References of "Maquet, Pierre"
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See detailPerception of pain in the minimally conscious state with PET activation: an observational study.
Boly, Mélanie ULg; Faymonville, Marie-Elisabeth ULg; Schnakers, Caroline et al

in Lancet Neurology (2008), 7(11), 1013-20

BACKGROUND: Patients in a minimally conscious state (MCS) show restricted self or environment awareness but are unable to communicate consistently and reliably. Therefore, better understanding of cerebral ... [more ▼]

BACKGROUND: Patients in a minimally conscious state (MCS) show restricted self or environment awareness but are unable to communicate consistently and reliably. Therefore, better understanding of cerebral noxious processing in these patients is of clinical, therapeutic, and ethical relevance. METHODS: We studied brain activation induced by bilateral electrical stimulation of the median nerve in five patients in MCS (aged 18-74 years) compared with 15 controls (19-64 years) and 15 patients (19-75 years) in a persistent vegetative state (PVS) with (15)O-radiolabelled water PET. By way of psychophysiological interaction analysis, we also investigated the functional connectivity of the primary somatosensory cortex (S1) in patients and controls. Patients in MCS were scanned 57 (SD 33) days after admission, and patients in PVS 36 (9) days after admission. Stimulation intensities were 8.6 (SD 6.7) mA in patients in MCS, 7.4 (5.9) mA in controls, and 14.2 (8.7) mA in patients in PVS. Significant results were thresholded at p values of less than 0.05 and corrected for multiple comparisons. FINDINGS: In patients in MCS and in controls, noxious stimulation activated the thalamus, S1, and the secondary somatosensory or insular, frontoparietal, and anterior cingulate cortices (known as the pain matrix). No area was less activated in the patients in MCS than in the controls. All areas of the cortical pain matrix showed greater activation in patients in MCS than in those in PVS. Finally, in contrast with patients in PVS, those in MCS had preserved functional connectivity between S1 and a widespread cortical network that includes the frontoparietal associative cortices. INTERPRETATION: Cerebral correlates of pain processing are found in a similar network in controls and patients in MCS but are much more widespread than in patients in PVS. These findings might be objective evidence of a potential pain perception capacity in patients in MCS, which supports the idea that these patients need analgesic treatment. [less ▲]

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See detailChronotype-dependent performance modulation according to time of day : a functional neuroimaging approach
Schmidt, Christina; Collette, Fabienne ULg; Sterpenich, Virginie et al

in NeuroImage (2008), 41(Suppl. 1),

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See detailOwl or lark? Stroop-related cerebral activity is modulated by time of day and chronotype
Schmidt, Christina; Collette, Fabienne ULg; Sterpenich, Virginie et al

in Journal of Sleep Research (2008), 17(Suppl. 1),

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See detailPolymorphism in PERIOD3 predicts fMRI-assessed inter-individual differences in the effects of sleep deprivation
Vandewalle, Gilles ULg; Archer, Simon; Wuillaume, Catherine et al

in Journal of Sleep Research (2008), 17(Suppl. 1),

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See detailA PERIOD3 polymorphism predicts fMRI assessed brain responses following sleep loss
Vandewalle, Gilles ULg; Archer, Simon; Wuillaume, Catherine et al

in Sleep (2008), 31(Suppl. 1),

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See detailConsciousness and cerebral baseline activity fluctuations
Boly, Mélanie ULg; Phillips, Christophe ULg; Balteau, Evelyne ULg et al

in Human Brain Mapping (2008), 29

The origin of within-subject variability in perceptual experiments is poorly understood. We here review evidence that baseline brain activity in the areas involved in sensory perception predict subsequent ... [more ▼]

The origin of within-subject variability in perceptual experiments is poorly understood. We here review evidence that baseline brain activity in the areas involved in sensory perception predict subsequent variations in sensory awareness. We place these findings in light of recent findings on the architecture of spontaneous BOLD fluctuations in the awake human brain, and discuss the possible origins of the observed baseline brain activity fluctuations. [less ▲]

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See detailIs there anybody in there? Detecting awareness in disorders of consciousness.
Demertzi, Athena; Vanhaudenhuyse, Audrey ULg; Bruno, Marie-Aurelie et al

in Expert Review of Neurotherapeutics (2008), 8(11), 1719-30

The bedside detection of awareness in disorders of consciousness (DOC) caused by acquired brain injury is not an easy task. For this reason, differential diagnosis using neuroimaging and ... [more ▼]

