourteen non-communicative brain-damaged patients and 14 healthy controls participated in the study. Connectivity was investigated using probabilistic independent component analysis, and an automated template-matching component selection approach. Connectivity in all default network areas was found to be negatively correlated with the degree of clinical consciousness impairment, ranging from healthy controls and locked-in syndrome to minimally conscious, vegetative then coma patients. Furthermore, precuneus connectivity was found to be significantly stronger in minimally conscious patients as compared with unconscious patients. Locked-in syndrome patient's default network connectivity was not significantly different from controls. Our results show that default network connectivity is decreased in severely brain-damaged patients, in proportion to their degree of consciousness impairment. Future prospective studies in a larger patient population are needed in order to evaluate the prognostic value of the presented methodology. [less ▲]

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See detailSleep in disorders of consciousness
Cologan, Victor ULg; Schabus, Manuel; LEDOUX, Didier ULg et al

in Sleep Medicine Reviews (2010), 14(2), 97-105

From a behavioral as well as neurobiological point of view, sleep and consciousness are intimately connected. A better understanding of sleep cycles and sleep architecture of patients suffering from ... [more ▼]

From a behavioral as well as neurobiological point of view, sleep and consciousness are intimately connected. A better understanding of sleep cycles and sleep architecture of patients suffering from disorders of consciousness (DOC) might therefore improve the clinical care for these patients as well as our understanding of the neural correlations of consciousness. Defining sleep in severely brain-injured patients is however problematic as both their electrophysiological and sleep patterns differ in many ways from healthy individuals. This paper discusses the concepts involved in the study of sleep of patients suffering from DOC and critically assesses the applicability of standard sleep criteria in these patients. <br /><br />The available literature on comatose and vegetative states as well as that on locked-in and related states following traumatic or non-traumatic severe brain injury will be reviewed. A wide spectrum of sleep disturbances ranging from almost normal patterns to severe loss and architecture disorganization are reported in cases of DOC and some patterns correlate with diagnosis and prognosis. At the present time the interactions of sleep and consciousness in brain-injured patients are a little studied subject but, the authors suggest, a potentially very interesting field of research. [less ▲]

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See detailContributions du sommeil a la consolidation mnésique
Maquet, Pierre ULg; Matarazzo; Foret, Ariane ULg et al

in Biologie Aujourd'hui (2010), 204(2), 139-143

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See detailNeuroimaging of dreaming: state of the art and limitations
Kussé, Caroline ULg; Muto, Vincenzo ULg; Mascetti, Laura ULg et al

in International Review of Neurobiology (2010)

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