Modulation of fMRI assessed brain responses to blue and green light by sleep homeostasis, circadian phase and PER3 polymorphism
Vandewalle, Gilles ; ; et al
in Sleep (2009), 32(Suppl. 1),Detailed reference viewed: 30 (2 ULg)
Pain and non-pain processing during hypnosis: a thulium-YAG event-related fMRI study.
Vanhaudenhuyse, Audrey ; Boly, Mélanie ; Balteau, Evelyne et al
in NeuroImage (2009), 47(3), 1047-54
The neural mechanisms underlying the antinociceptive effects of hypnosis still remain unclear. Using a parametric single-trial thulium-YAG laser fMRI paradigm, we assessed changes in brain activation and ... [more ▼]
The neural mechanisms underlying the antinociceptive effects of hypnosis still remain unclear. Using a parametric single-trial thulium-YAG laser fMRI paradigm, we assessed changes in brain activation and connectivity related to the hypnotic state as compared to normal wakefulness in 13 healthy volunteers. Behaviorally, a difference in subjective ratings was found between normal wakefulness and hypnotic state for both non-painful and painful intensity-matched stimuli applied to the left hand. In normal wakefulness, non-painful range stimuli activated brainstem, contralateral primary somatosensory (S1) and bilateral insular cortices. Painful stimuli activated additional areas encompassing thalamus, bilateral striatum, anterior cingulate (ACC), premotor and dorsolateral prefrontal cortices. In hypnosis, intensity-matched stimuli in both the non-painful and painful range failed to elicit any cerebral activation. The interaction analysis identified that contralateral thalamus, bilateral striatum and ACC activated more in normal wakefulness compared to hypnosis during painful versus non-painful stimulation. Finally, we demonstrated hypnosis-related increases in functional connectivity between S1 and distant anterior insular and prefrontal cortices, possibly reflecting top-down modulation. [less ▲]Detailed reference viewed: 147 (30 ULg)
Hypnosis and cingulate-mediated mechanisms of analgesia
FAYMONVILLE, Marie-Elisabeth ; ; Maquet, Pierre et al
in Vogt, Brent (Ed.) Cingulate Neurobiology and Disease (2009)Detailed reference viewed: 46 (5 ULg)
Some facts about sleep relevant for Landau-Kleffner syndrome.
Mascetti, Laura ; Foret, Ariane ; et al
in Epilepsia (2009), 50 Suppl 7
Our understanding of the neural mechanisms of non-rapid eye movement sleep (NREM) is steadily increasing. Given the intriguing activation of paroxysmal activity during NREM sleep in patients with Landau ... [more ▼]
Our understanding of the neural mechanisms of non-rapid eye movement sleep (NREM) is steadily increasing. Given the intriguing activation of paroxysmal activity during NREM sleep in patients with Landau-Kleffner syndrome (LKS), a thorough characterization of commonalities and differences between the neural correlates of LKS paroxysms and normal sleep oscillations might provide useful information on the neural underpinning of this disorder. Especially, given the suspected role of sleep in brain plasticity, this type of information is needed to assess the link between cognitive deterioration and electroencephalography (EEG) paroxysms during sleep. [less ▲]Detailed reference viewed: 37 (3 ULg)
Rejection of pulse related artefact (PRA) from continuous electroencephalographic (EEG) time series recorded during functional magnetic resonance imaging (fMRI) using constraint independent component analysis (cICA).
Leclercq, Yves ; Balteau, Evelyne ; Dang Vu, Thien Thanh et al
in NeuroImage (2009), 44(3), 679-91
Rejection of the pulse related artefact (PRA) from electroencephalographic (EEG) time series recorded simultaneously with fMRI data is difficult, particularly during NREM sleep because of the similarities ... [more ▼]
Rejection of the pulse related artefact (PRA) from electroencephalographic (EEG) time series recorded simultaneously with fMRI data is difficult, particularly during NREM sleep because of the similarities between sleep slow waves and PRA, in both temporal and frequency domains and the need to work with non-averaged data. Here we introduce an algorithm based on constrained independent component analysis (cICA) for PRA removal. This method has several advantages: (1) automatic detection of the components corresponding to the PRA; (2) stability of the solution and (3) computational treatability. Using multichannel EEG recordings obtained in a 3 T MR scanner, with and without concomitant fMRI acquisition, we provide evidence for the sensitivity and specificity of the method in rejecting PRA in various sleep and waking conditions. [less ▲]Detailed reference viewed: 28 (5 ULg)
Sleep : Implications for Theories of Dreaming and Consciousness
Dang Vu, Thien Thanh ; ; et al
in Banks, William (Ed.) Encyclopaedia of Consciousness (2009)Detailed reference viewed: 102 (0 ULg)
Light as a modulator of cognitive brain function
Vandewalle, Gilles ; Maquet, Pierre ;
in Trends in Cognitive Sciences (2009), 13(10), 429-38
Humans are a diurnal species usually exposed to light while engaged in cognitive tasks. Light not only guides performance on these tasks through vision but also exerts non-visual effects that are mediated ... [more ▼]
Humans are a diurnal species usually exposed to light while engaged in cognitive tasks. Light not only guides performance on these tasks through vision but also exerts non-visual effects that are mediated in part by recently discovered retinal ganglion cells maximally sensitive to blue light. We review recent neuroimaging studies which demonstrate that the wavelength, duration and intensity of light exposure modulate brain responses to (non-visual) cognitive tasks. These responses to light are initially observed in alertness-related subcortical structures (hypothalamus, brainstem, thalamus) and limbic areas (amygdala and hippocampus), followed by modulations of activity in cortical areas, which can ultimately affect behaviour. Light emerges as an important modulator of brain function and cognition. [less ▲]Detailed reference viewed: 45 (3 ULg)
Functional connectivity in the default network during resting state is preserved in a vegetative but not in a brain dead patient.