The bedside detection of awareness in disorders of consciousness (DOC) caused by acquired brain injury is not an easy task. For this reason, differential diagnosis using neuroimaging and electrophysiological tools in search for objective markers of consciousness is being employed. However, such tools cannot be considered as diagnostic per se, but as assistants to the clinical evaluation, which, at present, remains the gold standard. Regarding therapeutic management in DOC, no evidence-based recommendations can be made in favor of a specific treatment. The present review summarizes clinical and paraclinical studies that have been conducted with neuroimaging and electrophysiological techniques in search of residual awareness in DOC. We discuss the medical, scientific and ethical implications that derive from these studies and we argue that, in the future, the role of neuroimaging and electrophysiology will be important not only for the diagnosis and prognosis of DOC but also in establishing communication with these challenging patients. [less ▲]

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See detailRevelations from the unconscious: studying residual brain function in coma and related states.
Laureys, Steven ULg; Boly, Mélanie ULg; Schnakers, Caroline ULg et al

in Bulletin et Mémoires de l'Académie Royale de Médecine de Belgique (2008), 163(7-9), 381-8388-90

The purpose of our research is to contribute to a better understanding of the residual brain function of patients who survive an acute brain damage but remain in a coma, vegetative state, minimally ... [more ▼]

The purpose of our research is to contribute to a better understanding of the residual brain function of patients who survive an acute brain damage but remain in a coma, vegetative state, minimally conscious state or locked-in syndrome. The diagnosis, prognosis, therapy and medical management of these patients remain difficult. These studies are also of interest scientifically, as they help to elucidate the neural correlates of human consciousness. We here review our studies on bedside behavioral evaluation scales, electrophysiology and functional neuroimaging in these disorders of consciousness and conclude by discussing methodological and ethical issues and current concepts of the standards for care and quality of life in these challenging conditions. [less ▲]

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See detailImagerie cérébrale de la réflexion sur soi
Salmon, Eric ULg; D'Argembeau, Arnaud ULg; Bastin, Christine ULg et al

in Revue Médicale de Liège (2008), 63

Precise brain regions are activated when a subject gives a judgment on himself. Those are the medial parietal cortex, essentially related to episodic memory processing, and the ventromedial prefrontal ... [more ▼]

Precise brain regions are activated when a subject gives a judgment on himself. Those are the medial parietal cortex, essentially related to episodic memory processing, and the ventromedial prefrontal cortex, recruited for evaluating the personal valence of an information. These regions are not activated in Alzheimer's disease. The decrease of awareness for own deficits in a patient with Alzheimer's disease would depend on a reduction of episodic memory capacities and a worsening of judgment for self significance. [less ▲]

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See detailHypnose et perception de la douleur
Vanhaudenhuyse, Audrey ULg; Boveroux, Pierre ULg; Boly, Mélanie ULg et al

in Revue Médicale de Liège (2008), 63(5-6), 424-8

Improvement in functional neuroimaging allows researchers to disentangle the brain mechanisms involved in the pain modulation encountered during hypnosis. It has been shown that the anterior cingulate and ... [more ▼]

Improvement in functional neuroimaging allows researchers to disentangle the brain mechanisms involved in the pain modulation encountered during hypnosis. It has been shown that the anterior cingulate and prefrontal cortices are important in the modulation of incoming sensory and noxious input. Moreover, clinical studies in certain types of surgery (eg thyroidectomy, mastectomy and plastic surgery) have demonstrated that hypnosis may avoid general anesthesia. [less ▲]

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See detailBoth the hippocampus and striatum are involved in consolidation of motor sequence memory.
Albouy, Geneviève ULg; Sterpenich, Virginie ULg; Balteau, Evelyne ULg et al

in Neuron (2008), 58(2), 261-72

Functional magnetic resonance imaging (fMRI) was used to investigate the cerebral correlates of motor sequence memory consolidation. Participants were scanned while training on an implicit oculomotor ... [more ▼]

Functional magnetic resonance imaging (fMRI) was used to investigate the cerebral correlates of motor sequence memory consolidation. Participants were scanned while training on an implicit oculomotor sequence learning task and during a single testing session taking place 30 min, 5 hr, or 24 hr later. During training, responses observed in hippocampus and striatum were linearly related to the gain in performance observed overnight, but not over the day. Responses in both structures were significantly larger at 24 hr than at 30 min or 5 hr. Additionally, the competitive interaction observed between these structures during training became cooperative overnight. These results stress the importance of both hippocampus and striatum in procedural memory consolidation. Responses in these areas during training seem to condition the overnight memory processing that is associated with a change in their functional interactions. These results show that both structures interact during motor sequence consolidation to optimize subsequent behavior. [less ▲]

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See detailNeuroimaging insights into the pathophysiology of sleep disorders.
Desseilles, Martin ULg; Dang Vu, Thien Thanh ULg; Schabus, Manuel et al

in Sleep (2008), 31(6), 777-94

Neuroimaging methods can be used to investigate whether sleep disorders are associated with specific changes in brain structure or regional activity. However, it is still unclear how these new data might ... [more ▼]

Neuroimaging methods can be used to investigate whether sleep disorders are associated with specific changes in brain structure or regional activity. However, it is still unclear how these new data might improve our understanding of the pathophysiology underlying adult sleep disorders. Here we review functional brain imaging findings in major intrinsic sleep disorders (i.e., idiopathic insomnia, narcolepsy, and obstructive sleep apnea) and in abnormal motor behavior during sleep (i.e., periodic limb movement disorder and REM sleep behavior disorder). The studies reviewed include neuroanatomical assessments (voxel-based morphometry, magnetic resonance spectroscopy), metabolic/functional investigations (positron emission tomography, single photon emission computed tomography, functional magnetic resonance imaging), and ligand marker measurements. Based on the current state of the research, we suggest that brain imaging is a useful approach to assess the structural and functional correlates of sleep impairments as well as better understand the cerebral consequences of various therapeutic approaches. Modem neuroimaging techniques therefore provide a valuable tool to gain insight into possible pathophysiological mechanisms of sleep disorders in adult humans. [less ▲]

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See detailSpontaneous neural activity during human slow wave sleep.
Dang Vu, Thien Thanh ULg; Schabus, Manuel ULg; Desseilles, Martin ULg et al

in Proceedings of the National Academy of Sciences of the United States of America (2008), 105(39), 15160-5

Slow wave sleep (SWS) is associated with spontaneous brain oscillations that are thought to participate in sleep homeostasis and to support the processing of information related to the experiences of the ... [more ▼]

Slow wave sleep (SWS) is associated with spontaneous brain oscillations that are thought to participate in sleep homeostasis and to support the processing of information related to the experiences of the previous awake period. At the cellular level, during SWS, a slow oscillation (<1 Hz) synchronizes firing patterns in large neuronal populations and is reflected on electroencephalography (EEG) recordings as large-amplitude, low-frequency waves. By using simultaneous EEG and event-related functional magnetic resonance imaging (fMRI), we characterized the transient changes in brain activity consistently associated with slow waves (>140 microV) and delta waves (75-140 microV) during SWS in 14 non-sleep-deprived normal human volunteers. Significant increases in activity were associated with these waves in several cortical areas, including the inferior frontal, medial prefrontal, precuneus, and posterior cingulate areas. Compared with baseline activity, slow waves are associated with significant activity in the parahippocampal gyrus, cerebellum, and brainstem, whereas delta waves are related to frontal responses. No decrease in activity was observed. This study demonstrates that SWS is not a state of brain quiescence, but rather is an active state during which brain activity is consistently synchronized to the slow oscillation in specific cerebral regions. The partial overlap between the response pattern related to SWS waves and the waking default mode network is consistent with the fascinating hypothesis that brain responses synchronized by the slow oscillation restore microwake-like activity patterns that facilitate neuronal interactions. [less ▲]

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See detailQue mesure la neuro-imagerie fonctionnelle: IRMf, TEP & MEG?
Gosseries, Olivia ULg; Demertzi, Athina ULg; Noirhomme, Quentin ULg et al

in Revue Médicale de Liège (2008), 63(5-6), 231-7

Functional cerebral imaging techniques allow the in vivo study of human cognitive and sensorimotor functions in physiological or pathological conditions. In this paper, we review the advantages and ... [more ▼]

Functional cerebral imaging techniques allow the in vivo study of human cognitive and sensorimotor functions in physiological or pathological conditions. In this paper, we review the advantages and limitations of functional magnetic resonance imaging (fMRI), positron emission tomography (PET) and magnetoencephalography (MEG). fMRI and PET measure haemodynamic changes induced by regional changes in neuronal activity. These techniques have a high spatial resolution (a few millimeters), but a poor temporal resolution (a few seconds to several minutes). Electroencephalogram (EEG) and MEG measure the neuronal electrical or magnetic activity with a high temporal resolution (i.e., milliseconds) albeit with a poorer spatial resolution (i.e., a few millimeters to one centimeter). The combination of these different neuroimaging techniques allows studying different components of the brain's activity (e.g., neurovascular coupling, electromagnetic activity) with both a high temporal and spatial resolution. [less ▲]

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See detailProteomic changes in rat hippocampus and adrenals following short-term sleep deprivation.
Poirrier, Jean-Etienne; Guillonneau, Francois; Renaut, Jenny et al

in Proteome Science (2008), 6

ABSTRACT: BACKGROUND: To identify the biochemical changes induced by sleep deprivation at a proteomic level, we compared the hippocampal proteome of rats either after 4 hours of sleep or sleep deprivation ... [more ▼]