Boly, Mélanie ; Tshibanda, Luaba ; Vanhaudenhuyse, Audrey et al
in Human Brain Mapping (2009), 30(8), 2393-400
Recent studies on spontaneous fluctuations in the functional MRI blood oxygen level-dependent (BOLD) signal in awake healthy subjects showed the presence of coherent fluctuations among functionally ... [more ▼]
Recent studies on spontaneous fluctuations in the functional MRI blood oxygen level-dependent (BOLD) signal in awake healthy subjects showed the presence of coherent fluctuations among functionally defined neuroanatomical networks. However, the functional significance of these spontaneous BOLD fluctuations remains poorly understood. By means of 3 T functional MRI, we demonstrate absent cortico-thalamic BOLD functional connectivity (i.e. between posterior cingulate/precuneal cortex and medial thalamus), but preserved cortico-cortical connectivity within the default network in a case of vegetative state (VS) studied 2.5 years following cardio-respiratory arrest, as documented by extensive behavioral and paraclinical assessments. In the VS patient, as in age-matched controls, anticorrelations could also be observed between posterior cingulate/precuneus and a previously identified task-positive cortical network. Both correlations and anticorrelations were significantly reduced in VS as compared to controls. A similar approach in a brain dead patient did not show any such long-distance functional connectivity. We conclude that some slow coherent BOLD fluctuations previously identified in healthy awake human brain can be found in alive but unaware patients, and are thus unlikely to be uniquely due to ongoing modifications of conscious thoughts. Future studies are needed to give a full characterization of default network connectivity in the VS patients population. [less ▲]Detailed reference viewed: 85 (20 ULg)
Homeostatic sleep pressure and responses to sustained attention in the suprachiasmatic area.
Schmidt, Christina ; Collette, Fabienne ; Leclercq, Yves et al
in Science (2009), 324(5926), 516-9
Throughout the day, cognitive performance is under the combined influence of circadian processes and homeostatic sleep pressure. Some people perform best in the morning, whereas others are more alert in ... [more ▼]
Throughout the day, cognitive performance is under the combined influence of circadian processes and homeostatic sleep pressure. Some people perform best in the morning, whereas others are more alert in the evening. These chronotypes provide a unique way to study the effects of sleep-wake regulation on the cerebral mechanisms supporting cognition. Using functional magnetic resonance imaging in extreme chronotypes, we found that maintaining attention in the evening was associated with higher activity in evening than morning chronotypes in a region of the locus coeruleus and in a suprachiasmatic area (SCA) including the circadian master clock. Activity in the SCA decreased with increasing homeostatic sleep pressure. This result shows the direct influence of the homeostatic and circadian interaction on the neural activity underpinning human behavior. [less ▲]Detailed reference viewed: 131 (22 ULg)
Perspective taking to assess self-personality: What's modified in Alzheimer's disease?
; Collette, Fabienne ; D'Argembeau, Arnaud et al
in Neurobiology of Aging (2009), 30(10), 1637-1651
Personality changes are frequently described by caregivers of patients with Alzheimer's disease, while they are less often reported by the patients. This relative anosognosia of Alzheimer disease (AD ... [more ▼]
Personality changes are frequently described by caregivers of patients with Alzheimer's disease, while they are less often reported by the patients. This relative anosognosia of Alzheimer disease (AD) patients for personality changes might be related to impaired self-judgment and to decreased ability to understand their caregiver's perspective. To investigate this issue, we explored the cerebral correlates of self-assessment and perspective taking in patients with mild AD, elderly and young volunteers. All subjects assessed relevance of personality traits adjectives for self and a relative, taking either their own or their relative's perspective, during a functional imaging experiment. The comparison of subject's and relative's answers provided congruency scores used to assess self-judgment and perspective taking performance. The self-judgment "accuracy" score was diminished in AD, and when patients assessed adjectives for self-relevance, they predominantly activated bilateral intraparietal sulci (IPS). Previous studies associated IPS activation with familiarity judgment, which AD patients would use more than recollection when retrieving information to assess self-personality. When taking a third-person perspective, patients activated prefrontal regions (similarly to young volunteers), while elderly controls recruited visual associative areas (also activated by young volunteers). This suggests that mild AD patients relied more on reasoning processes than on visual imagery of autobiographical memories to take their relative's perspective. This strategy may help AD patients to cope with episodic memory impairment even if it does not prevent them from making some mind-reading errors. [less ▲]Detailed reference viewed: 71 (10 ULg)
Bispectral index correlates with regional cerebral blood flow during sleep in distinct cortical and subcortical structures in humans.