ABSTRACT: BACKGROUND: To identify the biochemical changes induced by sleep deprivation at a proteomic level, we compared the hippocampal proteome of rats either after 4 hours of sleep or sleep deprivation obtained by gentle handling. Because sleep deprivation might induce some stress, we also analyzed proteomic changes in rat adrenals in the same conditions. After sleep deprivation, proteins from both tissues were extracted and subjected to 2D-DIGE analysis followed by protein identification through mass spectrometry and database search. RESULTS: In the hippocampus, 87 spots showed significant variation between sleep and sleep deprivation, with more proteins showing higher abundance in the latter case. Of these, 16 proteins were present in sufficient amount for a sequencing attempt and among the 12 identified proteins, inferred affected cellular functions include cell metabolism, energy pathways, transport and vesicle trafficking, cytoskeleton and protein processing. Although we did not observe classical, macroscopic effect of stress in sleep-deprived rats, 47 protein spots showed significant variation in adrenal tissue between sleep and sleep deprivation, with more proteins showing higher abundance following sleep. Of these, 16 proteins were also present in sufficient amount for a sequencing attempt and among the 13 identified proteins, the most relevant cellular function that was affected was cell metabolism. CONCLUSION: At a proteomic level, short term sleep deprivation is characterized by a higher expression of some proteins in the hippocampus and a lower abundance of other proteins in the adrenals (compared to normal sleep control). Altogether, this could indicate a general activation of a number of cellular mechanisms involved in the maintenance of wakefulness and in increased energy expenditure during sleep deprivation. These findings are relevant to suggested functions of sleep like energy repletion and the restoration of molecular stocks or a more global homeostasis of synaptic processes. [less ▲]

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See detailNeural networks for short-term memory for order differentiate high and low proficiency bilinguals
Majerus, Steve ULg; Belayachi, Sanaa ULg; De Smedt, Bert et al

in NeuroImage (2008), 42

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See detailSelf-reflection across time: cortical midline structures differentiate between present and past selves
D'Argembeau, Arnaud ULg; Feyers, Dorothée ULg; Majerus, Steve ULg et al

in Social Cognitive and Affective Neuroscience (2008), 3(3), 244-252

The processing of personal changes across time and the ability to differentiate between representations of present and past selves are crucial for developing a mature sense of identity. In this study, we ... [more ▼]

The processing of personal changes across time and the ability to differentiate between representations of present and past selves are crucial for developing a mature sense of identity. In this study, we explored the neural correlates of self-reflection across time using functional magnetic resonance imaging (fMRI). College undergraduates were asked to reflect on their own psychological characteristics and those of an intimate other, for both the present time period (i.e. at college) and a past time period (i.e. high school years) that involved significant personal changes. Cortical midline structures (CMS) were commonly recruited by the four reflective tasks (reflecting on the present self, past self, present other and past other), relative to a control condition (making valence judgments). More importantly, however, the degree of activity in CMS also varied significantly according to the target of reflection, with the ventral and dorsal medial prefrontal cortex and the posterior cingulate cortex being more recruited when reflecting on the present self than when reflecting on the past self or when reflecting on the other person. These findings suggest that CMS may contribute to differentiate between representations of present and past selves. [less ▲]

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See detailBrain function in physiologically, pharmacologically, and pathologically altered states of consciousness
Boveroux, Pierre ULg; Bonhomme, Vincent ULg; Vanhaudenhuyse, Audrey ULg et al

in International Anesthesiology Clinics (2008), 46(3), 131-146

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See detailOffline processing of memories induced by perceptual visual learning during subsequent wakefulness and sleep: A behavioral study.
Matarazzo, Luca ULg; Franko, Edit; Maquet, Pierre ULg et al

in Journal of Vision (2008), 8(4), 71-9

To further characterize perceptual memory consolidation during sleep, we used a coarse orientation discrimination task in which participants had to discriminate the orientation of orthogonal gratings ... [more ▼]

To further characterize perceptual memory consolidation during sleep, we used a coarse orientation discrimination task in which participants had to discriminate the orientation of orthogonal gratings occluded by increasing levels of noise. In a first study (N = 11), we showed that the learning effect in this task is retinotopic (position-specific) and orientation specific. In a second experiment, we assessed the effect of nocturnal sleep, as opposed to the effect of time, on perceptual learning. A first group of participants was trained in the morning, tested in the evening and retested the next morning (morning-evening-morning, MEM, N = 11); a second group was trained in the evening, tested the next morning, and retested in the evening (evening-morning-evening; EME; N = 12). Between training and testing, EME subjects improved significantly more (after a night of sleep) than MEM subjects (after 12 waking hours). Similarly, between test and retest, performance of MEM subjects (after a full night of sleep) improved significantly more than in EME subjects (after 12 further waking hours). These results suggest a beneficial effect of sleep on coarse orientation discrimination. Further studies are needed to characterize the neural correlates of this perceptual learning and the offline consolidation of perceptual memory. [less ▲]

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