Noirhomme, Quentin ; Boly, Mélanie ; Bonhomme, Vincent et al
in Archives Italiennes de Biologie (2009), 147(1-2), 51-7
The relationship between the Bispectral Index (BIS), an EEG-based monitor of anesthesia, and brain activity is still unclear. This study aimed at investigating the relationship between changes in BIS ... [more ▼]
The relationship between the Bispectral Index (BIS), an EEG-based monitor of anesthesia, and brain activity is still unclear. This study aimed at investigating the relationship between changes in BIS values during natural sleep and regional cerebral blood flow (rCBF) variations, as measured by Positron Emission Tomography (PET). Data were obtained from six young, healthy, right-handed, male volunteers (20-30 years old) using the H2(15)O infusion method. PET scans were performed both during waking and various stages of sleep. BIS values were monitored continuously and recorded during each PET scan. Positive correlations were detected between BIS and rCBF values in dorsolateral prefontal, parietal, anterior and posterior cingulate, precuneal, mesiofrontal, mesiotemporal and insular cortices. These areas belong to a frontoparietal network known to be related to awareness of self conscious sensory perception, attention and memory. BIS values also positively correlated with activity in brainstem and thalami, both structures known to be involved in arousal and wakefulness. These results show that BIS changes associated with physiological sleep depth co-vary with the activity of specific cortical and subcortical areas. The latter are known to modulate arousal, which in turn allows sustained thalamo-cortical enhancement of activity in a specific frontoparietal network known to be related to the content of consciousness. Thus, although mainly derived from frontal EEG, BIS could represent a wider index of cerebral activity. [less ▲]Detailed reference viewed: 95 (7 ULg)
Neuroimaging of narcolepsy
Dang Vu, Thien Thanh ; Desseilles, Martin ; et al
in CNS & Neurological Disorders Drug Targets (2009), 8(4), 254-263
Neuroimaging techniques have refined the characterization of neural structures involved in the regulation of normal sleep-wake cycle in healthy humans. Yet brain imaging studies in patients with sleep ... [more ▼]
Neuroimaging techniques have refined the characterization of neural structures involved in the regulation of normal sleep-wake cycle in healthy humans. Yet brain imaging studies in patients with sleep disorders still remain scarce. In narcoleptic patients, structural and functional brain imaging studies have suggested the involvement of the hypothalamus in the pathophysiology of narcolepsy, plausibly consistent with an impairment of the hypocretin-orexin system. Some recent studies have further suggested that cataplexy, a key feature of the narcoleptic syndrome, might result from a dysfunction of the hypothalamus and its interactions with limbic structures. Other neuroimaging studies have focused on the assessment of neurotransmission and the effects of pharmacological treatment in narcoleptic patients. However, the neural correlates of some main symptoms of narcolepsy, such as sleep attacks, hypnagogic/hypnopompic hallucinations and sleep paralysis, are still unknown. In addition, the description of brain activity patterns during sleep in narcoleptic patients needs further investigation. Neuroimaging has proven to be a valuable tool for the study of sleep regulation and sleep disorders; its future developments will undoubtedly improve our understanding of the neural mechanisms underlying narcolepsy with cataplexy. [less ▲]Detailed reference viewed: 50 (20 ULg)
Repetitive transcranial magnetic stimulation over the primary motor cortex disrupts early boost but not delayed gains in performance in motor sequence learning
; Peigneux, Philippe ; MAERTENS DE NOORDHOUT, Alain et al
in European Journal of Neuroscience (2008), 28(6), 1216-1221Detailed reference viewed: 17 (0 ULg)
Abnormal neural filtering of irrelevant information in depressed patients Abstract Book of the conference
Desseilles, Martin ; Balteau, Evelyne ; et al
Conference (2008, July 11)Detailed reference viewed: 5 (0 ULg)
A PERIOD3 polymorphism predicts fMRI assessed brain responses following sleep loss
Vandewalle, Gilles ; ; et al
Conference (2008, June)Detailed reference viewed: 11 (1 ULg)
The importance of serial order short-term memory for lexical bilingual proficiency: Evidence from functional neiroimaging.
Majerus, Steve ; Belayachi, Sanaa ; et al
Conference (2008, May 26)Detailed reference viewed: 14 (0 ULg)